AeroElectric-Archive.digest.vol-kb
January 22, 2011 - February 05, 2011
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________________________________________________________________________________
| From: | "Robert L. Nuckolls, III" <nuckolls.bob(at)aeroelectric.com> |
At 06:08 PM 1/22/2011, you wrote:
>
>
>In the late 60's I was working for Kaiser Aluminum when one of their
>engineers successfully bonded copper bar to aluminum bar stock. This
>was a great cost saver in the aluminum manufacturing plants when
>sending the high voltage from the power plant to the furnace.
>
>I didn't work in that area and I don't know how successful it was in practice.
actually, there's a class of copper clad aluminum
wire used to make up large bundles of high current
conductors. Eric Jones offers some light-weight
alternatives to the 2 and 4 awg all copper choices.
http://www.periheliondesign.com/fatwires.htm
I've played with this stuff and for all practical
purposes it solders and crimps like copper wire
but without the dissimilar metal issues. The
wire is also much finer strands than those wires
used in early attempts to "aluminize" the fat
wires in airplanes. This makes the wire much
more flexible and resistant to stress cranking
under flexure.
I think Hawker Beech is using some copper clad
aluminum on the production line. So yes, I believe
bus bars made primarily of aluminum with copper
connecting surfaces fused to the aluminum would
have been quite practical.
Bob . . .
________________________________________________________________________________
| Subject: | Off topic electric drag racer |
| From: | Robert Mitchell <rmitch1(at)hughes.net> |
So, what are the Batteries here?
Bob Mitchell
L-320
>
>
>
> If a little guy in a home garage can make this, what are all the big car
makers doing in all their giant labs?
> www.opb.org/programs/ofg/videos/view/56-Electric-Drag-Racing
>
________________________________________________________________________________
| From: | "Ralph & Maria Finch" <ralphmariafinch(at)gmail.com> |
| Subject: | Here's a chance to own the best . . . |
FYI, 3 years ago I bought this model of crimper on eBay for $68 including
shipping. Great tool.
Ralph Finch
Davis, California, USA
RV-9A QB-SA
From: owner-aeroelectric-list-server(at)matronics.com
[mailto:owner-aeroelectric-list-server(at)matronics.com] On Behalf Of Robert L.
Nuckolls, III
Sent: Saturday, January 22, 2011 1:23 PM
Subject: AeroElectric-List: Here's a chance to own the best . . .
While looking for other things on eBay I ran across this
listing
http://tinyurl.com/4d8nu7r
It's for the Tyco-Amp 59170 t-head, red/blue crimp
tool. All of my tools are 59250 but when you check
the data sheet . . .
http://aeroelectric.com/Mfgr_Data/Tools/Tyco-AMP/59250.pdf
it appears that everything the 59250 does, the 59170 does
also. In fact, it wasn't clear to me what, if any, differences
there were between the two model numbers. These tools now retail
new for over $1000. Check out the data sheet for yourself but
if you've a hankering to own the best, this is one to consider.
Bob . . .
________________________________________________________________________________
| From: | "Robert L. Nuckolls, III" <nuckolls.bob(at)aeroelectric.com> |
| Subject: | Re: Off topic electric drag racer |
At 10:20 PM 1/22/2011, you wrote:
>So, what are the Batteries here?
He started the video with and Exide product and
judging from the weight difference for the "new"
batteries, they were probably lead-acid. The
last runs were with A123 Systems Li-ion batteries.
Some of you may recall Bill Dube used to post
here on the List several years ago. His KillaCycle
has put in come amazing performance numbers.
He did experience a "bad day in the cockpit"
during some street exhibition of the bike
back in Sept of 2007
http://green.autoblog.com/2007/09/14/killacycle-takes-off-crashes-into-parked-minivan-bill-dube-ok/
HBC had looked at A123 products as potential
feedstock for a new aircraft battery but it
never took off for variety of reasons. There
IS a specification in work (it may be released
by now) for qualifying Li-ion batteries for
aircraft.
I'm sure you're all aware of the potential energy
release from a faulted SVLA battery . . . the
Li-Ions are a whole 'nuther step up. It's sorta
like figuring out how to safely burn nitroglycerin
in your engine . . . the BTU to volume ratio
is really good . . . but . . .
I have no doubt they are coming . . . but not
real soon.
Bob . . .
________________________________________________________________________________
| From: | Dave Saylor <dave.saylor.aircrafters(at)gmail.com> |
| Subject: | Re: Off topic electric drag racer |
Bill Dube (riding the Killacyle) was providing LED nav lights for
experimentals at one point. I bought a set from him. He's a great guy.
Dave Saylor
AirCrafters
140 Aviation Way
Watsonville, CA 95076
831-722-9141 Shop
831-750-0284 Cell
On Sat, Jan 22, 2011 at 7:20 PM, Robert Mitchell wrote:
> So, what are the Batteries here?
>
> Bob Mitchell
> L-320
>
>
> If a little guy in a home garage can make this, what are all the big car
> makers doing in all their giant labs?
> <http://www.opb.org/programs/ofg/videos/view/56-Electric-Drag-Racing>
> www.opb.org/programs/ofg/videos/view/56-Electric-Drag-Racing
>
>
> *
>
> *
>
>
________________________________________________________________________________
| From: | "Robert L. Nuckolls, III" <nuckolls.bob(at)aeroelectric.com> |
| Subject: | Repaired Audio Iso Amp Project |
A few weeks ago I had a conversation with somebody
who was having trouble getting their DIY audio isolation
amp project running.
I offered to troubleshoot the board. It's been laying
on the bench for a time but I got to it this evening
and all is now right with the world.
Problem is that the envelope it came in got separated
from the board and I don't know who to send it back to.
If somebody has been patiently waiting for me to
return their project board, drop me a note and we'll
get the end-game under way.
Bob . . .
________________________________________________________________________________
| From: | Harley <harley(at)AgelessWings.com> |
| Subject: | Re: Off topic electric drag racer |
He switched from lead acid to lithium batteries in 2010...that's
what he used to get his latest world quarter mile speed record.
Kilocycle loaned him the batteries...here's a page from his
website that lists all the features and details of this
Datsun...type of batteries, motor, controller, etc.
www.plasmaboyracing.com/history/2010.php
I remember seeing an article back in the 60s or 70s in Popular
Mechanics or Mechanix Illustrated that outlined installing a jet
engine starter motor to replace the gas engine in a sport car. I
almost tried it as I only had a five mile drive to work...!
Harley
-----------------------------------------------------------------
On 1/22/2011 10:20 PM, Robert Mitchell wrote:
> So, what are the Batteries here?
>
> Bob Mitchell
> L-320
>
>>
>>
>>
>> If a little guy in a home garage can make this, what are
>> all the big car makers doing in all their giant labs?
>> www.opb.org/programs/ofg/videos/view/56-Electric-Drag-Racing
>> <http://www.opb.org/programs/ofg/videos/view/56-Electric-Drag-Racing>
>>
>>
> *
>
>
> *
________________________________________________________________________________
| From: | "Noel Loveys" <noelloveys(at)yahoo.ca> |
| Subject: | tool multitasking |
If you want to see what the off type crimper will do to a D sub din just
try it... but get an extra pin first. I don't think you will try again.
When I trained we were told to try it. We even tried non-ratcheting
crimpers and just about anything else you can imagine. What worked was the
right crimper with the right size jaws for the right pin.
Do you guys use coloured wire or white printed wire and if you use the
printed stuff where do you get it printed?
Noel
From: owner-aeroelectric-list-server(at)matronics.com
[mailto:owner-aeroelectric-list-server(at)matronics.com] On Behalf Of Tim
Andres
Sent: January 22, 2011 12:58 PM
Subject: Re: AeroElectric-List: tool multitasking
I'm cheap also, but I saved several thousand dollars over having this panel
built for me. One of the panel builders qouted me $8K to build the panel and
wire it with power only. That did not include the avionics interconnects. So
I bought the Daniels crimpers with the proper positioners for about $200,
and spent about 3 weeks doing it myself including having the panel CNC cut.
I believe to crimp the HD pins you need the Daniels crimper (or equivalent)
Tim Andres
_____
From: Charlie England <ceengland(at)bellsouth.net>
Sent: Sat, January 22, 2011 7:48:59 AM
Subject: AeroElectric-List: tool multitasking
OK, I'm cheap.
Is there any chance that the B&C RCT-2 crimper will crimp regular &/or
hi-density d-sub pins? If so, I can just buy the RCT-2 instead of both it
and the RCT-3.
Will the RCT-3 crimp the hi-density d-sub pins, or is one of the +$100 tools
needed for those?
Thanks,
Charlie
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utilities such as List Un/Subscription,
Download, 7-Day Browse, Chat, FAQ,
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________________________________________________________________________________
| From: | "Robert L. Nuckolls, III" <nuckolls.bob(at)aeroelectric.com> |
| Subject: | Re: Off topic electric drag racer |
>
>I remember seeing an article back in the 60s or 70s in Popular
>Mechanics or Mechanix Illustrated that outlined installing a jet
>engine starter motor to replace the gas engine in a sport car. I
>almost tried it as I only had a five mile drive to work...!
I think it was Mother Earth magazine that published
a number of articles on gas to electric conversions.
They became popular DIY projects in the 70's and 80's.
I think I recall somebody in the aviation industry
complaining that a particular starter-generator, once
prolific in the used/surplus market was hard to find,
"all those electric car guys snapped them up".
No doubt production electric cars of the future will
have brushless DC motors at each wheel. Drive train
transmissions will evaporate. Indeed, the electric
airplane projects are brushless motors too. These
motors lend themselves to higher voltage operations
which keeps I(squared)R losses down. Lower currents
help offset trade off for Li-Ion with very high energy
densities but higher internal resistances in the cells.
It's a big hat dance around the simple-ideas in physics
that drive the quest for a successful recipe . . . where
success is measured in market acceptance (pure economics).
The cool thing is that we can sit back and watch somebody
else's time/talent/resources being expended at the hat dance.
As with many 'automotive' products that found their way
onto our airplanes, products that arise from these new
technologies will have millions of road-miles on them
before we need to spend out time/talent/resources figuring
how to best benefit us in the air.
The micro-controller was field-tested in millions of
personal computing products and coffee pots before
an EFIS system became a gleam in somebody's eye.
Bob . . .
________________________________________________________________________________
| From: | DeWitt Whittington <dee.whittington(at)gmail.com> |
| Subject: | tool multitasking |
All,
On our Sportsman 2+2 we have been using a Dymo Rhino 3000 printer and
use the Rhino printable heat shrink and labels. It does a smashing
job of allowing us to put any text label on our wires which we do on
each end. The printer prints on the flat heatshrink available in
colors, so we can color code white wire and label in plain English or
any sort of code we want. Not cheap but very professional. We use
some basic wire colors too to generally delineate power/ground/signal wires.
Dee Whittington
At 09:48 AM 1/23/2011, you wrote:
>Do you guys use coloured wire or white printed wire and if you use
>the printed stuff where do you get it printed?
>
>Noel
>
DeWitt (Dee) Whittington
406 N Mulberry St
Richmond, VA 23220-3320
(804) 358-4333 phone and fax
SKYPE: hilltopkid
dee.whittington(at)gmail.com
________________________________________________________________________________
| From: | Robert Borger <rlborger(at)mac.com> |
| Subject: | Re: tool multitasking |
Y'all,
Same solution I was going to suggest. Works great.
Bob Borger
Europa Kit #A221 N914XL, XS Tri-Gear, Intercooled 914, Airmaster C/S Prop
http://www.europaowners.org/forums/gallery2.php?g2_itemId=60232
http://www.biplaneforumgallery.com/index.php?cat=10046
Europa Flying!
3705 Lynchburg Dr.
Corinth, TX 76208
Home: 940-497-2123
Cel: 817-992-1117
On Jan 23, 2011, at 10:32, DeWitt Whittington wrote:
> All,
>
> On our Sportsman 2+2 we have been using a Dymo Rhino 3000 printer and use the
Rhino printable heat shrink and labels. It does a smashing job of allowing us
to put any text label on our wires which we do on each end. The printer prints
on the flat heatshrink available in colors, so we can color code white wire
and label in plain English or any sort of code we want. Not cheap but very professional.
We use some basic wire colors too to generally delineate power/ground/signal
wires.
>
> Dee Whittington
>
>
> At 09:48 AM 1/23/2011, you wrote:
>
>> Do you guys use coloured wire or white printed wire and if you use the printed
stuff where do you get it printed?
>>
>> Noel
>>
> DeWitt (Dee) Whittington
> 406 N Mulberry St
> Richmond, VA 23220-3320
> (804) 358-4333 phone and fax
> SKYPE: hilltopkid
> dee.whittington(at)gmail.com
>
>
>
>
________________________________________________________________________________
| Subject: | Re: Off topic electric drag racer |
| From: | "Jim Berry" <jimberry(at)qwest.net> |
If you liked Bill Dube's electric motorcycle dragster, wait till you see their
new electric Bonneville racer. It will take a longer extension cord though.
Jim Berry
RV-10
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=328054#328054
________________________________________________________________________________
| From: | "Terry Watson" <terry(at)tcwatson.com> |
| Subject: | Off topic electric drag racer |
Way back in the 1950's, my Dad had an electric feed cart that we used on our
mink ranch. The motor was the starter-generator out of a 1928 Dodge. I
remember that when he decided to buy the semi-custom cart from a company in
California, he and Mom drove the station wagon from 100 miles north of
Seattle south, stopping at junk yards along the way looking for '28 Dodge
starter-generators. By the time they got to the manufacturer's facilities in
California, they had enough of them to swap for the feed cart.
The cart had a couple of truck batteries in it. I think I remember it had a
chain drive from the motor to a differential with the drive wheels in the
back, with a single wheel in the front steered by a vertical tiller with a
handle at the top that fit between my legs when I got tall enough. You stood
on a platform at the back that was the forward-reverse and speed control.
Lean forward for forward; back to stop or reverse. Leaning to the side
turned the front wheel. We typically hauled maybe 200 pounds of mink feed on
it. It was a very useful little vehicle around the ranch, but it didn't do
well on rough ground.
Terry
Seattle
From: owner-aeroelectric-list-server(at)matronics.com
[mailto:owner-aeroelectric-list-server(at)matronics.com] On Behalf Of Robert L.
Nuckolls, III
Sent: Sunday, January 23, 2011 7:14 AM
Subject: Re: AeroElectric-List: Off topic electric drag racer
I remember seeing an article back in the 60s or 70s in Popular Mechanics or
Mechanix Illustrated that outlined installing a jet engine starter motor to
replace the gas engine in a sport car. I almost tried it as I only had a
five mile drive to work...!
I think it was Mother Earth magazine that published
a number of articles on gas to electric conversions.
They became popular DIY projects in the 70's and 80's.
I think I recall somebody in the aviation industry
complaining that a particular starter-generator, once
prolific in the used/surplus market was hard to find,
"all those electric car guys snapped them up".
No doubt production electric cars of the future will
have brushless DC motors at each wheel. Drive train
transmissions will evaporate. Indeed, the electric
airplane projects are brushless motors too. These
motors lend themselves to higher voltage operations
which keeps I(squared)R losses down. Lower currents
help offset trade off for Li-Ion with very high energy
densities but higher internal resistances in the cells.
It's a big hat dance around the simple-ideas in physics
that drive the quest for a successful recipe . . . where
success is measured in market acceptance (pure economics).
The cool thing is that we can sit back and watch somebody
else's time/talent/resources being expended at the hat dance.
As with many 'automotive' products that found their way
onto our airplanes, products that arise from these new
technologies will have millions of road-miles on them
before we need to spend out time/talent/resources figuring
how to best benefit us in the air.
The micro-controller was field-tested in millions of
personal computing products and coffee pots before
an EFIS system became a gleam in somebody's eye.
Bob . . .
________________________________________________________________________________
| From: | Bob Falstad <bobair(at)me.com> |
| Subject: | Comm Antenna & SWR Reading -- Too High? |
Bob, et al,
I'm upgrading/replacing the instrument panel in my GlaStar. Part of the project
includes the installation of a Comant CI-122 "bent whip" antenna on the belly
under the baggage compartment area. This antenna will be my "Comm 1" antenna
and will be connected to a Garmin 430W. Because of the composite fuselage,
I installed a 24" x 36" Al ground plane in the belly. The antenna is positioned
so that the entire antenna is "covered" by the ground plane (i.e., the antenna
base is mounted about 12" from the long-axis end of the ground plane. The
antenna is connected (and bonded) to the ground plane with the four stainless
machine screws used to mount the antenna.
A friend who is a ham/EE/PE tested this antenna for SWR and he wasn't very encouraged
by the results. Here are the data:
Equipment:
Bird Watt Meter with (slug?) 5C at 5W, 100 - 250 Mhz
100W Dummy Load: Decibel DB4303G
We used my Yaesu handheld as the transmitter.
Everything was coupled together with BNC connectors.
Test 1: 122.9 MHz (the CTAF at my base): Forward Power: 0.8; Reverse Power:
0.43; VSWR 6.5
Test 2: 125.0 MHz Forward Power: 0.8; Reverse Power: 0.4; VSWR 5.8
Test 3: 130.0 MHz Forward Power: 0.8; Reverse Power: 0.4; VSWR 5.8
We checked the resistance between the four mounting screws and the outside (ground?)
of a BNC connector connected to the antenna. The resistances were all ~0.1
Ohm. The Bird meter was connected directly to the antenna BNC through my
buddy's feedline which appeared to be about 4 feet long. I don't know what type
of coax he used. (The feedline for this antenna to the 430W will be RG-400.)
The test was done in a closed metal hangar. Would that or the proximity of
the antenna to the concrete hangar floor affect the results?
What's your take on this? Should the SWR be significantly lower for good performance
(I plan on flying this plane in IMC)? Are there things that I should/could
do to improve performance before I put the baggage compartment structure
back in and make things much less accessible? Or should this installation/SWR
readings indicate acceptable performance? With these SWR readings, will the
reflected power cause any damage to the Garmin 430W?
Does testing the SWR of a "cat's-whisker" VOR/Loc/GS antenna make sense? I installed
one of those, as well, but the feedline (the yellow tri-ax that comes with
GlaStars) wasn't terminated on the radio end. If it makes sense to do so,
I can go back and test it after I've terminated that feedline.
Thanks in advance.
Best regards,
Bob Falstad
GlaStar N248BF
~310 Hours
________________________________________________________________________________
| From: | Richard Reynolds <richardreynolds(at)cox.net> |
| Subject: | Manifold Pressure Tranducers |
Will the manifold pressure transducers hold vacuum when vacuum tested?
I have one for the Rocky Mountain Instruments uMonitor and one for the Lightspeed
CDI system.
Richard Reynolds
Norfolk VA
RV-6A - N841RV
________________________________________________________________________________
| From: | "Robert L. Nuckolls, III" <nuckolls.bob(at)aeroelectric.com> |
| Subject: | Re: Comm Antenna & SWR Reading -- Too High? |
Test 1: 122.9 MHz (the CTAF at my base): Forward
Power: 0.8; Reverse Power: 0.43; VSWR 6.5
Test 2: 125.0
MHz Forward
Power: 0.8; Reverse Power: 0.4; VSWR 5.8
Test 3: 130.0
MHz Forward
Power: 0.8; Reverse Power: 0.4; VSWR 5.8
We checked the resistance between the four mounting screws and the
outside (ground?) of a BNC connector connected to the antenna. The
resistances were all ~0.1 Ohm. The Bird meter was connected directly
to the antenna BNC through my buddy's feedline which appeared to be
about 4 feet long. I don't know what type of coax he used. (The
feedline for this antenna to the 430W will be RG-400.) The test was
done in a closed metal hangar. Would that or the proximity of the
antenna to the concrete hangar floor affect the results?
Some but I don't think all that much.
What's your take on this? Should the SWR be significantly lower for
good performance (I plan on flying this plane in IMC)? Are there
things that I should/could do to improve performance before I put the
baggage compartment structure back in and make things much less
accessible? Or should this installation/SWR readings indicate
acceptable performance?
Could be. We need to consider the effects of making
measurements on the transmitter end of a piece of coax
when studying the characteristics of a particular
load (antenna).
The only time a piece of coax will show 1:1 SWR is
when the OTHER end is terminated in a load having the
same characteristic impedance. In this case 50 ohms
resistive and no reactive component.
Consider also that the antenna's characteristics
measured at the base may never be exactly 50 ohms
and it may include reactive components (inductance/
capacitance) as well.
Just went to the bench and fabricated this test
article.
Emacs!
It's 22" of 12AWG copper soldered to a BNC chassis connector
mounted to approximate center of a copper sheet 24 x 36
inches.
The investigative instrument of choice is the MFJ-259
antenna analyzer. Here is a chart of measurement results:
Emacs!
A fine wire, 1/4 wave radiator has a resonance base impedance that
is quite low. As you can see, at 126 MHz and minimized feedline,
the reactive component of this antenna went down to 0 ohms (resonance)
and the resistive component was about 12 ohms. Hmmm . . . 12/50
explains the 4:1 SWR reading that was observed. So in terms of best
performance (resonance) this antenna is rather crippled for accepting
all the power that a 50 ohm feedline has to offer.
At the extreme ends of the comm band, the reactive and resistive
components did their expected hat dances with SWR readings that
never got better than about 3:1 at any frequency.
Okay, let's put a piece of "test coax" between the antenna and
instrument. SWR figures got better over the range of interest although
resistive and reactive components became a bit more agitated.
This is because of the effects of frequency on a mismatched
piece of coax can be profound in terms of what is viewed
looking into the same end as your transceiver. We take advantage
of these "transforming" effects offered by mis-matched transmission
lines but in the case before us, there's no particular advantage
to be gained. The question to be answered is "how much practical
difference does it make?"
Interestingly enough, the longer a transmission line, the
BETTER things get. This is because of losses in the line.
You can hook your transponder to one end of a 1000' spool
of the best coax out there and it wouldn't know if the
other end was open, shorted, or had a good antenna on it.
Even if there WAS a good antenna on it, no practical amount
of energy would even reach it due to transmission line
losses.
So back to your quest and questions:
The effective testing for antenna systems generaly
assumes that the antenna itself is okay. It MAY have some
pretty squirrely characteristics . . . but that's how
monopole-quarterwave antennas are. So is your
feedline good? Put a dummy load on the antenna end of
the feedline and check SWR over frequency range of interest
from the transceiver end.
Since you've terminated the feedline in a value it
LIKES, the SWR should be 1:1 over full frequency
range. If the feed path is compromised with opens
or shorts, the SWR will not be 1:1 at any frequency
and will wobble all over the place as frequency
changes.
But if the antenna is not damaged, the mounting
hardware is tight, the ground-plane moderately
adequate, then consider it good.
Now, it is useful to make SWR observations over
range of interest when the installation is new
and write them down. Use them as a benchmark for
future reference if you ever have a reason to
question antenna performance.
With these SWR readings, will the reflected power cause any damage to
the Garmin 430W?
No. Modern transceivers have built in protection for
poor performing loads . . . up to and including shorted
and open transmission lines.
Does testing the SWR of a "cat's-whisker" VOR/Loc/GS antenna make sense?
Sure. But keep in mind that SWR is a measure of the antenna's
ability to accept/deliver energy and says nothing about
operational performance. I've seen antennas with 'terrible'
SWR out-perform antennas with 'excellent' swr but for reasons
other than impedance matching. Do separate dummy loaded
and antenna loaded measurements of the as-installed antenna
and associated feedline.
Hooking any sort of analyzer to the antenna itself will
yield good data but it will be data that has little or
no significance in terms of performance.
Given what we know of your system based on data you cited,
I have no reason to suspect that anything is amiss. It
would be good to get forward/reverse power measurements
of the as-installed antenna and feedline. Check THESE
numbers against manufacturer's limits in the installation
manual.
A caveat: Your own results may vary. Some commercial
antennas MAY have impedance transformation networks built
in that are intended to improve power transfer over the
range of interest. Further, the test I just demonstrated
is a fine-wire antenna . . . sharply resonant compared to
say a piece of 1/2" tubing which would be broader (and
harder to mount plus more drag) Shark fin antennas on
air-transport category airplanes have impedance matching
in the base and 'broadness' in the radiating components.
Finally, keep in mind that Cessna and others fitted their
products with antennas that looked a lot like this:
Emacs!
Tens of thousands of antennas went out the factory
doors with this or similar configuration. This was
in a time when radios were MUCH less capable in terms
of sensitivity and signal/noise ratio of modern
avionics.
The upshot is that it's more important to BE CONNECTED
to what ever antenna you have than it is to massage
measured or perceived performance. No antenna is bad,
any antenna is probably good.
Bob . . .
________________________________________________________________________________
| From: | "Robert L. Nuckolls, III" <nuckolls.bob(at)aeroelectric.com> |
| Subject: | Re: Manifold Pressure Tranducers |
At 04:29 PM 1/23/2011, you wrote:
>
>
>Will the manifold pressure transducers hold vacuum when vacuum tested?
>
>I have one for the Rocky Mountain Instruments uMonitor and one for
>the Lightspeed CDI system.
I've never encountered any pressure transducer that
was not 'air tight' to the environment. It sorta
hoses performance. Yes, you can test by pulling a
vacuum and watching for leaks.
Bob . . .
________________________________________________________________________________
| From: | "Noel Loveys" <noelloveys(at)yahoo.ca> |
| Subject: | Off topic electric drag racer |
Snip
No doubt production electric cars of the future will
have brushless DC motors at each wheel. Drive train
transmissions will evaporate. Indeed, the electric
airplane projects are brushless motors too. These
motors lend themselves to higher voltage operations
which keeps I(squared)R losses down.
. Years ago I think it was Popular Science had a story on a vehicle
with that particular drive. Theirs was a 6X6.
Snip
The cool thing is that we can sit back and watch somebody
else's time/talent/resources being expended at the hat dance.
As with many 'automotive' products that found their way
onto our airplanes, products that arise from these new
technologies will have millions of road-miles on them
before we need to spend out time/talent/resources figuring
how to best benefit us in the air.
Bob, I'm a bit surprised you didn't mention the serious work thousands of
amateur radio buffs did on digital controls let alone digital emissions. I
still remember sending full colour photographs around the world through a 1
khz bandwidth.
Noel
________________________________________________________________________________
| From: | "Noel Loveys" <noelloveys(at)yahoo.ca> |
| Subject: | tool multitasking |
Great to hear.
Problem with coloured wires is of course getting a fool up between a red
wire with a green trace and a red wire with a blue trace (colour blindness)
and or the red wire with the yellow trace and the yellow wire with the red
trace.
I like number codes... Eg. Charging circuits may be all marked 1- the
next number in the code will be the piece in the run so if you have a
firewall through put the second piece of wire to your regulator/rectifier
could be 1-2. Then from the rectifier to the master switches could be
1-2-1. Makes things so easy to follow on a schematic as well as in the
plane. The white colour allows you to see any heat problems.
Being a bit old school... Make that a lot old school... I'd like to see the
inventor of nylon tie wraps severely flogged with a piece of his own tie
wrap. I wish I had a penny for every time I gashed my hands or arms on that
stuff. Wax string and Cora Seal is a lot neater but does take a bit more
time to do properly.
Noel
From: owner-aeroelectric-list-server(at)matronics.com
[mailto:owner-aeroelectric-list-server(at)matronics.com] On Behalf Of DeWitt
Whittington
Sent: January 23, 2011 1:03 PM
Subject: RE: AeroElectric-List: tool multitasking
All,
On our Sportsman 2+2 we have been using a Dymo Rhino 3000 printer and use
the Rhino printable heat shrink and labels. It does a smashing job of
allowing us to put any text label on our wires which we do on each end. The
printer prints on the flat heatshrink available in colors, so we can color
code white wire and label in plain English or any sort of code we want. Not
cheap but very professional. We use some basic wire colors too to generally
delineate power/ground/signal wires.
Dee Whittington
At 09:48 AM 1/23/2011, you wrote:
Do you guys use coloured wire or white printed wire and if you use the
printed stuff where do you get it printed?
Noel
DeWitt (Dee) Whittington
406 N Mulberry St
Richmond, VA 23220-3320
(804) 358-4333 phone and fax
SKYPE: hilltopkid
dee.whittington(at)gmail.com
________________________________________________________________________________
| From: | DeWitt Whittington <dee.whittington(at)gmail.com> |
| Subject: | tool multitasking |
No, Noel,
We do not use colored wires with color traces. Only easy to
distinguish solid colors and only a few of those. The detail we leave
to the plain English or as desired coded printed heat shrink labels
placed everywhere as needed.
Agree cord is the best, but our Ty-Wraps (we only use that brand by
Thomas & Betts) we cut totally flush with a special pair of diagonal
cutters easily available on the market. No sliced hands so far.
Dee
At 07:04 PM 1/23/2011, you wrote:
>Great to hear.
>
>Problem with coloured wires is of course getting a fowl up between a
>red wire with a green trace and a red wire with a blue trace (colour
>blindness) and or the red wire with the yellow trace and the yellow
>wire with the red trace.
>
>I like number codes... Eg. Charging circuits may be all marked
>1- the next number in the code will be the piece in the run so if
>you have a firewall through put the second piece of wire to your
>regulator/rectifier could be 1-2. Then from the rectifier to the
>master switches could be 1-2-1. Makes things so easy to follow on a
>schematic as well as in the plane. The white colour allows you to
>see any heat problems.
>
>Being a bit old school... Make that a lot old school... I'd like to
>see the inventor of nylon tie wraps severely flogged with a piece of
>his own tie wrap. I wish I had a penny for every time I gashed my
>hands or arms on that stuff. Wax string and Cora Seal is a lot
>neater but does take a bit more time to do properly.
>
>Noel
>
>From: owner-aeroelectric-list-server(at)matronics.com
>[mailto:owner-aeroelectric-list-server(at)matronics.com] On Behalf Of
>DeWitt Whittington
>Sent: January 23, 2011 1:03 PM
>To: aeroelectric-list(at)matronics.com
>Subject: RE: AeroElectric-List: tool multitasking
>
>All,
>
>On our Sportsman 2+2 we have been using a Dymo Rhino 3000 printer
>and use the Rhino printable heat shrink and labels. It does a
>smashing job of allowing us to put any text label on our wires which
>we do on each end. The printer prints on the flat heatshrink
>available in colors, so we can color code white wire and label in
>plain English or any sort of code we want. Not cheap but very
>professional. We use some basic wire colors too to generally
>delineate power/ground/signal wires.
>
>Dee Whittington
>
>
>At 09:48 AM 1/23/2011, you wrote:
>
>
>Do you guys use coloured wire or white printed wire and if you use
>the printed stuff where do you get it printed?
>
>Noel
>
>DeWitt (Dee) Whittington
>406 N Mulberry St
>Richmond, VA 23220-3320
>(804) 358-4333 phone and fax
>SKYPE: hilltopkid
>dee.whittington(at)gmail.com
>
>
>http://www.matronics.com/Navigator?AeroElectric-List
>
>
>http://forums.matronics.com
>
>
>http://www.matronics.com/contribution
>
>
DeWitt (Dee) Whittington
406 N Mulberry St
Richmond, VA 23220-3320
(804) 358-4333 phone and fax
SKYPE: hilltopkid
dee.whittington(at)gmail.com
________________________________________________________________________________
| From: | "Noel Loveys" <noelloveys(at)yahoo.ca> |
| Subject: | tool multitasking |
Any tie wraps can be made safe by simply sanding the sharp ends where the
excess gets cut off. Too bad not many people take the seconds required to
do that. You've been luckier than I have... and I have scars to prove it!
Noel
From: owner-aeroelectric-list-server(at)matronics.com
[mailto:owner-aeroelectric-list-server(at)matronics.com] On Behalf Of DeWitt
Whittington
Sent: January 23, 2011 8:56 PM
Subject: RE: AeroElectric-List: tool multitasking
No, Noel,
We do not use colored wires with color traces. Only easy to distinguish
solid colors and only a few of those. The detail we leave to the plain
English or as desired coded printed heat shrink labels placed everywhere as
needed.
Agree cord is the best, but our Ty-Wraps (we only use that brand by Thomas &
Betts) we cut totally flush with a special pair of diagonal cutters easily
available on the market. No sliced hands so far.
Dee
At 07:04 PM 1/23/2011, you wrote:
Great to hear.
Problem with coloured wires is of course getting a fowl up between a red
wire with a green trace and a red wire with a blue trace (colour blindness)
and or the red wire with the yellow trace and the yellow wire with the red
trace.
I like number codes... Eg. Charging circuits may be all marked 1- the
next number in the code will be the piece in the run so if you have a
firewall through put the second piece of wire to your regulator/rectifier
could be 1-2. Then from the rectifier to the master switches could be
1-2-1. Makes things so easy to follow on a schematic as well as in the
plane. The white colour allows you to see any heat problems.
Being a bit old school... Make that a lot old school... I'd like to see the
inventor of nylon tie wraps severely flogged with a piece of his own tie
wrap. I wish I had a penny for every time I gashed my hands or arms on that
stuff. Wax string and Cora Seal is a lot neater but does take a bit more
time to do properly.
Noel
From: owner-aeroelectric-list-server(at)matronics.com [
mailto:owner-aeroelectric-list-server(at)matronics.com
] On Behalf Of DeWitt
Whittington
Sent: January 23, 2011 1:03 PM
Subject: RE: AeroElectric-List: tool multitasking
All,
On our Sportsman 2+2 we have been using a Dymo Rhino 3000 printer and use
the Rhino printable heat shrink and labels. It does a smashing job of
allowing us to put any text label on our wires which we do on each end. The
printer prints on the flat heatshrink available in colors, so we can color
code white wire and label in plain English or any sort of code we want. Not
cheap but very professional. We use some basic wire colors too to generally
delineate power/ground/signal wires.
Dee Whittington
At 09:48 AM 1/23/2011, you wrote:
Do you guys use coloured wire or white printed wire and if you use the
printed stuff where do you get it printed?
Noel
DeWitt (Dee) Whittington
406 N Mulberry St
Richmond, VA 23220-3320
(804) 358-4333 phone and fax
SKYPE: hilltopkid
dee.whittington(at)gmail.com
<http://www.matronics.com/Navigator?AeroElectric-List>
http://www.matronics.com/Navigator?AeroElectric-List
<http://forums.matronics.com/>
http://forums.matronics.com
<http://www.matronics.com/contribution>
http://www.matronics.com/contribution
DeWitt (Dee) Whittington
406 N Mulberry St
Richmond, VA 23220-3320
(804) 358-4333 phone and fax
SKYPE: hilltopkid
dee.whittington(at)gmail.com
________________________________________________________________________________
| From: | "Robert L. Nuckolls, III" <nuckolls.bob(at)aeroelectric.com> |
| Subject: | Off topic electric drag racer |
>
>Bob, I'm a bit surprised you didn't mention the serious work
>thousands of amateur radio buffs did on digital controls let alone
>digital emissions. I still remember sending full colour photographs
>around the world through a 1 khz bandwidth.
Yeah, there was a lot of packet work begin done in the late '80s
and slow-scan tv predates that by 10 years or more. There
are no doubt thousands of examples of 'leading edge' process
and technology that laid the groundwork for the future
of today's product. But we were talking about systems
and components that provide low risk, useful services in
the airplane.
Development costs need to be amortized over great
numbers for them to become insignificant. Little
airplanes don't represent much of a market! Our
demonstrated reservoir of successful recipes
have come from the volume consumer markets.
The SVLA battery has been around commercially
since 1970 but it wasn't until 1990 that they got a real
toe holed in OBAM aviation . . . and only then after
the un-interruptible power supply market bloomed.
When LORAN was still king and a panel mounted GPS was
prohibitively expensive, I bought a perfectly serviceable
GPS for airplanes from a Boat US catalog for $200.
I didn't mean to 'slight' any of the guys who
did it first. But doing if first doesn't immediately
and directly translate into useful, cost-effective
product.
Bob . . .
________________________________________________________________________________
| From: | "Robert L. Nuckolls, III" <nuckolls.bob(at)aeroelectric.com> |
| Subject: | tool multitasking |
> . . . we cut totally flush with a special pair of diagonal cutters
> easily available on the market. No sliced hands so far.
I suspect the "special" cutters are commonly referred to
as jewelers flush cutters. The come in a variety of
qualities and prices. The ones I've been using around
here for awhile are.
http://tinyurl.com/4nptpy5
These are not yer granpa's fence wire tool. Apply
these judiciously.
Bob . . .
________________________________________________________________________________
| From: | "Robert L. Nuckolls, III" <nuckolls.bob(at)aeroelectric.com> |
| Subject: | Re: Comm Antenna & SWR Reading -- Too High? |
At 02:27 PM 1/23/2011, you wrote:
>
>Bob, et al,
>
>I'm upgrading/replacing the instrument panel in my GlaStar. Part of
>the project includes the installation of a Comant CI-122 "bent whip"
>antenna on the belly under the baggage compartment area.
I did some searching for manufacturer's specs on the
CI-122 and found VSWR specs of both 2:1 and 3:1 maximum.
These kinds of figures imply some sort of impedance matching
hardware in the base of the antenna. It would be interesting
to do an ohmmeter test from center pin on the antenna's connector
and ground. If is shows a 'short', I suspect that some sort
of matching system is installed.
If that's true, then the values you were reading for
the tests are perhaps more worrisome. Get your ohmmeter
out an take a peek.
Bob . . .
________________________________________________________________________________
| Subject: | Re: Comm Antenna & SWR Reading -- Too High? |
| From: | Dj Merrill <deej(at)deej.net> |
On 1/23/2011 2:27 PM, Bob Falstad wrote:
>
> Test 1: 122.9 MHz (the CTAF at my base): Forward Power: 0.8; Reverse Power:
0.43; VSWR 6.5
> Test 2: 125.0 MHz Forward Power: 0.8; Reverse Power: 0.4; VSWR 5.8
> Test 3: 130.0 MHz Forward Power: 0.8; Reverse Power: 0.4; VSWR 5.8
Hi Bob,
In my opinion, anything greater than 2:1 would be unacceptable for
use in my ham station or my airplane. The very high SWR you have
indicates a significant loss of signal. At an SWR of 6.5 to 1, you are
losing over 50% of your radio signal (ie, less than half of your signal
is being transmitted out the antenna, and the rest is being reflected
back into your radio).
Google SWR for a ton of info on the topic, with a good reference at
http://en.wikipedia.org/wiki/Standing_wave_ratio (Scroll down to the
Practical Applications section)
and an online calculator showing percent of loss at:
http://www.csgnetwork.com/vswrlosscalc.html
6.5:1 indicates you may be losing 53% of your signal. 2:1 is only
11%. The better (lower) the SWR, the better the performance, and IMHO
if I were going IMC with it, I'd want the best performance I could get.
Will it work at 6.5:1? Yes, it will. Is it "the best we know how
to do"? In my opinion, no. I'd ask your Ham buddy to look it over to
see if anything can be done to help.
Some things I can think of to try:
- With the Glastar's metal cage and landing legs, if the antenna is
installed close enough to either that might have an effect on SWR. Even
the rudder and elevator cables running down the center of the baggage
area could possibly have an effect. Does the SWR change of your move
the rudder or the control stick for the elevator? You might try taking
the antenna out of the plane, installing it on a ground plane on your
work bench and test it there to see if you can duplicate the results.
- The Glastar has a fairly thick fiberglass shell. When you
installed the antenna, did you carve out the fiberglass so that the
antenna is touching the ground plane, or did you install it such that
there is a gap between the antenna and ground plane (ie, the thickness
of the fiberglass)? This could have a significant difference in SWR if
the antenna is supposed to be mounted directly to the ground plane with
no gap, as in the case of a metal plane.
- Is there an adjustment on the antenna itself?
- Double check that all of your coax lines are good, and there are
no stray pieces of the shield material that might be shorting out to the
center conductor.
Good luck! Please report back and let us know what you find if you
decide to look into it further.
-Dj
--
Dj Merrill - N1JOV
Glastar Sportsman 2+2 Builder #7118 N421DJ - http://deej.net/sportsman/
Please use Netiquette Guidelines http://tools.ietf.org/html/rfc1855
Kindly TRIM your email replies and post AFTER the relevant text
________________________________________________________________________________
| From: | Robert Mitchell <rmitch1(at)hughes.net> |
| Subject: | Re: Off topic electric drag racer |
And, don't forget all the free hand me down benefits we get from NASA thru taxpayer
dollars.
Bob Mitchell
Sent from my iPad
On Jan 23, 2011, at 6:39 PM, "Robert L. Nuckolls, III"
wrote:
>
>
>>
>> Bob, I'm a bit surprised you didn't mention the serious work thousands of amateur
radio buffs did on digital controls let alone digital emissions. I still
remember sending full colour photographs around the world through a 1 khz bandwidth.
>
> Yeah, there was a lot of packet work begin done in the late '80s
> and slow-scan tv predates that by 10 years or more. There
> are no doubt thousands of examples of 'leading edge' process
> and technology that laid the groundwork for the future
> of today's product. But we were talking about systems
> and components that provide low risk, useful services in
> the airplane.
>
> Development costs need to be amortized over great
> numbers for them to become insignificant. Little
> airplanes don't represent much of a market! Our
> demonstrated reservoir of successful recipes
> have come from the volume consumer markets.
>
> The SVLA battery has been around commercially
> since 1970 but it wasn't until 1990 that they got a real
> toe holed in OBAM aviation . . . and only then after
> the un-interruptible power supply market bloomed.
>
> When LORAN was still king and a panel mounted GPS was
> prohibitively expensive, I bought a perfectly serviceable
> GPS for airplanes from a Boat US catalog for $200.
>
> I didn't mean to 'slight' any of the guys who
> did it first. But doing if first doesn't immediately
> and directly translate into useful, cost-effective
> product.
>
>
> Bob . . .
>
>
>
>
________________________________________________________________________________
| From: | "Noel Loveys" <noelloveys(at)yahoo.ca> |
| Subject: | Off topic electric drag racer |
Too bad about the LORAN... It has a few advantages over GPS. It's cheaper
and it's on the ground where it is somewhat more protected from things man
made and otherwise hurtling through space. I remember once when a C-band
satellite was knocked into by a meteor. For a period of time there was a
loss of signal. It could have been much worse as all geostationary
satellites are in a over the equator. I hope we never get in the situation
where we could benefit by those now lost advantages.
Noel
-----Original Message-----
From: owner-aeroelectric-list-server(at)matronics.com
[mailto:owner-aeroelectric-list-server(at)matronics.com] On Behalf Of Robert L.
Nuckolls, III
Sent: January 23, 2011 10:09 PM
Subject: RE: AeroElectric-List: Off topic electric drag racer
>
>Bob, I'm a bit surprised you didn't mention the serious work
>thousands of amateur radio buffs did on digital controls let alone
>digital emissions. I still remember sending full colour photographs
>around the world through a 1 khz bandwidth.
Yeah, there was a lot of packet work begin done in the late '80s
and slow-scan tv predates that by 10 years or more. There
are no doubt thousands of examples of 'leading edge' process
and technology that laid the groundwork for the future
of today's product. But we were talking about systems
and components that provide low risk, useful services in
the airplane.
Development costs need to be amortized over great
numbers for them to become insignificant. Little
airplanes don't represent much of a market! Our
demonstrated reservoir of successful recipes
have come from the volume consumer markets.
The SVLA battery has been around commercially
since 1970 but it wasn't until 1990 that they got a real
toe holed in OBAM aviation . . . and only then after
the un-interruptible power supply market bloomed.
When LORAN was still king and a panel mounted GPS was
prohibitively expensive, I bought a perfectly serviceable
GPS for airplanes from a Boat US catalog for $200.
I didn't mean to 'slight' any of the guys who
did it first. But doing if first doesn't immediately
and directly translate into useful, cost-effective
product.
Bob . . .
________________________________________________________________________________
| From: | "Noel Loveys" <noelloveys(at)yahoo.ca> |
| Subject: | tool multitasking |
Use the same cuts. But most of the other guys I know are using regular
sidecuts and they are not too careful about trimming/sanding the ends of the
tie wraps.
Noel
From: owner-aeroelectric-list-server(at)matronics.com
[mailto:owner-aeroelectric-list-server(at)matronics.com] On Behalf Of Robert L.
Nuckolls, III
Sent: January 23, 2011 10:15 PM
Subject: RE: AeroElectric-List: tool multitasking
. . . we cut totally flush with a special pair of diagonal cutters easily
available on the market. No sliced hands so far.
I suspect the "special" cutters are commonly referred to
as jewelers flush cutters. The come in a variety of
qualities and prices. The ones I've been using around
here for awhile are.
http://tinyurl.com/4nptpy5
These are not yer granpa's fence wire tool. Apply
these judiciously.
Bob . . .
________________________________________________________________________________
| From: | "Noel Loveys" <noelloveys(at)yahoo.ca> |
| Subject: | Comm Antenna & SWR Reading -- Too High? |
Bob what did you use to measure the forward and reverse power? A bird or
just a regular SWR meter?
Noel
-----Original Message-----
From: owner-aeroelectric-list-server(at)matronics.com
[mailto:owner-aeroelectric-list-server(at)matronics.com] On Behalf Of Dj
Merrill
Sent: January 23, 2011 11:51 PM
Subject: Re: AeroElectric-List: Comm Antenna & SWR Reading -- Too High?
On 1/23/2011 2:27 PM, Bob Falstad wrote:
>
> Test 1: 122.9 MHz (the CTAF at my base): Forward Power: 0.8;
Reverse Power: 0.43; VSWR 6.5
> Test 2: 125.0 MHz Forward
Power: 0.8; Reverse Power: 0.4; VSWR 5.8
> Test 3: 130.0 MHz Forward
Power: 0.8; Reverse Power: 0.4; VSWR 5.8
Hi Bob,
In my opinion, anything greater than 2:1 would be unacceptable for
use in my ham station or my airplane. The very high SWR you have
indicates a significant loss of signal. At an SWR of 6.5 to 1, you are
losing over 50% of your radio signal (ie, less than half of your signal
is being transmitted out the antenna, and the rest is being reflected
back into your radio).
Google SWR for a ton of info on the topic, with a good reference at
http://en.wikipedia.org/wiki/Standing_wave_ratio (Scroll down to the
Practical Applications section)
and an online calculator showing percent of loss at:
http://www.csgnetwork.com/vswrlosscalc.html
6.5:1 indicates you may be losing 53% of your signal. 2:1 is only
11%. The better (lower) the SWR, the better the performance, and IMHO
if I were going IMC with it, I'd want the best performance I could get.
Will it work at 6.5:1? Yes, it will. Is it "the best we know how
to do"? In my opinion, no. I'd ask your Ham buddy to look it over to
see if anything can be done to help.
Some things I can think of to try:
- With the Glastar's metal cage and landing legs, if the antenna is
installed close enough to either that might have an effect on SWR. Even
the rudder and elevator cables running down the center of the baggage
area could possibly have an effect. Does the SWR change of your move
the rudder or the control stick for the elevator? You might try taking
the antenna out of the plane, installing it on a ground plane on your
work bench and test it there to see if you can duplicate the results.
- The Glastar has a fairly thick fiberglass shell. When you
installed the antenna, did you carve out the fiberglass so that the
antenna is touching the ground plane, or did you install it such that
there is a gap between the antenna and ground plane (ie, the thickness
of the fiberglass)? This could have a significant difference in SWR if
the antenna is supposed to be mounted directly to the ground plane with
no gap, as in the case of a metal plane.
- Is there an adjustment on the antenna itself?
- Double check that all of your coax lines are good, and there are
no stray pieces of the shield material that might be shorting out to the
center conductor.
Good luck! Please report back and let us know what you find if you
decide to look into it further.
-Dj
--
Dj Merrill - N1JOV
Glastar Sportsman 2+2 Builder #7118 N421DJ - http://deej.net/sportsman/
Please use Netiquette Guidelines http://tools.ietf.org/html/rfc1855
Kindly TRIM your email replies and post AFTER the relevant text
________________________________________________________________________________
| From: | "Noel Loveys" <noelloveys(at)yahoo.ca> |
| Subject: | Off topic electric drag racer |
Reminds me of the story about the money NASA spent to build a ball point pen
for space... The Russians used a pencil. Now what was not said. The
pencil leaves dust floating around every time it is used The point can break
off and jam equipment and on at least one occasion the pen was disassembled
and used to actually save a mission. On the surface it looked foolish but
in the long run it was money well spent.
Noel
-----Original Message-----
From: owner-aeroelectric-list-server(at)matronics.com
[mailto:owner-aeroelectric-list-server(at)matronics.com] On Behalf Of Robert
Mitchell
Sent: January 24, 2011 12:34 AM
Subject: Re: AeroElectric-List: Off topic electric drag racer
And, don't forget all the free hand me down benefits we get from NASA thru
taxpayer dollars.
Bob Mitchell
Sent from my iPad
On Jan 23, 2011, at 6:39 PM, "Robert L. Nuckolls, III"
wrote:
>
>
>>
>> Bob, I'm a bit surprised you didn't mention the serious work thousands of
amateur radio buffs did on digital controls let alone digital emissions. I
still remember sending full colour photographs around the world through a 1
khz bandwidth.
>
> Yeah, there was a lot of packet work begin done in the late '80s
> and slow-scan tv predates that by 10 years or more. There
> are no doubt thousands of examples of 'leading edge' process
> and technology that laid the groundwork for the future
> of today's product. But we were talking about systems
> and components that provide low risk, useful services in
> the airplane.
>
> Development costs need to be amortized over great
> numbers for them to become insignificant. Little
> airplanes don't represent much of a market! Our
> demonstrated reservoir of successful recipes
> have come from the volume consumer markets.
>
> The SVLA battery has been around commercially
> since 1970 but it wasn't until 1990 that they got a real
> toe holed in OBAM aviation . . . and only then after
> the un-interruptible power supply market bloomed.
>
> When LORAN was still king and a panel mounted GPS was
> prohibitively expensive, I bought a perfectly serviceable
> GPS for airplanes from a Boat US catalog for $200.
>
> I didn't mean to 'slight' any of the guys who
> did it first. But doing if first doesn't immediately
> and directly translate into useful, cost-effective
> product.
>
>
> Bob . . .
>
>
>
>
________________________________________________________________________________
| From: | Ron Quillin <rjquillin(at)cox.net> |
| Subject: | Re: Comm Antenna & SWR Reading -- Too High? |
Has there been any consideration given to ground proximity to the antenna?
Some years ago I too measured VSWR on a belly mounted bent whip of a
Bellanca Viking while on the ground and got rather disappointing
results, however the same test repeated with the aircraft airborne
yielded startlingly different, and acceptable, readings.
At 19:20 1/23/2011, you wrote:
>
>On 1/23/2011 2:27 PM, Bob Falstad wrote:
>>Test 1: 122.9 MHz (the CTAF at my base): Forward
>>Power: 0.8; Reverse Power: 0.43; VSWR 6.5
>>Test 2: 125.0
>>MHz Forward
>>Power: 0.8; Reverse Power: 0.4; VSWR 5.8
>>Test 3: 130.0
>>MHz Forward
>>Power: 0.8; Reverse Power: 0.4; VSWR 5.8
>
>Hi Bob,
> In my opinion, anything greater than 2:1 would be unacceptable
> for use in my ham station or my airplane. The very high SWR you
> have indicates a significant loss of signal. At an SWR of 6.5 to
> 1, you are losing over 50% of your radio signal (ie, less than half
> of your signal is being transmitted out the antenna, and the rest
> is being reflected back into your radio).
________________________________________________________________________________
| Subject: | Re: tool multitasking |
| From: | "jonlaury" <jonlaury(at)impulse.net> |
For wire marking, I tried a Brother lableler, but the tape is expensive and it
wastes a lot and it's a bit large. Then I tried printing 8 pt labels on paper
and cutting them out as I needed and slipped under clear heatshrink. But I always
ended up needing a label at the hangar that I hadn't thought of at home.
I ended up hand-printing the lablel that I wanted on 1/8" masking tape (auto body
shop supply) that just goes around awg 20 and slipping under heat shrink. That
ended up being the cheapest, quickest, neatest and most effective. Solid color
heat shrink for coding. Labels on both ends indicate origination, device
served, leg, wire size.
My Franklin engine logs came from Poland, hand printed in a beautiful style, the
machined parts of the engine had a similar hand-etched style. It reminded me
that these engines were actually built by a person. I like that same look on
my wiring and ditto for the poly-tape tied wire run bundles FWF.
John
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=328223#328223
________________________________________________________________________________
| From: | Bob Falstad <bobair(at)me.com> |
| Subject: | Re: "Emacs!" in Response: Was Comm Antenna & SWR Reading |
Bob,
Many thanks for your quick and detailed response. However, your response had three
"Emacs!" in it that appear to refer to graphics that I can't view. I searched
the AeroElectric lists archives and the most detailed message re "Emacs!"
was yours dated July 31, 2009. I couldn't find any other relevant messages
on how to view your graphics/photos.
I'm using a Macbook with OS 10.4.6 (Snow Leopard) that also has a full install
of Windows XP in it. I opened your reply in three different browsers -- Safari,
Firefox and Internet Explorer 8 but no joy.
Any thoughts on how I can retrieve/view your "Emacs!" graphical inserts?
Best regards,
Bob Falstad
________________________________________________________________________________
| From: | Jeff Page <jpx(at)qenesis.com> |
| Subject: | Re: tool multitasking |
The printer seems reasonable at $75.
However, 5 feet of heatshrink for $28 is quite expensive !
Has anyone found a more competitive source ?
I assume you cannot load standard heatshrink in the unit ?
Thanks,
Jeff Page
Dream Aircraft Tundra #10
> On our Sportsman 2+2 we have been using a Dymo Rhino 3000 printer
> and use the Rhino printable heat shrink and labels. It does a
> smashing job of allowing us to put any text label on our wires which
> we do on each end. The printer prints on the flat heatshrink
> available in colors, so we can color code white wire and label in
> plain English or any sort of code we want. Not cheap but very
> professional. We use some basic wire colors too to generally
> delineate power/ground/signal wires.
> Dee Whittington
________________________________________________________________________________
| From: | paul wilson <pwmac(at)sisna.com> |
| Subject: | Comm Antenna & SWR Reading |
I am not Bob , but I use a forward/reflected SWR meter. Its a low
cost unit that did not have serious badmouthing from the Ham guys.
MFJ-862 SWR/Wattmeter. It has a 30 and 300w max range setting
PaulW
========
At 08:14 AM 1/24/2011, Noel Loveys wrote:
>
>Bob what did you use to measure the forward and reverse power? A bird or
>just a regular SWR meter?
>
>Noel
________________________________________________________________________________
| From: | Bob Falstad <bobair(at)me.com> |
| Subject: | Comm Antenna & SWR Reading: Additional Info |
Bob, et al,
Here is some additional information:
To Bob's inquiry "It would be interesting to do an ohmmeter test from center pin
on the antenna's connector and ground. If is shows a 'short', I suspect that
some sort of matching system is installed.", my ohmmeter showed a complete open
between the center pin and the shell of the BNC connector on the antenna base.
To Dj Merrill's questions:
1. The antenna base is about 16" aft of the aft portion of the GlaStar's metal
cage steel tubing and about 54" aft of the main gear legs (my 'Star is a taildragger).
The bent whip portion of the antenna trails aft, obviously, from the
base. We didn't check the SWR while moving the empennage control cables --
they run about 3" - 4" above the antenna base. (But I just installed in the tail
cone about 18" above the control cables a magnetometer for a Dynon EFIS and
the indicated heading didn't change when I moved the elevator controls if that
info is relevant to this discussion.)
2. The antenna base is installed on the exterior surface of the composite fuselage
and the ground plane is on the inside surface. They are about 7/16" of an
inch apart and, as I mentioned before, electrically bonded by the four stainless
machine screws that mount the antenna to the airplane. I haven't researched
whether the antenna must be mounted directly on the ground plane -- if so,
that will be an issue since some composite surgery will be required that I'd
really rather avoid.
3. I didn't see any adjustment on the antenna itself.
Based on the responses, it looks like I've got some more tweaking/testing to do.
Specifically:
Re-test the antennas (including the cat's whisker) and their feed lines separately,
and then together after I've got the feed lines cut to final length and with
their final BNC connectors in place. The RG-400 feed line from the Comm 1
antenna to the Garmin 430W will be about 10' long. I can vary (i.e., lengthen)
that length if it will help performance. Is there a rule of thumb in how long
to make antenna feed lines for optimum performance?
When re-running the tests, would it make any difference to use a more powerful
transmitter than my little hand-held? Or should I stick with what I used originally
to eliminate one more variable that might affect the follow-on data?
Thanks for the helpful advice.
Best regards,
Bob
________________________________________________________________________________
| From: | "Robert L. Nuckolls, III" <nuckolls.bob(at)aeroelectric.com> |
| Subject: | Re: "Emacs!" in Response: Was Comm Antenna & |
SWR Reading
At 01:30 PM 1/24/2011, you wrote:
>
>Bob,
>
>Many thanks for your quick and detailed response. However, your
>response had three "Emacs!" in it that appear to refer to graphics
>that I can't view. I searched the AeroElectric lists archives and
>the most detailed message re "Emacs!" was yours dated July 31,
>2009. I couldn't find any other relevant messages on how to view
>your graphics/photos.
>
>I'm using a Macbook with OS 10.4.6 (Snow Leopard) that also has a
>full install of Windows XP in it. I opened your reply in three
>different browsers -- Safari, Firefox and Internet Explorer 8 but no joy.
>
>Any thoughts on how I can retrieve/view your "Emacs!" graphical inserts?
scroll down in the archival postings to see
if the images are down there.
I've revisited some references and filtered my
test values through the credibility filter.
The jury is still out. I'd forgotten that
the raw quarter-wave over a good ground plane
should have a resistive component on the order
of 37 ohms at resonance, not 12 ohms. I need
to resolve the discrepancy.
I think I mentioned in another post that the
CI-122 antenna is called out as anything from
1.5:1 (best match?) to 3:1 (not to exceed)
and some numbers in between depending on who's
advertisements you're reading.
I'm not finished unpacking my electro-whizzies
and don't know where my Model 43 meter is. I
seem to recall having a high sensitivity slug
for it that I could drive with a 100 mW unit
oscillator. It will be a couple of weeks
but I'm going to revisit the experiment. I'll
also conduct a calibration procedure on the
MFJ-259 to make sure it hasn't wandered off
into the weeds.
Another Lister cited a marked difference
bewteen on the ground and airborne SWR
readings on a belly mounted antenna. What
would be really cool is to see what your
antenna shows mounted to the center of a
sheet of aluminum on saw horses.
Bob . . .
Bob . . .
________________________________________________________________________________
| Subject: | Re: Comm Antenna & SWR Reading: Additional Info |
| From: | Dj Merrill <deej(at)deej.net> |
On 01/24/2011 03:24 PM, Bob Falstad wrote:
> Is there a rule of thumb in how long to make antenna feed lines for optimum performance?
Typically the longer the cable run, the higher the loss induced by the
cable, so I strive to make the cable runs as short as practical while
still leaving adequate length for maintenance, moving things, etc. An
extra foot or two won't make much difference, but I wouldn't leave an
extra ten feet, for example.
>
> When re-running the tests, would it make any difference to use a more powerful
transmitter than my little hand-held? Or should I stick with what I used originally
to eliminate one more variable that might affect the follow-on data?
I typically test with a 5 watt handheld. I can see no reason to throw
more power at it. However, it might be worth trying the test with a
different handheld to remove the radio itself as a potential source of
the problem.
-Dj
--
Dj Merrill - N1JOV
Glastar Sportsman 2+2 Builder #7118 N421DJ - http://deej.net/sportsman/
Please use Netiquette Guidelines http://tools.ietf.org/html/rfc1855
Kindly TRIM your email replies and post AFTER the relevant text
________________________________________________________________________________
| Subject: | RG-400 Strechable? |
Some time ago while taking the wing off my airplane the RG-400 cable to
the NAV antenna cable took a pretty good pull when the weight of the
wing hung on it.
Question:
While no damage was visible, is it possible to damage the core even
though there was no damage to the external jacket?
Thanks,
Glenn
________________________________________________________________________________
| From: | "William Slaughter" <william_slaughter(at)att.net> |
| Subject: | Off topic electric drag racer |
Both US and Russia started out with pencils, and the hazards mentioned are
true. However, Fisher pen developed it on their own nickel, and it ended up
being used by both sides. Search "nasa space pen" at Snopes.com for the
detailed story.
William
-----Original Message-----
From: owner-aeroelectric-list-server(at)matronics.com
[mailto:owner-aeroelectric-list-server(at)matronics.com] On Behalf Of Noel
Loveys
Sent: Monday, January 24, 2011 10:20 AM
Subject: RE: AeroElectric-List: Off topic electric drag racer
Reminds me of the story about the money NASA spent to build a ball point pen
for space... The Russians used a pencil. Now what was not said. The
pencil leaves dust floating around every time it is used The point can break
off and jam equipment and on at least one occasion the pen was disassembled
and used to actually save a mission. On the surface it looked foolish but
in the long run it was money well spent.
Noel
-----Original Message-----
From: owner-aeroelectric-list-server(at)matronics.com
[mailto:owner-aeroelectric-list-server(at)matronics.com] On Behalf Of Robert
Mitchell
Sent: January 24, 2011 12:34 AM
Subject: Re: AeroElectric-List: Off topic electric drag racer
And, don't forget all the free hand me down benefits we get from NASA thru
taxpayer dollars.
Bob Mitchell
Sent from my iPad
On Jan 23, 2011, at 6:39 PM, "Robert L. Nuckolls, III"
wrote:
>
>
>>
>> Bob, I'm a bit surprised you didn't mention the serious work thousands of
amateur radio buffs did on digital controls let alone digital emissions. I
still remember sending full colour photographs around the world through a 1
khz bandwidth.
>
> Yeah, there was a lot of packet work begin done in the late '80s
> and slow-scan tv predates that by 10 years or more. There
> are no doubt thousands of examples of 'leading edge' process
> and technology that laid the groundwork for the future
> of today's product. But we were talking about systems
> and components that provide low risk, useful services in
> the airplane.
>
> Development costs need to be amortized over great
> numbers for them to become insignificant. Little
> airplanes don't represent much of a market! Our
> demonstrated reservoir of successful recipes
> have come from the volume consumer markets.
>
> The SVLA battery has been around commercially
> since 1970 but it wasn't until 1990 that they got a real
> toe holed in OBAM aviation . . . and only then after
> the un-interruptible power supply market bloomed.
>
> When LORAN was still king and a panel mounted GPS was
> prohibitively expensive, I bought a perfectly serviceable
> GPS for airplanes from a Boat US catalog for $200.
>
> I didn't mean to 'slight' any of the guys who
> did it first. But doing if first doesn't immediately
> and directly translate into useful, cost-effective
> product.
>
>
> Bob . . .
>
>
>
>
________________________________________________________________________________
| From: | "Robert L. Nuckolls, III" <nuckolls.bob(at)aeroelectric.com> |
| Subject: | Re: Comm Antenna & SWR Reading: Additional Info |
At 03:24 PM 1/24/2011, you wrote:
Bob, et al,
Here is some additional information:
To Bob's inquiry "It would be interesting to do an ohmmeter test from
center pin on the antenna's connector and ground. If is shows a
'short', I suspect that some sort of matching system is installed.",
my ohmmeter showed a complete open between the center pin and the
shell of the BNC connector on the antenna base.
Okay, that's not a guarantee that there's
no networking components in the base, the
matching system could be capacitively
coupled . . . but interesting info.
2. The antenna base is installed on the exterior surface of the
composite fuselage and the ground plane is on the inside
surface. They are about 7/16" of an inch apart and, as I mentioned
before, electrically bonded by the four stainless machine screws that
mount the antenna to the airplane. I haven't researched whether the
antenna must be mounted directly on the ground plane -- if so, that
will be an issue since some composite surgery will be required that
I'd really rather avoid.
Not necessarily right ON the ground plane but
if your antenna mounting screws put a "crush"
on anything other than metal, their long
term integrity as electrical conductors is
suspect. I think you mentioned 10-32 attach
hardware. I'd fabricate some spacers with 10-32
clearance holes and just shy of structure thickness
for length. The goal is to have the spacers mate
up with the base of the antenna and the lower
surface of the ground plane. The majority of attach
bolt tension goes to maintaining crush on
the spacer. Your looking for PRESSURE on the
ends of the spacers, they don't need to be
real big in diameter, say 3/8"?
Of course the ends of the spacers and the
surfaces they contact should be bright at
bolt-up time. Use washer's under the nuts on
top of the ground plane to get a flattening
of the ground plane to the top of the
spacer. Torque the hardware to 80% of
limits.
3. I didn't see any adjustment on the antenna itself.
And typically, no TSO/DO qualified antenna would
have any adjustments . . .
Based on the responses, it looks like I've got some more
tweaking/testing to do. Specifically:
Re-test the antennas (including the cat's whisker) and their feed
lines separately, and then together after I've got the feed lines cut
to final length and with their final BNC connectors in place.
I have never seen an antenna "go bad" . . . they're just
too simple and quite robust. If they're not obviously
broken, the probability is that it's okay.
Coax feed lines with properly installed connectors are
high probability performers too. Given what we know
of your installation right now, ground plane bonding
offers the most exciting hypothesis for the measurements
you observed.
The RG-400 feed line from the Comm 1 antenna to the Garmin 430W will
be about 10' long. I can vary (i.e., lengthen) that length if it
will help performance. Is there a rule of thumb in how long to make
antenna feed lines for optimum performance?
Short as practical but allow some service loops if it's
necessary to dismount a black box and withdraw it some
distance before you can access connectors. This goes for
other harnesses as well. Don't agonize over an 'extra' foot
or two of coax at either end.
When re-running the tests, would it make any difference to use a more
powerful transmitter than my little hand-held? Or should I stick
with what I used originally to eliminate one more variable that might
affect the follow-on data?
The Bird 43 is the gold-standard for test equipment
we unwashed can afford. Although with a 5w slug,
you ARE way down on the best linearity curve for
the detector diode. More power MIGHT be helpful.
And yes, measure the SWR at the end of the coax
that attaches to your transceiver.
Bob . . .
________________________________________________________________________________
| From: | "Robert L. Nuckolls, III" <nuckolls.bob(at)aeroelectric.com> |
| Subject: | Re: RG-400 Strechable? |
At 04:47 PM 1/24/2011, you wrote:
>Some time ago while taking the wing off my airplane the RG-400 cable
>to the NAV antenna cable took a pretty good pull when the weight of
>the wing hung on it.
>
>Question:
>
>While no damage was visible, is it possible to damage the core even
>though there was no damage to the external jacket?
I don't think so. That whole build up has a pretty
good tensile strength. Probably in the hundreds of
pounds.
Bob . . .
________________________________________________________________________________
| From: | Mike Welch <mdnanwelch7(at)hotmail.com> |
| Subject: | transponder groundplane |
Group=2C
I went ahead and bought one of those TED 2.6" steel rod antennas
for my transponder.
I intended to installed it on the underside of my fuselage (steel frame
with Poly Fiber covering). I do have a piece of 21" X 23" of .050 AL
under the left seat=2C snuggley laying on the fabric=2C and riveted on some
edges.
Would this be a good transponder groundplane? I could very easily
cut a 1/2" circle in the fabric=2C and mount the TED antenna directly
against the aluminum sheet.
Or=2C I could make a copper "X" groundplane=2C from some 1/2" wide
copper tape I have=2C and secure this one to the fabric=2C leaving a clean
1/2" hole in the fabric for the direct mounting of the antenna against
the copper.
If I make the copper X=2C how long should the legs be? 3" long enough?
Thanks=2C
Mike welch
________________________________________________________________________________
| From: | "Dennis Johnson" <pinetownd(at)volcano.net> |
| Subject: | Flush Cutting Cable Ties |
For cutting nylon cable ties, I've had good luck with these cheap flush
cutters from Harbor Freight:
http://www.harborfreight.com/micro-flush-cutter-90708.html
They cut the loose end of a plastic cable tie flush and don't leave a
sharp edge. Buy a few because they are cheap and don't last forever.
But if you don't try to cut anything other than plastic cable ties or
copper wire, they'll last for most of an airplane project.
Dennis
________________________________________________________________________________
| Subject: | Off topic -- Slowing an electric motor |
| From: | "Dan O'Brien" <limadelta(at)gmail.com> |
Just following up on my question last week about slowing a permanent split
capacitor motor for a wind tunnel I built for my son's science project. A
poster indicated that one can slow such motors with a dimmer switch, which
is what I did. Worked great. We were able to measure the drag
coefficients of golf balls with different dimple patterns at different
Reynolds numbers. Cool project. I've attached a compressed picture of the
wind tunnel as one poster requested.
Thanks for the help guys!
Dan O'Brien
________________________________________________________________________________
| From: | "Robert L. Nuckolls, III" <nuckolls.bob(at)aeroelectric.com> |
| Subject: | Re: transponder groundplane |
At 10:20 PM 1/24/2011, you wrote:
>Group,
>
> I went ahead and bought one of those TED 2.6" steel rod antennas
>for my transponder.
>
> I intended to installed it on the underside of my fuselage (steel frame
>with Poly Fiber covering). I do have a piece of 21" X 23" of .050 AL
>under the left seat, snuggley laying on the fabric, and riveted on some
>edges.
> Would this be a good transponder groundplane?
Yes.
Bob . . .
________________________________________________________________________________
| From: | "Jef Vervoort" <jef.vervoortw(at)telenet.be> |
| Subject: | Odyssey PC680 Battery load tests |
Would that mean that that Panasonic battery is also a good choice for
our RV
?
Thanks
Jef 91031 Belgium, almost there.
_____
Van: owner-aeroelectric-list-server(at)matronics.com
[mailto:owner-aeroelectric-list-server(at)matronics.com] Namens Mickey
Coggins
Verzonden: woensdag 19 januari 2011 19:40
Aan: aeroelectric-list(at)matronics.com
Onderwerp: Re: AeroElectric-List: Odyssey PC680 Battery load tests
Hi Bob,
All three batteries were just sitting on a shelf - not connected to
anything. I didn't do any charging to them during these years, which
makes
me wonder if perhaps they are now "damaged". The two Odyssey
batteries
had very low voltages - can't recall exactly, but it was low single
digits,
and they could not trigger a battery contactor. The Panasonic still had
about 12 volts and worked fine. Exact same treatment for all three
batteries.
You mentioned that the battery tender is not meant as a charger. I also
have a "dumb" charger that just dumps in either 2.5 or 5 amps - I forgot
to
check the voltage it puts out. Do you think that this charger would be
better at recovering these batteries than the battery tender?
Thanks,
Mickey
On Tue, Jan 18, 2011 at 23:50, Robert L. Nuckolls, III
wrote:
I used the West Mountain Radio CBA to test some batteries that I had
hoped
to use in my aircraft. =C2 Unfortunately the PC680 batteries have been
laying
around for about 6 years, and had became quite discharged.
What kind of maintenance did you do on the batteries
while stored? The Battery Tender and Battery Minders
are not intended to be 'chargers' so much as 'maintainers'.
When you have 12v batteries on storage, it's a good idea
to clip them all together in parallel and have some
sort of sophisticated maintainer supporting the lot.
I use the Schumacher 1562 or a Battery Tender to
support my test batteries. Some are pushing 7 years
old with better than 80% of new capacity.
I really thought that the Odyssey batteries would hold a charge better
than
a "standard" Panasonic. =C2 Also, the fact that the Panasonic is giving
me
double the capacity is quite surprising.
Were all three stored under the same conditions?
=C2 I have not yet tried my desulfator, but that's my next step. =C2
I've only
tested one of my two Odyssey batteries, going to test the other "soon".
We'll be interested to hear what you discover.
Bob . . .
--
Mickey Coggins
________________________________________________________________________________
| Subject: | Re: Comm Antenna & SWR Reading -- Too High? |
| From: | "tomcostanza" <Tom(at)CostanzaAndAssociates.com> |
Bob,
In a previous life, I was a seat-of-the-pants, self-taught technician. I was told
that the length of the coax didn't affect the SWR. But intuition, and more
importantly, your test clearly shows that it does. Extrapolating from this,
it seems it would be possible to reduce the SWR to near zero by varying the length
of the coax. But would this affect performance? Your response seems to
indicate that SWR is not a defacto predictor of performance. So why bother measuring
it, unless it's to rule out an open or short, for which there are much
easier measuring techniques?
Also, the Comant specs for 2:1/3:1 probably assume an aluminum airplane. Would
the fact that this is installed on a glass plane not make a difference?
Last question: since I started studying antennas and transmission lines as a kid,
it has always seemed like they were more art than science. Can you point me
to some study material that someone with less than a PhD in physics can understand?
As always, thanks for everything.
Tom Costanza
--------
Clear Skies,
Tom Costanza
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=328378#328378
________________________________________________________________________________
| From: | <bakerocb(at)cox.net> |
| Subject: | "Emacs!" in Response |
1/25/2011
Hello Bob Falstad, You wrote (see copied below): "However, your response had
three"Emacs!" in it that appear to refer to graphics that I can't view."
I have the same problem with Bob Nuckolls' postings, but here is a solution
for me:
a) Go to the Matronics forum web site.
http://forums.matronics.com/
b) Click on the aeroelectric list.
http://forums.matronics.com/viewforum.php?f=3
c) Click on the original subject of the email(s) in question. (Comm Antenna
& SWR Reading -- Too High?)
http://forums.matronics.com/viewtopic.php?t=78934
d) Scroll down to the posted email in question and you should be able to see
any attached graphics or photos.
Please let me / us know how this works for you.
'OC' Baker Says: "The best investment we can make is the time and effort to
gather and understand knowledge."
PS to all: Bob, Bob, Who has got the Bob? Or which Bob?
It is pretty important to me (and I am sure many others) to know which Bob
author that they are reading or which Bob is being addressed.
Would all posters please identify in each case by last name which Bob they
are addressing and which Bob is writing by last name in each instance? Many
thanks.
=====================================================================
From: Bob Falstad <bobair(at)me.com>
Subject: AeroElectric-List: Re: "Emacs!" in Response: Was Comm Antenna &
SWR Reading
Bob,
Many thanks for your quick and detailed response. However, your response
had three
"Emacs!" in it that appear to refer to graphics that I can't view. I
searched
the AeroElectric lists archives and the most detailed message re "Emacs!"
was yours dated July 31, 2009. I couldn't find any other relevant messages
on how to view your graphics/photos.
I'm using a Macbook with OS 10.4.6 (Snow Leopard) that also has a full
install
of Windows XP in it. I opened your reply in three different browsers --
Safari,
Firefox and Internet Explorer 8 but no joy.
Any thoughts on how I can retrieve/view your "Emacs!" graphical inserts?
Best regards,
Bob Falstad
________________________________________________________________________________
| From: | Harley <harley(at)AgelessWings.com> |
| Subject: | Re: Flush Cutting Cable Ties |
YEARS ago, when I was still working for a living, I wrapped,
tensioned and cut off thousands of cable ties over the years with
this little gem.
www.tnb.com/fulltilt/pdf/WT1TB.pdf
I still have it, and on finding it and trying it a few minutes
ago, it still works great. Tensions the tie and then with a
quarter turn twist, cuts it low enough that the cut end is
usually not a problem (once you get used to doing it...even the
first time, it leaves only a small twisted tip).
The only problem with it is if you try to put too much tension on
the tie, the gripper will cut the tie off about a half inch long.
You can usually regrip it and then twist.
I was surprised that it is still being sold after over 30 years
since I first got mine!
Here it is at Newark...that's where I got mine from 30 years
ago. I didn't do any further searching and, as usual with
Newark's prices (I dealt with Newark all the time at work because
I had a crush on my local sales rep!), you may get it cheaper
elsewhere.
Harley Dixon
-----------------------------------------------------------------
On 1/24/2011 10:14 PM, Dennis Johnson wrote:
> For cutting nylon cable ties, I've had good luck with these
> cheap flush cutters from Harbor Freight:
> http://www.harborfreight.com/micro-flush-cutter-90708.html
> They cut the loose end of a plastic cable tie flush and don't
> leave a sharp edge. Buy a few because they are cheap and
> don't last forever. But if you don't try to cut anything other
> than plastic cable ties or copper wire, they'll last for most
> of an airplane project.
> Dennis
> *
> *
________________________________________________________________________________
| From: | Jan de Jong <jan_de_jong(at)casema.nl> |
Having educated myself somewhat on 12V starter motors
and having looked at 13 starter motors rated from 0.85kW to 4.2kW in
more or less detail
I am sharing some generalized results:
1. voltage (12V) and power rating (in kW) are the only values on the
nameplate
2. the power rating indicates mechanical output power (torque times rpm)
3. a power rating is determined in a circuit with a certain lead-acid
battery and a fixed resistance,
not with a fixed supply voltage as one might expect;
this an industry protocol:
- 'largest battery allowed for this motor' Bosch says
(the protocol requires a certain minimum voltage drop I suspect)
- battery at 80% charge and at -20 degrees C
- with 1 mOhm in series
a 'performance curve' is produced, and in some cases made public
(fortunately)
4. at stall (rpm=0):
output power is 0,
input power is at maximum, about 2.7 to 3.5 times the rated power
at 5.5 to 7V the stall current (in A) is about half the power rating
(in W)
(the internal motor resistance is 11/power rating to 14/power rating
(in Ohm))
5. at maximum rpm (torque=0):
output power is 0,
input power is at minimum, 0.7 to 1.0 times rated power
at about 12V the idle current (in A) is 6 to 8% of the power rating
(in W)
6. maximum output power (rated power) occurs at half of maximum rpm and
about 45% of stall current
the input power is twice the output power or a little more
7. the normal start sequence of a 1.5kW (1hp) starter motor:
7.1. stall current buildup in a few tens of ms to 750A at 5.5 to 7V
7.2. speedup to maximum output power in several hundreds of ms,
the current drops to 350A at 9 or 10V
7.3. speedup to equilibrium rpm where output power generated meets power
required,
the current drops to a value not much above 100A at 11V, depending
on the load
8. during initial speedup the power required may soon rise faster than
the output power generated,
the motor will then turn in semi-stalled condition at very high
current - bad
causes are: excessive load, battery internal resistance, circuit
resistance
9. battery CA (cranking amps) rating to allow the motor to make its
rated power:
45% of half the power rating (units of A and W respectively)
-> not less than power rating / 5 (this is also a known rule of thumb)
Some starter motor sizes:
Micron: 0.5kW
Rotax 912: 0.6kW (option 0.9kW)
Jabiru: 1.0kW (option Bosch 1.5kW)
Ulpower: 1.1kW
Largest seen: Kelly 2.8kW
Cheers,
Jan de Jong
________________________________________________________________________________
| Subject: | Re: "Emacs!" in Response |
| From: | "user9253" <fran4sew(at)banyanol.com> |
I agree with Bakerocb. It seems that pictures have been removed from the daily email digest and replaced with Emacs! If I want to see the pictures, I go to http://forums.matronics.com/viewforum.php?f=3 to view them.
Joe
--------
Joe Gores
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=328404#328404
________________________________________________________________________________
| From: | John Morgensen <john(at)morgensen.com> |
| Subject: | Re: "Emacs!" in Response |
No problem here. I get the individual emails. Is the problem only on the
digest?
John
On 1/25/2011 6:45 AM, user9253 wrote:
> --> AeroElectric-List message posted by: "user9253"
>
> I agree with Bakerocb. It seems that pictures have been removed from the daily email digest and replaced with Emacs! If I want to see the pictures, I go to http://forums.matronics.com/viewforum.php?f=3 to view them.
> Joe
>
> --------
> Joe Gores
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=328404#328404
>
>
________________________________________________________________________________
| From: | "Robert L. Nuckolls, III" <nuckolls.bob(at)aeroelectric.com> |
| Subject: | Odyssey PC680 Battery load tests |
At 03:17 AM 1/25/2011, you wrote:
>Would that mean that that Panasonic battery is also a good choice for our RV ?
>
>Thanks
>Jef 91031 Belgium, almost there.
Check out the various threads and articles
on about batteries at http://aeroelectric.com
using the search feature. Also check out the
chapter on batteries in The AeroElectric
Connection.
Over the years, I've come to understand that
there are few batteries not of good
value . . . it's a sort of get what you pay
for idea . . . pretty fundamental to an
honorable free-market economy.
We've also discovered that the selling price
for any product must include amortization
of promotional costs. This is why many products
(like alkaline cells) are often made by the
same factory to be sold under a variety of
brands but with wide range of pricing for
exactly the same product.
One is certainly justified in being skeptical
of any new kid on the block for a battery of
any brand or price. Without special knowledge
of where that battery is made, for how many
other brands and for how long deprives you
of data useful for the reduction of risk.
Having said that mouth full, understand that
batteries suitable for service in our
airplanes are more influenced by what
our design goals are. MOST airplane drivers
are 'happy' with a battery that cranked
the engine today so he could go flying.
Just like in our cars.
HOWEVER . . . if your design goals include
DEPENDING on a battery for an alternative
SOURCE of power in case of alternator
failure, it's incumbent on you to KNOW
mow much power you NEED to support your
ENDURANCE loads and then CONFIRM that
your battery is capable of that task
before you launch into the HIGHER RISK
environment.
This takes homework on your part along
with knowledge of how to craft and maintain
a failure tolerant system to your design
goals ("I want to be able to fly battery-
only for X.X hours")
You CAN do this with a Hawker, Panasonic,
Yuasa, etc. etc. Success will be based on
your own knowledge of what you expect.
Relying on your hangar mate's assertion
that "Panasonics are fine batteries for
airplanes" is not a substitute for that
knowledge.
If your forecasted dependence on a battery
is for day/vfr/pleasure flying, then
perhaps you can treat the battery like
99% of the light aircraft drivers and
virtually all car drivers treat theirs.
Run it till it gasps and dies. If your
expectations and goals that go beyond
that, you'll have to educate yourself
in the processes that go to meeting those
goals.
If the battery of interest bears a well
established branding, it's likely that
you'll pretty much get your money's worth.
Its a very competitive business. Anyone
who has been at it for 20 years or more
has probably earned their place in the market.
But if the battery is some new product
being offered by a bunch of folks who
marketed donuts and bagels in an earlier
life, then exercise due caution.
Bob . . .
________________________________________________________________________________
| From: | "Robert L. Nuckolls, III" <nuckolls.bob(at)aeroelectric.com> |
| Subject: | Re: Comm Antenna & SWR Reading -- Too High? |
At 06:18 AM 1/25/2011, you wrote:
>
>
>Bob,
>
>In a previous life, I was a seat-of-the-pants, self-taught
>technician. I was told that the length of the coax didn't affect
>the SWR. But intuition, and more importantly, your test clearly
>shows that it does.
Yeah but your teachers were right and so are you.
The length of the coax between signal source and
the load has losses. From a practical perspective,
those losses are not significant in setting performance.
In other words, we pick a coax that has an acceptably
low loss for the system we're building.
In the wild and wooly world of RF and transmission
lines, most investigations are carried out with
transmission lines of very low loss such that while
the number is not zero, it's so small as to be
ignored.
> Extrapolating from this, it seems it would be possible to reduce
> the SWR to near zero by varying the length of the coax.
I think you missed an important point in the data.
Yes, SWR varied with frequency because the load on
the far end of the transmission line waves around
in the frequency spectrum. Adding coax MIGHT make
SWR appear better but only if there are losses in
the coax. Losses reduce the magnitude of energy that
makes it to the far end where it suffers reflection
due to mis-match. The same losses reduce magnitude
of energy reflected back to the observer's instrument
at the input end. Yeah, the SWR 'appears' to improve
while in fact, losses have served only to mask the
truth from an otherwise reliable measurement system.
Check out this tutorial on Smith charts:
http://www.microwaves101.com/encyclopedia/Smithchart.cfm
As a practical matter, while investigating of any generator/
transmission line/load combination the observer can
ignore the effects of losses because the transmission
lines are short (less than 360 electrical degrees
or one wavelength). When you plot the characteristics
for any combination of hardware on the Smith chart, they
form a circle of constant SWR. There's an infinite
number of resistance/reactance values represented
by points on that circle . . . but for any given
frequency, the SWR is constant for any length of
transmission line.
When you investigate a range of frequencies, then
the circle explodes and you can get some really
curious graphic art forms. That's because the
antenna at the far end is optimal at one frequency
only. But an size dummy load at the far end
and SWR is zero only when load matches the line.
When the load does not match the line, you get
SWR circles other than 1:1 but they are still
smooth circles and they do not change magnitude
or shape by adjusting line length.
The data I offered supports this. Yes, SWR did
appear to become lower by adding coax but the
real SWR value for the two conditions were identical.
>But would this affect performance? Your response seems to indicate
>that SWR is not a defacto predictor of performance. So why bother
>measuring it, unless it's to rule out an open or short, for which
>there are much easier measuring techniques?
Yes, it affects performance . . . but probably
not in observable ways. One reader noted that an
SWR value on the order of 6:1 implied loss of
50% of radiated energy. That's a 3db drop of
signal strength at the receiving site. The guy
listening to that signal would be unlikely to
hear any difference. At the same time, we COULD
put 100' of coax on the antenna being investigated.
The SWR would get MUCH BETTER but the power situation
would get worse. Not only is REAL SWR unchanged,
we've added losses to the system that mask real
SWR and further reduce power delivered to the
antenna.
There WAS a time when practitioners of the
arts and sciences of aircraft antennas counseled
cutting coax cables to some specific length to
maximize performance. They cited experiments
with a field strength meter to support their
assertions. You could not argue with their
demonstrated success. You could argue their
lack of understanding of what was going on.
In these cases, SWR values in the system had
to be high. Once a piece of transmission line
becomes mis-matched, it becomes part of the
impedance transformation system that attaches
the power generator (tube or transistor) to
the antenna's feedpoint. By fiddling with the
length of a poorly matched feedline, they were
in effect "tuning" the combination of reactances
that participated in that power transfer.
If they put a dummy load on the antenna end
of the transmission line, length would have
no effect on SWR or the transmitter's ability
to deliver power into that transmission line.
>Also, the Comant specs for 2:1/3:1 probably assume an aluminum
>airplane. Would the fact that this is installed on a glass plane
>not make a difference?
You bet. Not only do we need to satisfy minimal
RF requirements for size and geometry of ground
plane, achieving a good RF bond to that ground
plane is important. He cited a 2' x 3' ground
plane. That's the size I used in my experiment.
While not "ideal" (1/4-wave radius disk), it
was certainly adequate to the task. I would not
expect there to be observable difference in
performance between infinite ground plane, aluminum
structure, or glass structure backed up by
6 square feet of aluminum sheet.
>Last question: since I started studying antennas and transmission
>lines as a kid, it has always seemed like they were more art than
>science. Can you point me to some study material that someone with
>less than a PhD in physics can understand?
They are VERY much science. The experiments
have been repeated many times with great
consistency. There is also an art of making
sure we understand and minimize the conditions
that affect the science. I'm sure that's
what we're dealing with here.
There ARE good reasons why we both got the
measurements reported. The goal is to figure
out their veracity and significance. That's
the art of sifting simple-ideas for answers
that define the results.
>As always, thanks for everything.
You're most welcome . . . and thanks for asking!
Bob . . .
________________________________________________________________________________
| From: | paul wilson <pwmac(at)sisna.com> |
Sure Lots of message for good meters. And the HF $4 unit is great for
checking voltages and continuity.
What about a low cost meter that can be used for low resistance
measurements? No need to go down to less than ~2 ohms. But a 20k
lower scale dosen't do much for my needs and I have to drag out my
ancient VTVM to see the resistance. I sure would be nice to have a
handy VOM that gets some low R values.
Any suggestions?
Like to measure sensors on my truck that are supposed to be 3 ohm.
and the truck is 1000 miles from the VTVM because I only carry the
cheepy VOM and leave the VTVM home. - Sigh.
PaulW
________________________________________________________________________________
| From: | Mike Welch <mdnanwelch7(at)hotmail.com> |
>I sure would be nice to have a
> handy VOM that gets some low R values.
> Any suggestions?
> PaulW
Paul=2C
When this subject came up a couple of months ago=2C I had recommended
the Etek digital VOM=2C model #10709=2C sold at Walmart. It has a good fee
l in
your hands=2C and several extra functions (built-in flashlight=2C temp prob
e=2C etc.)
that make it a GREAT model for the money.
I had one I used in doing the electrics for my house I was building. Som
eone
ruined it by spilling coffee in it. I did like it=2C so I made it a point
of going
back to Walmart and getting another one!
For $21 you simply can't go wrong!
Mike Welch
________________________________________________________________________________
| From: | Marvin Haught <handainc(at)madisoncounty.net> |
| Subject: | Re: VOMs again. . . |
The WalMart stores in our area no longer sell that model - what they've
got in stock is just junk. Since my wasn't working, I took it back to
get it replaced, and they no longer stock it. I'm trying to find
another one now since I've got all the leads and everything.
M. Haught
On 1/25/2011 10:57 AM, Mike Welch wrote:
> >I sure would be nice to have a
> > handy VOM that gets some low R values.
> > Any suggestions?
> > PaulW
>
> Paul,
>
> When this subject came up a couple of months ago, I had recommended
> the Etek digital VOM, model #10709, sold at Walmart. It has a good
> feel in
> your hands, and several extra functions (built-in flashlight, temp
> probe, etc.)
> that make it a GREAT model for the money.
>
> I had one I used in doing the electrics for my house I was
> building. Someone
> ruined it by spilling coffee in it. I did like it, so I made it a
> point of going
> back to Walmart and getting another one!
>
> For $21 you simply can't go wrong!
>
> Mike Welch
> *
>
>
> *
________________________________________________________________________________
| From: | "Noel Loveys" <noelloveys(at)yahoo.ca> |
| Subject: | Comm Antenna & SWR Reading |
To accurately measure VHF frequencies the meter has to have fast acting
diodes. Usually meters designed for HF (under 30 mHz) are not fast enough
gating to accurately read swr for higher frequencies. To be sure take your
meter to someone who has a bird or similar meter and see if the calibration
is close.
A technician at a local phone company or amateur who works on repeaters may
be a good place to start.
Noel
-----Original Message-----
From: owner-aeroelectric-list-server(at)matronics.com
[mailto:owner-aeroelectric-list-server(at)matronics.com] On Behalf Of paul
wilson
Sent: January 24, 2011 3:25 PM
Subject: RE: AeroElectric-List: Comm Antenna & SWR Reading
I am not Bob , but I use a forward/reflected SWR meter. Its a low
cost unit that did not have serious badmouthing from the Ham guys.
MFJ-862 SWR/Wattmeter. It has a 30 and 300w max range setting
PaulW
========
At 08:14 AM 1/24/2011, Noel Loveys wrote:
>
>Bob what did you use to measure the forward and reverse power? A bird or
>just a regular SWR meter?
>
>Noel
________________________________________________________________________________
| From: | "Noel Loveys" <noelloveys(at)yahoo.ca> |
| Subject: | Comm Antenna & SWR Reading: Additional Info |
Another problem with making the feed line much too long is what to do with
the access. If you coil it up you have just made another electrical tuning
circuit. This can be really bad with unshielded zip wire like used in some
stereo systems.
Noel
-----Original Message-----
From: owner-aeroelectric-list-server(at)matronics.com
[mailto:owner-aeroelectric-list-server(at)matronics.com] On Behalf Of Dj
Merrill
Sent: January 24, 2011 5:39 PM
Subject: Re: AeroElectric-List: Comm Antenna & SWR Reading: Additional Info
On 01/24/2011 03:24 PM, Bob Falstad wrote:
> Is there a rule of thumb in how long to make antenna feed lines for
optimum performance?
Typically the longer the cable run, the higher the loss induced by
the
cable, so I strive to make the cable runs as short as practical while
still leaving adequate length for maintenance, moving things, etc. An
extra foot or two won't make much difference, but I wouldn't leave an
extra ten feet, for example.
>
> When re-running the tests, would it make any difference to use a more
powerful transmitter than my little hand-held? Or should I stick with what
I used originally to eliminate one more variable that might affect the
follow-on data?
I typically test with a 5 watt handheld. I can see no reason to
throw
more power at it. However, it might be worth trying the test with a
different handheld to remove the radio itself as a potential source of
the problem.
-Dj
--
Dj Merrill - N1JOV
Glastar Sportsman 2+2 Builder #7118 N421DJ - http://deej.net/sportsman/
Please use Netiquette Guidelines http://tools.ietf.org/html/rfc1855
Kindly TRIM your email replies and post AFTER the relevant text
________________________________________________________________________________
| From: | "Robert L. Nuckolls, III" <nuckolls.bob(at)aeroelectric.com> |
| Subject: | Re: Comm Antenna & SWR Reading -- Too High? |
At 10:07 AM 1/25/2011, you wrote:
>
>
>At 06:18 AM 1/25/2011, you wrote:
>>
>>
>>Bob,
>>
>>In a previous life, I was a seat-of-the-pants, self-taught
>>technician. I was told that the length of the coax didn't affect
>>the SWR. But intuition, and more importantly, your test clearly
>>shows that it does.
>> Extrapolating from this, it seems it would be possible to reduce
>> the SWR to near zero by varying the length of the coax.
Permit me a further expansion on this idea. See:
http://www.antennex.com/preview/New/quarter.htm
Here we are tutored on a a really cool feature
of high SWR in a transmission line. The article
talks about two cases were two low SWR systems,
like a 100 ohm antenna and a 50 ohm coax would
like to be joined. It is the nature of a 1/4 wavelength
of transmission line to do a 'mirror image' of
not-perfect SWR terminations at each end.
In the case cited, putting a piece of 75 ohm
transmission line in series with a 100 ohm
load 'mirrors' that 100 ohms into a 50 ohm
value at the other end. Viola! Hooking your
50 ohm coax to a 100 ohm load would give
you 2:1 SWR. Putting a short section of
hi SWR coax in the gap gives you a nice place
to tie 50 ohm coax and have a good match to
100 ohms at the other end.
This condition optimizes at one and one
frequency only. SWR in the matching stub
is never 1:1 and SWR on the feed-point
end is 50 ohms resistive only at one
frequency.
This is a small insight into what appears
to be experimental success in "lowering the
SWR by fiddling with feed line lengths."
In fact, adjusting the feed line length
only alters the combination of R+X for
the combined feed line and antenna such that
the transmitter works a bit better (stronger
radiated signal). In no way does it go to
"lowering SWR" . . . in fact, just as SWR in
the 1/4-wave matching section is never 1:1,
diddling with feed line length depends
on SWR within the feed line being anything
BUT 1:1.
If it WERE 1:1, length would have no difference.
Something other than 1:1 allows you to slide
out along the line to find to optimize the
combination of R+X for your particular
situation.
Bob . . .
________________________________________________________________________________
| From: | "dlicheri" <triangulumx(at)googlemail.com> |
chaps and fellow aviators,
good day. just joined and here is a brief intro. name is dino, I am uk based and
fly my bird (jabiru sk 2200A 2 seat) out of a farm strip in essex. fly as much
as weather permits. pilot since 1999 ...
here is my question.
I recently aquired a Narco NAV 11 in perfect working condition (just had it tested).
i have checked out vor antenna prices and they are extorsionate. i was wondering
if it is possible to DIY a vor ariel and if there are any web based resources/plan
for making one.
much appreciated and many thanx
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=328454#328454
________________________________________________________________________________
| From: | paul wilson <pwmac(at)sisna.com> |
Mike what was it R scale? Max value?
PW
=======
At 08:57 AM 1/25/2011, Mike Welch wrote:
> >I sure would be nice to have a
> > handy VOM that gets some low R values.
> > Any suggestions?
> > PaulW
>
>Paul,
>
> When this subject came up a couple of months ago, I had recommended
>the Etek digital VOM, model #10709, sold at Walmart. It has a good feel in
>your hands, and several extra functions (built-in flashlight, temp
>probe, etc.)
>that make it a GREAT model for the money.
>
> I had one I used in doing the electrics for my house I was
> building. Someone
>ruined it by spilling coffee in it. I did like it, so I made it a
>point of going
>back to Walmart and getting another one!
>
> For $21 you simply can't go wrong!
>
>Mike Welch
>
________________________________________________________________________________
| From: | "Robert L. Nuckolls, III" <nuckolls.bob(at)aeroelectric.com> |
| Subject: | Re: VOMs again. . . |
At 11:07 AM 1/25/2011, you wrote:
>
>Sure Lots of message for good meters. And the HF $4 unit is great
>for checking voltages and continuity.
>What about a low cost meter that can be used for low resistance
>measurements? No need to go down to less than ~2 ohms. But a 20k
>lower scale dosen't do much for my needs and I have to drag out my
>ancient VTVM to see the resistance. I sure would be nice to have a
>handy VOM that gets some low R values.
>Any suggestions?
Only my brother-in-law would get such a deal as I
have for you. See:
http://tinyurl.com/4l3tuj6
A few years back we were wrestling with some switch
and relay issues on fielded airplanes that required
accurate measurements below 1 ohm. As you've noted,
most multimeters don't have the resolution to tell
you much about low resistances. Further, the resistance
of the test leads become a significant portion of
the total resistance being measured.
I crafted a series of devices cited in the article
above. This paper was published to the HBC field
service community.
Setting up the adapter to generate a 0.1 amp
constant current means that resistance across
the 4-wire test connections has a voltage drop of
of 100 mV/ohm. So a reading of 1 volt indicates
a resistance value of 10 ohms. LM317 needs to
have about 2 volts of head-room so the 3 cell
instrument should not be depended on for
measurements above 20 ohms. The 4-cell
instrument can go up to 35 ohms. Depending
on resolution of your VOM, you can accurately
resolve very small resistance values. For
example, the HF $4 VOM on the 200 mV scale
displays 199.9 millivolts. The instrument
display offers you 1 milliom resolution at
2.0 ohms full scale.
Many small, low cost VOMs don't have 3/4"
spaced banana jacks. You can buy banana
plugs that mount on screws with a spacing
of your choice
Emacs!
http://tinyurl.com/4d465gx
Alternatively, you can build the larger
adapter that stands alone and connects
to your multimeter of choice with appropriate
wiring.
>Like to measure sensors on my truck that are supposed to be 3 ohm.
>and the truck is 1000 miles from the VTVM because I only carry the
>cheepy VOM and leave the VTVM home. - Sigh.
>PaulW
Build one of these critters up. You'll
be glad you did. I made up several and
gave them to guys in the shops.
Bob . . .
________________________________________________________________________________
| From: | "Robert L. Nuckolls, III" <nuckolls.bob(at)aeroelectric.com> |
At 12:54 PM 1/25/2011, you wrote:
>Although I have seen those tools I have never seen one used in
>aviation... Too bad... they work.
Our guys on the line and in experimental flight used
them all the time. They were too bulky for my very compact
'engineers toolbox' so I never owned one . . . the
flush-cutter had to suffice. But it wasn't uncommon
for one of the techs to hand me his tool if he observed
my 'neanderthal' techniques. At least I wasn't chewing them
off with my teeth!
Bob . . .
________________________________________________________________________________
| From: | "Noel Loveys" <noelloveys(at)yahoo.ca> |
| Subject: | "Emacs!" in Response |
Having read this thread from the beginning again I would do a continuity
test for ground from the ground plane back to the grounded case of the
radio. While you are at it do a continuity test for the centre conductor of
the RG400. I've seen similar readings caused by a crack in the centre
conductor of coax.
As for the ground plane assuming your ground bond is good to your aluminium
and the centre conductor is intact you may want to try bonding the aluminium
to the aircraft ground system with a separate wire. I've seen instances
where that had to be done on fibreglass boats.
Noel
-----Original Message-----
From: owner-aeroelectric-list-server(at)matronics.com
[mailto:owner-aeroelectric-list-server(at)matronics.com] On Behalf Of
bakerocb(at)cox.net
Sent: January 25, 2011 9:14 AM
Subject: AeroElectric-List: "Emacs!" in Response
1/25/2011
Hello Bob Falstad, You wrote (see copied below): "However, your response had
three"Emacs!" in it that appear to refer to graphics that I can't view."
I have the same problem with Bob Nuckolls' postings, but here is a solution
for me:
a) Go to the Matronics forum web site.
http://forums.matronics.com/
b) Click on the aeroelectric list.
http://forums.matronics.com/viewforum.php?f=3
c) Click on the original subject of the email(s) in question. (Comm Antenna
& SWR Reading -- Too High?)
http://forums.matronics.com/viewtopic.php?t=78934
d) Scroll down to the posted email in question and you should be able to see
any attached graphics or photos.
Please let me / us know how this works for you.
'OC' Baker Says: "The best investment we can make is the time and effort to
gather and understand knowledge."
PS to all: Bob, Bob, Who has got the Bob? Or which Bob?
It is pretty important to me (and I am sure many others) to know which Bob
author that they are reading or which Bob is being addressed.
Would all posters please identify in each case by last name which Bob they
are addressing and which Bob is writing by last name in each instance? Many
thanks.
=====================================================================
From: Bob Falstad <bobair(at)me.com>
Subject: AeroElectric-List: Re: "Emacs!" in Response: Was Comm Antenna &
SWR Reading
Bob,
Many thanks for your quick and detailed response. However, your response
had three
"Emacs!" in it that appear to refer to graphics that I can't view. I
searched
the AeroElectric lists archives and the most detailed message re "Emacs!"
was yours dated July 31, 2009. I couldn't find any other relevant messages
on how to view your graphics/photos.
I'm using a Macbook with OS 10.4.6 (Snow Leopard) that also has a full
install
of Windows XP in it. I opened your reply in three different browsers --
Safari,
Firefox and Internet Explorer 8 but no joy.
Any thoughts on how I can retrieve/view your "Emacs!" graphical inserts?
Best regards,
Bob Falstad
________________________________________________________________________________
| From: | "Robert L. Nuckolls, III" <nuckolls.bob(at)aeroelectric.com> |
| Subject: | Comm Antenna & SWR Reading |
At 12:38 PM 1/25/2011, you wrote:
>
>To accurately measure VHF frequencies the meter has to have fast acting
>diodes. Usually meters designed for HF (under 30 mHz) are not fast enough
>gating to accurately read swr for higher frequencies. To be sure take your
>meter to someone who has a bird or similar meter and see if the calibration
>is close.
>
>A technician at a local phone company or amateur who works on repeaters may
>be a good place to start.
Certainly the characteristics of detector diodes become
more critical as the frequency goes up. Criticality is
also increased as the magnitude of exciting signal goes
down. We touched on this when questioning whether or not
the .5 watt excitation was going to yield good measurements
on a 5 watt full scale instrument.
The rule of thumb for even the Bird instruments is to
select a signal source and element that produces forward
readings in the upper half of scale travel (greater than
2W on a 5W element).
All of the DIY antenna analyzer projects routinely
call out specialty detector diodes line the 1N5711
(point contact Schottky). It's equally critical
to build the bridge from the right kind of resistors
and very tight geometry. There's a lot of reference
data out there for folks interested in DIY antenna
measurements.
Bob . . .
________________________________________________________________________________
| From: | Mike Welch <mdnanwelch7(at)hotmail.com> |
Hi Paul=2C
20M=2C 2M=2C 200K=2C 20K=2C 2K & 200. Marvin was right about them not be
ing
at Walmart=2C it appears. I did a Walmart online search=2C and they didn't
come up.
I checked on eBay. There are two different sellers. One guy wants $40 + s
h.
The other guy wants $32 total. Walmart sold them at $20-$21=2C but they we
re
quite a deal at that=2C IMO. Here's the cheaper guy's auction=3B
http://cgi.ebay.com/ebaymotors/E-Tek-10709-Professional-Digital-Multimeter-
_W0QQcmdZViewItemQQhashZitem41563d5b42QQitemZ280619735874QQptZMotorsQ5fCarQ
5fTruckQ5fPartsQ5fAccessories
> Date: Tue=2C 25 Jan 2011 11:08:51 -0800
> To: aeroelectric-list(at)matronics.com
> From: pwmac(at)sisna.com
> Subject: RE: AeroElectric-List: VOMs again. . .
>
>
> Mike what was it R scale? Max value?
> PW
________________________________________________________________________________
| From: | Dan Morrow <danfm01(at)butter.toast.net> |
| Subject: | Re: "Emacs!" in Response |
On 01/25/2011 07:11 AM, John Morgensen wrote:
>
>
> No problem here. I get the individual emails. Is the problem only on
> the digest?
>
Enclosures are not posted to the digest lists. Here is an excerpt from
the Matronics FAQ at
www.matronics.com/ftp/Archives/RV-List.FAQ.html
**Limited posting of enclosures such as pictures, documents, and spreadsheets
is supported on the Lists. There are a number of restrictions, and these
are detailed below. Please abide by the rules put forth regarding the
content of enclosures.
These are some of the features and limits of enclosures on the Matronics
lists:
1) Enclosures will only be posted to the Real Time version of the Lists.
2) Enclosures will NOT be included in the Daily Digest version of the Lists.
**
The full FAQ file is too big to quote here.
________________________________________________________________________________
| From: | "Robert L. Nuckolls, III" <nuckolls.bob(at)aeroelectric.com> |
At 02:07 PM 1/25/2011, you wrote:
>
>
>chaps and fellow aviators,
>
>good day. just joined and here is a brief intro. name is dino, I am
>uk based and fly my bird (jabiru sk 2200A 2 seat) out of a farm
>strip in essex. fly as much as weather permits. pilot since 1999 ...
>
>here is my question.
>
>I recently aquired a Narco NAV 11 in perfect working condition (just
>had it tested). i have checked out vor antenna prices and they are
>extorsionate. i was wondering if it is possible to DIY a vor ariel
>and if there are any web based resources/plan for making one.
Sure. Make your own 'cat whiskers' from suitable
steel rod. CB antennas can be salvaged for their
corrosion resistant parts. Fabricate a BALUN as
described
http://www.aeroelectric.com/articles/BALUN/Balun_Fabrication.html
Make an insulating configured to fit to your
airplane . . . usually the top cap of a
vertical fin. Fabricate fittings (silver
soldered to your 26" 'whiskers') to mount
the antenna elements to your fin cap with
about 45 degree sweep-back.
Emacs!
Attach BALUN to interior ends and route coax to your
VOR receiver. The anti-rotation scheme shown above
is perhaps not sufficiently robust. I think I'd silver
solder the whiskers into a 5/16 or 3/8" threaded stud.
Bob . . .
________________________________________________________________________________
| From: | "Robert L. Nuckolls, III" <nuckolls.bob(at)aeroelectric.com> |
| Subject: | "Emacs!" in Response |
>As for the ground plane assuming your ground bond is good to your aluminium
>and the centre conductor is intact you may want to try bonding the aluminium
>to the aircraft ground system with a separate wire.
Wires use to connect RF ground systems to any other ground
system are never useful for controlling antenna system
performance.
Bob . . .
________________________________________________________________________________
| From: | "Robert L. Nuckolls, III" <nuckolls.bob(at)aeroelectric.com> |
| Subject: | Comm Antenna & SWR Reading |
Oops! Re-posted with the proper subject line to keep it
attached to the proper thread.
>As for the ground plane assuming your ground bond is good to your aluminium
>and the centre conductor is intact you may want to try bonding the aluminium
>to the aircraft ground system with a separate wire.
Wires use to connect RF ground systems to any other ground
system are never useful for controlling antenna system
performance.
Bob . . .
________________________________________________________________________________
| From: | Harley <harley(at)AgelessWings.com> |
That's the biggest reason I liked that little T&B unit (WT1-TB) I
directed you to in an earlier message today...it is small, fits
in the palm of your hand and can be used anyplace that you can
get your closed hand and point your finger at.
It worked great in all the tight places in the systems I designed
at Pennwalt. And it cuts the tie off flush with the buckle.
Harley
-----------------------------------------------------------------
> III"
>
> At 12:54 PM 1/25/2011, you wrote:
>> Although I have seen those tools I have never seen one used in
>> aviation... Too bad... they work.
>
> Our guys on the line and in experimental flight used
> them all the time. They were too bulky for my very compact
> 'engineers toolbox' so I never owned one . . . the
> flush-cutter had to suffice. But it wasn't uncommon
> for one of the techs to hand me his tool if he observed
> my 'neanderthal' techniques. At least I wasn't chewing them
> off with my teeth!
>
>
> Bob . . .
>
________________________________________________________________________________
| From: | "Noel Loveys" <noelloveys(at)yahoo.ca> |
I don't like seeing... make that feeling the tie wraps but on occasion I do
use them... whenever I do I use the small side cuts but I always make one
or two passes over the cut end with a piece of reasonably fine grit
sandpaper. So far I have yet to cut myself on a tie wrap that I have
personally installed.
Speaking of which I now have to do the wiring on my 912 installation. After
that controls... Gee its cold outside. Supposed to go up to the green side
of 0C Thursday.
Noel
-----Original Message-----
From: owner-aeroelectric-list-server(at)matronics.com
[mailto:owner-aeroelectric-list-server(at)matronics.com] On Behalf Of Robert L.
Nuckolls, III
Sent: January 25, 2011 2:52 PM
Subject: RE: AeroElectric-List: cable ties
At 12:54 PM 1/25/2011, you wrote:
>Although I have seen those tools I have never seen one used in
>aviation... Too bad... they work.
Our guys on the line and in experimental flight used
them all the time. They were too bulky for my very compact
'engineers toolbox' so I never owned one . . . the
flush-cutter had to suffice. But it wasn't uncommon
for one of the techs to hand me his tool if he observed
my 'neanderthal' techniques. At least I wasn't chewing them
off with my teeth!
Bob . . .
________________________________________________________________________________
| From: | "Noel Loveys" <noelloveys(at)yahoo.ca> |
| Subject: | Comm Antenna & SWR Reading |
Thanks for filling in the gaps Bob. What I was getting at was trying to
remove any errors that may have been caused by the meters.
Noel
-----Original Message-----
From: owner-aeroelectric-list-server(at)matronics.com
[mailto:owner-aeroelectric-list-server(at)matronics.com] On Behalf Of Robert L.
Nuckolls, III
Sent: January 25, 2011 3:09 PM
Subject: RE: AeroElectric-List: Comm Antenna & SWR Reading
At 12:38 PM 1/25/2011, you wrote:
>
>To accurately measure VHF frequencies the meter has to have fast acting
>diodes. Usually meters designed for HF (under 30 mHz) are not fast enough
>gating to accurately read swr for higher frequencies. To be sure take your
>meter to someone who has a bird or similar meter and see if the calibration
>is close.
>
>A technician at a local phone company or amateur who works on repeaters may
>be a good place to start.
Certainly the characteristics of detector diodes become
more critical as the frequency goes up. Criticality is
also increased as the magnitude of exciting signal goes
down. We touched on this when questioning whether or not
the .5 watt excitation was going to yield good measurements
on a 5 watt full scale instrument.
The rule of thumb for even the Bird instruments is to
select a signal source and element that produces forward
readings in the upper half of scale travel (greater than
2W on a 5W element).
All of the DIY antenna analyzer projects routinely
call out specialty detector diodes line the 1N5711
(point contact Schottky). It's equally critical
to build the bridge from the right kind of resistors
and very tight geometry. There's a lot of reference
data out there for folks interested in DIY antenna
measurements.
Bob . . .
________________________________________________________________________________
| From: | "Noel Loveys" <noelloveys(at)yahoo.ca> |
| Subject: | "Emacs!" in Response |
The bond I was referring to would be to the same system. Doing that could
nullify the effects of a bad connection to the braid at the antenna end.
Noel
-----Original Message-----
From: owner-aeroelectric-list-server(at)matronics.com
[mailto:owner-aeroelectric-list-server(at)matronics.com] On Behalf Of Robert L.
Nuckolls, III
Sent: January 25, 2011 3:23 PM
Subject: RE: AeroElectric-List: "Emacs!" in Response
>As for the ground plane assuming your ground bond is good to your aluminium
>and the centre conductor is intact you may want to try bonding the
aluminium
>to the aircraft ground system with a separate wire.
Wires use to connect RF ground systems to any other ground
system are never useful for controlling antenna system
performance.
Bob . . .
________________________________________________________________________________
| From: | "Noel Loveys" <noelloveys(at)yahoo.ca> |
I was once asked if it made any difference to the VOR whether the cats
whiskers were sloping forward or rearward. What's your take? Mine was
simply to follow the directions.. but in homebuilt planes you may have to
write your own directions.
Noel
From: owner-aeroelectric-list-server(at)matronics.com
[mailto:owner-aeroelectric-list-server(at)matronics.com] On Behalf Of Robert L.
Nuckolls, III
Sent: January 25, 2011 3:20 PM
Subject: Re: AeroElectric-List: vor antenna
At 02:07 PM 1/25/2011, you wrote:
chaps and fellow aviators,
good day. just joined and here is a brief intro. name is dino, I am uk based
and fly my bird (jabiru sk 2200A 2 seat) out of a farm strip in essex. fly
as much as weather permits. pilot since 1999 ...
here is my question.
I recently aquired a Narco NAV 11 in perfect working condition (just had it
tested). i have checked out vor antenna prices and they are extorsionate. i
was wondering if it is possible to DIY a vor ariel and if there are any web
based resources/plan for making one.
Sure. Make your own 'cat whiskers' from suitable
steel rod. CB antennas can be salvaged for their
corrosion resistant parts. Fabricate a BALUN as
described
http://www.aeroelectric.com/articles/BALUN/Balun_Fabrication.html
Make an insulating configured to fit to your
airplane . . . usually the top cap of a
vertical fin. Fabricate fittings (silver
soldered to your 26" 'whiskers') to mount
the antenna elements to your fin cap with
about 45 degree sweep-back.
Emacs!
Attach BALUN to interior ends and route coax to your
VOR receiver. The anti-rotation scheme shown above
is perhaps not sufficiently robust. I think I'd silver
solder the whiskers into a 5/16 or 3/8" threaded stud.
Bob . . .
________________________________________________________________________________
| From: | "Robert L. Nuckolls, III" <nuckolls.bob(at)aeroelectric.com> |
| Subject: | Comm Antenna & SWR Reading |
As for the ground plane assuming your ground bond is good to your aluminium
and the centre conductor is intact you may want to try bonding the aluminium
to the aircraft ground system with a separate wire.
Wires use to connect RF ground systems to any other ground
system are never useful for controlling antenna system
performance.
------------
The bond I was referring to would be to the same system. Doing that could
nullify the effects of a bad connection to the braid at the antenna end.
You lost me. This is a composite aircraft with an
aluminum sheet on the inside surface for a ground
plane and approx 7/16" worth of composite structure
between the ground plane and the base of the antenna.
I presume there's a centrally located clearance hole
in the composite material for the coax connector.
He described 4 threaded fasteners holding this 'sandwich'
together.
To be sure, a low resistance (micro-ohms), high integrity
(gas tight) connections between the base and the ground plane
are called for. Having "soft" material in the makeup
of this sandwich is counter productive to achieving that
goal. Hence the suggestion for metallic spacers through
the structure to take the mate-up tension loads in the
screws and provide low-inductance jumpers (4 in parallel)
between the antenna base and the ground plane.
"Ground system" is generally interpreted to mean the DC
power ground. On this aircraft, it may well be a firewall
single point ground with lots of wires returning to it.
In this instance, no potential benefits to be gained
by adding conductors between power ground and anything
associated with this antenna installation.
Bob . . .
________________________________________________________________________________
| From: | "Robert L. Nuckolls, III" <nuckolls.bob(at)aeroelectric.com> |
At 03:52 PM 1/25/2011, you wrote:
>I was once asked if it made any difference to the VOR whether the
>cats whiskers were sloping forward or rearward. What's your
>take? Mine was simply to follow the directions.. but in homebuilt
>planes you may have to write your own directions.
>
>Noel
Good question. I've seen them both ways. Putting any
kind of rake angle on them will have effects on radiation
pattern, feed point impedance and aerodynamics. I suppose
somebody had a reason for selecting one over the other
but I doubt that it had to do with optimization in more
than one of the three areas of investigation. From the
performance perspective, it's almost sure to make no
perceivable difference.
Sometimes things are done just because that's the way
we've been doing it for a long time . . . and nobody
remembers why. Most folks would probably think they look
sexier with a rearward rake . . . and indeed, that may
have been the reason.
Bob . . .
________________________________________________________________________________
| From: | Robert Borger <rlborger(at)mac.com> |
Gents,
My 2... Personally, I like Cobra Cable Ties ( http://cobracabletie.com/ ). They are low profile and the trimmed end is protected when trimmed properly. Ya, they cost a bit more than the cheepo stuff, but I think they are worth it.
Bob Borger
Europa Kit #A221 N914XL, XS Tri-Gear, Intercooled 914, Airmaster C/S Prop
On Jan 25, 2011, at 14:38, Noel Loveys wrote:
>
> I don't like seeing... make that feeling the tie wraps but on occasion I do
> use them... whenever I do I use the small side cuts but I always make one
> or two passes over the cut end with a piece of reasonably fine grit
> sandpaper. So far I have yet to cut myself on a tie wrap that I have
> personally installed.
>
> Speaking of which I now have to do the wiring on my 912 installation. After
> that controls... Gee its cold outside. Supposed to go up to the green side
> of 0C Thursday.
>
> Noel
________________________________________________________________________________
| From: | Jared Yates <email(at)jaredyates.com> |
On an airplane with conventional landing gear, you might want to consider
walkaround safety in your forward/aft decision. I had a friend with an old
Piper and he just about poked his eye out one time on a set that was bent
forward.
On Tue, Jan 25, 2011 at 3:07 PM, Robert L. Nuckolls, III <
nuckolls.bob(at)aeroelectric.com> wrote:
> nuckolls.bob(at)aeroelectric.com>
>
> At 03:52 PM 1/25/2011, you wrote:
>
>> I was once asked if it made any difference to the VOR whether the cats
>> whiskers were sloping forward or rearward. What's your take? Mine was
>> simply to follow the directions.. but in homebuilt planes you may have to
>> write your own directions.
>>
>> Noel
>>
>
> Good question. I've seen them both ways. Putting any
> kind of rake angle on them will have effects on radiation
> pattern, feed point impedance and aerodynamics. I suppose
> somebody had a reason for selecting one over the other
> but I doubt that it had to do with optimization in more
> than one of the three areas of investigation. From the
> performance perspective, it's almost sure to make no
> perceivable difference.
>
> Sometimes things are done just because that's the way
> we've been doing it for a long time . . . and nobody
> remembers why. Most folks would probably think they look
> sexier with a rearward rake . . . and indeed, that may
> have been the reason.
>
>
> Bob . . .
>
>
________________________________________________________________________________
| From: | "Robert L. Nuckolls, III" <nuckolls.bob(at)aeroelectric.com> |
| Subject: | Re: VOMs again. . . |
At 11:07 AM 1/25/2011, you wrote:
>
>Sure Lots of message for good meters. And the HF $4 unit is great
>for checking voltages and continuity.
>What about a low cost meter that can be used for low resistance
>measurements? No need to go down to less than ~2 ohms. But a 20k
>lower scale dosen't do much for my needs and I have to drag out my
>ancient VTVM to see the resistance. I sure would be nice to have a
>handy VOM that gets some low R values.
>Any suggestions?
Only my brother-in-law would get such a deal as I
have for you. See:
http://tinyurl.com/4l3tuj6
A few years back we were wrestling with some switch
and relay issues on fielded airplanes that required
accurate measurements below 1 ohm. As you've noted,
most multimeters don't have the resolution to tell
you much about low resistances. Further, the resistance
of the test leads become a significant portion of
the total resistance being measured.
I crafted a series of devices cited in the article
above. This paper was published to the HBC field
service community.
Setting up the adapter to generate a 0.1 amp
constant current means that resistance across
the 4-wire test connections has a voltage drop of
of 100 mV/ohm. So a reading of 1 volt indicates
a resistance value of 10 ohms. LM317 needs to
have about 2 volts of head-room so the 3 cell
instrument should not be depended on for
measurements above 20 ohms. The 4-cell
instrument can go up to 35 ohms. Depending
on resolution of your VOM, you can accurately
resolve very small resistance values. For
example, the HF $4 VOM on the 200 mV scale
displays 199.9 millivolts. The instrument
display offers you 1 milliom resolution at
2.0 ohms full scale.
Many small, low cost VOMs don't have 3/4"
spaced banana jacks. You can buy banana
plugs that mount on screws with a spacing
of your choice
Emacs!
http://tinyurl.com/4d465gx
Alternatively, you can build the larger
adapter that stands alone and connects
to your multimeter of choice with appropriate
wiring.
>Like to measure sensors on my truck that are supposed to be 3 ohm.
>and the truck is 1000 miles from the VTVM because I only carry the
>cheepy VOM and leave the VTVM home. - Sigh.
>PaulW
Build one of these critters up. You'll
be glad you did. I made up several and
gave them to guys in the shops.
Bob . . .
________________________________________________________________________________
| From: | paul wilson <pwmac(at)sisna.com> |
| Subject: | Re: VOMs again. . . |
Bob, I remember this article well, which is why I asked if something
is out there to buy. I seriously doubt a succesful build of your
device considering my abilities.
Maybe you would consider a new product to sell us or even a kit?
Thanks, PaulW
========
At 10:14 AM 1/25/2011, you wrote:
>At 11:07 AM 1/25/2011, you wrote:
>>
>>Sure Lots of message for good meters. And the HF $4 unit is great
>>for checking voltages and continuity.
>>What about a low cost meter that can be used for low resistance
>>measurements? No need to go down to less than ~2 ohms. But a 20k
>>lower scale dosen't do much for my needs and I have to drag out my
>>ancient VTVM to see the resistance. I sure would be nice to have a
>>handy VOM that gets some low R values.
>>Any suggestions?
>
> Only my brother-in-law would get such a deal as I
> have for you. See:
>
>http://tinyurl.com/4l3tuj6
>
> A few years back we were wrestling with some switch
> and relay issues on fielded airplanes that required
> accurate measurements below 1 ohm. As you've noted,
> most multimeters don't have the resolution to tell
> you much about low resistances. Further, the resistance
> of the test leads become a significant portion of
> the total resistance being measured.
>
> I crafted a series of devices cited in the article
> above. This paper was published to the HBC field
> service community.
>
> Setting up the adapter to generate a 0.1 amp
> constant current means that resistance across
> the 4-wire test connections has a voltage drop of
> of 100 mV/ohm. So a reading of 1 volt indicates
> a resistance value of 10 ohms. LM317 needs to
> have about 2 volts of head-room so the 3 cell
> instrument should not be depended on for
> measurements above 20 ohms. The 4-cell
> instrument can go up to 35 ohms. Depending
> on resolution of your VOM, you can accurately
> resolve very small resistance values. For
> example, the HF $4 VOM on the 200 mV scale
> displays 199.9 millivolts. The instrument
> display offers you 1 milliom resolution at
> 2.0 ohms full scale.
>
> Many small, low cost VOMs don't have 3/4"
> spaced banana jacks. You can buy banana
> plugs that mount on screws with a spacing
> of your choice
>
>Emacs!
>
>
>http://tinyurl.com/4d465gx
>
> Alternatively, you can build the larger
> adapter that stands alone and connects
> to your multimeter of choice with appropriate
> wiring.
>
>
>>Like to measure sensors on my truck that are supposed to be 3 ohm.
>>and the truck is 1000 miles from the VTVM because I only carry the
>>cheepy VOM and leave the VTVM home. - Sigh.
>>PaulW
>
> Build one of these critters up. You'll
> be glad you did. I made up several and
> gave them to guys in the shops.
>
>
> Bob . . .
________________________________________________________________________________
| From: | "Robert L. Nuckolls, III" <nuckolls.bob(at)aeroelectric.com> |
| Subject: | Low resistance measurement adapter. |
At 05:37 PM 1/25/2011, you wrote:
>Bob, I remember this article well, which is why I asked if something
>is out there to buy. I seriously doubt a succesful build of your
>device considering my abilities.
Nobody in your local acquaintance that could
help you?
>Maybe you would consider a new product to sell us or even a kit?
Hmmm . . . possibly a product. "Kits" tend to be more expensive
to gin-up and sell than completed products. I think something
like this would sell for $35 to $40. It would be interesting
to know if other folks on the List have an interest in having this
class of measurement capability.
Maybe I could do a one-of-a-kind. It would take about
30 minutes to built one.
Bob . . .
________________________________________________________________________________
| Subject: | Re: Low resistance measurement adapter. |
| From: | Robert Borger <rlborger(at)mac.com> |
Bob,
I'd be interested.
Bob Borger
3705 Lynchburg Dr.
Corinth, TX 76208
Home: 940-497-2123
Cel: 817-992-1117
On Jan 25, 2011, at 18:18, Robert L. Nuckolls, III wrote:
>
> At 05:37 PM 1/25/2011, you wrote:
>> Bob, I remember this article well, which is why I asked if something is out
there to buy. I seriously doubt a succesful build of your device considering my
abilities.
>
> Nobody in your local acquaintance that could
> help you?
>
>> Maybe you would consider a new product to sell us or even a kit?
>
> Hmmm . . . possibly a product. "Kits" tend to be more expensive
> to gin-up and sell than completed products. I think something
> like this would sell for $35 to $40. It would be interesting
> to know if other folks on the List have an interest in having this
> class of measurement capability.
>
> Maybe I could do a one-of-a-kind. It would take about
> 30 minutes to built one.
>
>
> Bob . . .
________________________________________________________________________________
| From: | "Noel Loveys" <noelloveys(at)yahoo.ca> |
| Subject: | Comm Antenna & SWR Reading |
Bob:
I think we are talking about slightly different things here.
I suspect there is no direct connection between the braid of the coax
(ground) and the ground plane. Most of these antennas are designed to be
mounted on aluminium skins. I am thinking that the ground plane is totally
afloat and not connected in any way to the braid. Of course this is easy to
check by simply ringing between the ground plane and the exterior of the
BNC.
Noel
-----Original Message-----
From: owner-aeroelectric-list-server(at)matronics.com
[mailto:owner-aeroelectric-list-server(at)matronics.com] On Behalf Of Robert L.
Nuckolls, III
Sent: January 25, 2011 4:31 PM
Subject: RE: AeroElectric-List: Comm Antenna & SWR Reading
As for the ground plane assuming your ground bond is good to your aluminium
and the centre conductor is intact you may want to try bonding the aluminium
to the aircraft ground system with a separate wire.
Wires use to connect RF ground systems to any other ground
system are never useful for controlling antenna system
performance.
------------
The bond I was referring to would be to the same system. Doing that could
nullify the effects of a bad connection to the braid at the antenna end.
You lost me. This is a composite aircraft with an
aluminum sheet on the inside surface for a ground
plane and approx 7/16" worth of composite structure
between the ground plane and the base of the antenna.
I presume there's a centrally located clearance hole
in the composite material for the coax connector.
He described 4 threaded fasteners holding this 'sandwich'
together.
To be sure, a low resistance (micro-ohms), high integrity
(gas tight) connections between the base and the ground plane
are called for. Having "soft" material in the makeup
of this sandwich is counter productive to achieving that
goal. Hence the suggestion for metallic spacers through
the structure to take the mate-up tension loads in the
screws and provide low-inductance jumpers (4 in parallel)
between the antenna base and the ground plane.
"Ground system" is generally interpreted to mean the DC
power ground. On this aircraft, it may well be a firewall
single point ground with lots of wires returning to it.
In this instance, no potential benefits to be gained
by adding conductors between power ground and anything
associated with this antenna installation.
Bob . . .
________________________________________________________________________________
| From: | "Noel Loveys" <noelloveys(at)yahoo.ca> |
Several early Pipers and Cessnas had the VOR antennas pointed forward. That
is the way the Maintenance Manual required they be installed. I suppose to
legally turn them around would require an STC.
Noel
From: owner-aeroelectric-list-server(at)matronics.com
[mailto:owner-aeroelectric-list-server(at)matronics.com] On Behalf Of Jared
Yates
Sent: January 25, 2011 6:16 PM
Subject: Re: AeroElectric-List: vor antenna
On an airplane with conventional landing gear, you might want to consider
walkaround safety in your forward/aft decision. I had a friend with an old
Piper and he just about poked his eye out one time on a set that was bent
forward.
On Tue, Jan 25, 2011 at 3:07 PM, Robert L. Nuckolls, III
wrote:
At 03:52 PM 1/25/2011, you wrote:
I was once asked if it made any difference to the VOR whether the cats
whiskers were sloping forward or rearward. What's your take? Mine was
simply to follow the directions.. but in homebuilt planes you may have to
write your own directions.
Noel
Good question. I've seen them both ways. Putting any
kind of rake angle on them will have effects on radiation
pattern, feed point impedance and aerodynamics. I suppose
somebody had a reason for selecting one over the other
but I doubt that it had to do with optimization in more
than one of the three areas of investigation. From the
performance perspective, it's almost sure to make no
perceivable difference.
Sometimes things are done just because that's the way
we've been doing it for a long time . . . and nobody
remembers why. Most folks would probably think they look
sexier with a rearward rake . . . and indeed, that may
have been the reason.
Bob . . .
,
www.matronics.com/Navigator?AeroElectric-List"
target="_blank">http://www.matronics.com/Navigator?AeroElectric-List
ronics.com/" target="_blank">http://forums.matronics.com
Matt Dralle, List Admin.
====
________________________________________________________________________________
| From: | BobsV35B(at)aol.com |
Good Morning Noel,
I am sure you can get as many opinions as there are mechanics holding an
IA, but I would just make log book entry which can be done by anyone holding
an Airframe mechanic certificate. Strictly a Minor alteration in my opinion.
Happy Skies,
Old Bob
A&P/IA
Downers Grove, IL
In a message dated 1/25/2011 10:15:30 P.M. Central Standard Time,
noelloveys(at)yahoo.ca writes:
Several early Pipers and Cessnas had the VOR antennas pointed forward.
That is the way the Maintenance Manual required they be installed. I suppose
to legally turn them around would require an STC.
Noel
From: owner-aeroelectric-list-server(at)matronics.com
[mailto:owner-aeroelectric-list-server(at)matronics.com] On Behalf Of Jared Yates
Sent: January 25, 2011 6:16 PM
Subject: Re: AeroElectric-List: vor antenna
On an airplane with conventional landing gear, you might want to consider
walkaround safety in your forward/aft decision. I had a friend with an old
Piper and he just about poked his eye out one time on a set that was bent
forward.
On Tue, Jan 25, 2011 at 3:07 PM, Robert L. Nuckolls, III
<_nuckolls.bob(at)aeroelectric.com_ (mailto:nuckolls.bob(at)aeroelectric.com) > wrote:
<_nuckolls.bob(at)aeroelectric.com_ (mailto:nuckolls.bob(at)aeroelectric.com) >
At 03:52 PM 1/25/2011, you wrote:
I was once asked if it made any difference to the VOR whether the cats
whiskers were sloping forward or rearward. What's your take? Mine was simply
to follow the directions.. but in homebuilt planes you may have to write
your own directions.
Noel
Good question. I've seen them both ways. Putting any
kind of rake angle on them will have effects on radiation
pattern, feed point impedance and aerodynamics. I suppose
somebody had a reason for selecting one over the other
but I doubt that it had to do with optimization in more
than one of the three areas of investigation. From the
performance perspective, it's almost sure to make no
perceivable difference.
Sometimes things are done just because that's the way
we've been doing it for a long time . . . and nobody
remembers why. Most folks would probably think they look
sexier with a rearward rake . . . and indeed, that may
have been the reason.
Bob . . .
,
www.matronics.com/Navigator?AeroElectric-List"
target="_blank">http://www.matronics.com/Navigator?AeroElectric-List
ronics.com/" target="_blank">http://forums.matronics.com
Matt Dralle, List Admin.
====
http://www.matronics.com/Navigator?AeroElectric-List
http://forums.matronics.com
http://www.matronics.com/contribution
(http://www.matronics.com/Navigator?AeroElectric-List)
(http://www.matronics.com/contribution)
________________________________________________________________________________
| From: | "Noel Loveys" <noelloveys(at)yahoo.ca> |
Practically speaking I would just call the TC (Transport Canada) inspector
and ask him about it. They can get uppity about things like that. But
considering the speed of the aircraft he would probably authorize an entry.
In the log entry I would also mention the discussion with the TC inspector.
If the inspector was having a bad day he would insist on following the MM.
Noel
From: owner-aeroelectric-list-server(at)matronics.com
[mailto:owner-aeroelectric-list-server(at)matronics.com] On Behalf Of
BobsV35B(at)aol.com
Sent: January 26, 2011 8:26 AM
Subject: Re: AeroElectric-List: vor antenna
Good Morning Noel,
I am sure you can get as many opinions as there are mechanics holding an IA,
but I would just make log book entry which can be done by anyone holding an
Airframe mechanic certificate. Strictly a Minor alteration in my opinion.
Happy Skies,
Old Bob
A&P/IA
Downers Grove, IL
In a message dated 1/25/2011 10:15:30 P.M. Central Standard Time,
noelloveys(at)yahoo.ca writes:
Several early Pipers and Cessnas had the VOR antennas pointed forward. That
is the way the Maintenance Manual required they be installed. I suppose to
legally turn them around would require an STC.
Noel
From: owner-aeroelectric-list-server(at)matronics.com
[mailto:owner-aeroelectric-list-server(at)matronics.com] On Behalf Of Jared
Yates
Sent: January 25, 2011 6:16 PM
Subject: Re: AeroElectric-List: vor antenna
On an airplane with conventional landing gear, you might want to consider
walkaround safety in your forward/aft decision. I had a friend with an old
Piper and he just about poked his eye out one time on a set that was bent
forward.
On Tue, Jan 25, 2011 at 3:07 PM, Robert L. Nuckolls, III
wrote:
At 03:52 PM 1/25/2011, you wrote:
I was once asked if it made any difference to the VOR whether the cats
whiskers were sloping forward or rearward. What's your take? Mine was
simply to follow the directions.. but in homebuilt planes you may have to
write your own directions.
Noel
Good question. I've seen them both ways. Putting any
kind of rake angle on them will have effects on radiation
pattern, feed point impedance and aerodynamics. I suppose
somebody had a reason for selecting one over the other
but I doubt that it had to do with optimization in more
than one of the three areas of investigation. From the
performance perspective, it's almost sure to make no
perceivable difference.
Sometimes things are done just because that's the way
we've been doing it for a long time . . . and nobody
remembers why. Most folks would probably think they look
sexier with a rearward rake . . . and indeed, that may
have been the reason.
Bob . . .
,
www.matronics.com/Navigator?AeroElectric-List"
target="_blank">http://www.matronics.com/Navigator?AeroElectric-List
ronics.com/" target="_blank">http://forums.matronics.com
Matt Dralle, List Admin.
====
http://www.matronics.com/Navigator?AeroElectric-List
http://forums.matronics.com
http://www.matronics.com/contribution
===================================
List
href="http://www.matronics.com/Navigator?AeroElectric-List">http://www.matro
nics.com/Navigator?AeroElectric-List
===================================
ms.matronics.com/">http://forums.matronics.com
===================================
tp://www.matronics.com/contribution">http://www.matronics.com/contribution
===================================
________________________________________________________________________________
| From: | paul wilson <pwmac(at)sisna.com> |
| Subject: | Re: Low resistance measurement adapter. |
I would buy one from you before tackaling a build myself. Sign me up for one..
PaulW
========
At 04:18 PM 1/25/2011, you wrote:
>
>
>At 05:37 PM 1/25/2011, you wrote:
>>Bob, I remember this article well, which is why I asked if
>>something is out there to buy. I seriously doubt a succesful build
>>of your device considering my abilities.
>
> Nobody in your local acquaintance that could
> help you?
>
>>Maybe you would consider a new product to sell us or even a kit?
>
> Hmmm . . . possibly a product. "Kits" tend to be more expensive
> to gin-up and sell than completed products. I think something
> like this would sell for $35 to $40. It would be interesting
> to know if other folks on the List have an interest in having this
> class of measurement capability.
>
> Maybe I could do a one-of-a-kind. It would take about
> 30 minutes to built one.
>
>
> Bob . . .
>
>
________________________________________________________________________________
| From: | "Robert L. Nuckolls, III" <nuckolls.bob(at)aeroelectric.com> |
| Subject: | Comm Antenna & SWR Reading |
At 10:51 PM 1/25/2011, you wrote:
>
>Bob:
>
>I think we are talking about slightly different things here.
>
>I suspect there is no direct connection between the braid of the coax
>(ground) and the ground plane. Most of these antennas are designed to be
>mounted on aluminium skins. I am thinking that the ground plane is totally
>afloat and not connected in any way to the braid. Of course this is easy to
>check by simply ringing between the ground plane and the exterior of the
>BNC.
The braid MUST come to a very low impedance connection
to the ground plane else the coax becomes 'un-terminated'.
In fact, the high SWR readings Bob cited may have been
the result of poor contact between the antenna base
and the ground plane.
The ideal ground plane behaves as an infinite number of
elements that might otherwise be a center fed dipole
oriented in a plane at right angles to the antenna.
Consider the dipole with coax center conductor to one
element, shield to the other. Yeah, balanced antenna
and unbalanced feedline . . . not the best we know how
to do.
Now bend the shield-side element 90 degrees to center-
conductor element. Very lopsided and not quite so balanced
antenna . . . with the 'bent' element NOT contributing to
a useful radiation pattern. Start adding elements on
the shield side. Once you get to 4 elements, 90 degrees
apart, the current in each element is 1/16th and you have
4 resonant elements in parallel giving 1/4th feedpoint
impedance compared to a single element. Tendency of the
'radials' to radiate is much suppressed and the lion's
share of energy is conducted to the center-conductor element.
Now increase the number of radials to 1 bazillion and
you have a solid surface, not unlike the skin of an
airplane . . . or the sheet of aluminum inside the
composite shell of Bob's airplane.
But for the antenna to perform at its best, the
ideal radiation resistance of the ground plane
is zero (lots in parallel). Further, the electrical
connection from shield ground to ground
plane is as close to zero ohms as we can
make it.
Bob . . .
________________________________________________________________________________
| From: | "Robert L. Nuckolls, III" <nuckolls.bob(at)aeroelectric.com> |
| Subject: | Re: Low resistance measurement adapter. |
At 10:27 AM 1/26/2011, you wrote:
>
>I would buy one from you before tackaling a build myself. Sign me up for one..
>PaulW
Okay. I've figured out a way to package one
with a minimum of time. I'll need to order
some parts. The AEC9008-1 Low Ohms Test Adapter has
been added to the catalog at:
https://matronics.com/aeroelectric/Catalog/AECcatalog.html
Interested individuals can place orders there.
Bob . . .
________________________________________________________________________________
| From: | "Noel Loveys" <noelloveys(at)yahoo.ca> |
| Subject: | Comm Antenna & SWR Reading |
Now... I think I'm on your page!
Most of the fancy high speed antennae I've seen have been made specifically
made to mount on metal planes. Antennae for composite planes generally have
the ground plane built in to them. The base of the antenna makes the
connection for the ground plane while the mounting screws are simply that, a
method to physically mount the antenna to the plane.... not necessarily to
provide a path for the ground plane.
BTW I do admire your explanations.
Noel
The braid MUST come to a very low impedance connection
to the ground plane else the coax becomes 'un-terminated'.
In fact, the high SWR readings Bob cited may have been
the result of poor contact between the antenna base
and the ground plane.
The ideal ground plane behaves as an infinite number of
elements that might otherwise be a center fed dipole
oriented in a plane at right angles to the antenna.
Consider the dipole with coax center conductor to one
element, shield to the other. Yeah, balanced antenna
and unbalanced feedline . . . not the best we know how
to do.
Now bend the shield-side element 90 degrees to center-
conductor element. Very lopsided and not quite so balanced
antenna . . . with the 'bent' element NOT contributing to
a useful radiation pattern. Start adding elements on
the shield side. Once you get to 4 elements, 90 degrees
apart, the current in each element is 1/16th and you have
4 resonant elements in parallel giving 1/4th feedpoint
impedance compared to a single element. Tendency of the
'radials' to radiate is much suppressed and the lion's
share of energy is conducted to the center-conductor element.
Now increase the number of radials to 1 bazillion and
you have a solid surface, not unlike the skin of an
airplane . . . or the sheet of aluminum inside the
composite shell of Bob's airplane.
But for the antenna to perform at its best, the
ideal radiation resistance of the ground plane
is zero (lots in parallel). Further, the electrical
connection from shield ground to ground
plane is as close to zero ohms as we can
make it.
Bob . . .
________________________________________________________________________________
| From: | Bob Falstad <bobair(at)me.com> |
| Subject: | Comm Antenna & SWR: More Information |
Bob N., et al,
I've been doing some reading re my antenna issue and here's what I've
found so far (in no particular order).
Cobham/Comant has some good information on installing their antennas.
See
Installation Guides (including PDF of AC43.13-2B):
http://www.cobham.com/about-cobham/avionics-and-surveillance/about-us/satc
om/fullerton/installation-guide.aspx
FAQs
http://www.cobham.com/about-cobham/avionics-and-surveillance/about-us/satc
om/fullerton/faqs.aspx
Data Sheet for the subject Comm Antenna that I'm using (Comant
CI-122)
http://www.cobham.com/media/9104/ci%20122%20data%20sheet.pdf
Cobham/Comant's installation instructions follow AC43.13-2B fairly
closely and, in fact, refer to that FAA Advisory Circular in several
places.
Additional detail about my ground plane installation.
My ground plane isn't symmetrical (and, contrary to my earlier post, it
is actually 24" x 34", not 24" x 36" -- I had cut 2" off the length so
that it would fit in the space I had available). I also didn't mention
that I cut two slots in the ground plane so that it would fit over a
couple of supports for the floors in my baggage compartment. These
slots are ~3" x 1/2" and are about 10" aft of the antenna base and about
4" either side of the fuselage centerline. Will these slots in the
ground plane degrade the ground plane's performance?
The ground plane is also primed with "rattle-can" self-etching primer.
But as Bob N. supposed, I do have an access hole in the ground plane for
the antenna BNC connector centered among the four 10-32 stainless
machine screws in the antenna base. I used a washer stack to get as
close as possible to the cored composite shell thickness and the
hardware is clamped on the antenna base, through the non-cored
fiberglass exterior skin, the washer stack and the ground plane. The
ground plane metal is "bright" under the washers. Cobham/Comant
endorses this approach (see FAQ #6 at
http://www.cobham.com/about-cobham/avionics-and-surveillance/about-us/satc
om/fullerton/faqs.aspx#171).
Cobham/Comant says the resistance between the ground plane and the
antenna connector should be 3 milliohms (see
http://www.cobham.com/media/5051/compositeaircraftinstallation.pdf). My
ohmmeter only reads to 0.1 Ohm and I can't measure lower than that
without making up one of Bob N's four-wire ohmmeters.
Antenna choice, revisit?
Cobham/Comant isn't very positive about bent whip antennas for Comm 1.
They say "Bent whips may not provide the best VSWR because of proximity
to the ground plane (aircraft skin), which can cause reflections, plus
they lack overall height. Remember, VHF antennas =93like=94 to be tall
and straight for best operation." See FAQ #2.
Other than the antenna selection issue itself, this reading leads me to
three additional areas to investigate: ground plane symmetry, ground
plane size, and antenna mounting location on ground plane.
Re ground plane symmetry...
AC43.13-2B, paragraph 310(b) on page 27 says that "...ground plane
symmetry is critical." There is no reason or engineering data given but
its a fairly direct statement. After re-running the tests with my 24" x
34" practice ground plane, I may cut it back to 24" x 24" to see what
VSWR readings I get with that size.
Re ground plane size...
I understand that, in theory, the ideal ground plane is of infinite
dimension. (For an aside, see quote below.) Bob N. says the practical
ideal is a disc with a radius equal to one-quarter of the wavelength.
An on-line calculator told me that the wavelength at 122.95 MHz is 8'.
One fourth of that is 2'. But that means the idealized disc should have
a diameter of 4'. My ground plane is only 24" wide -- half of what it
should be. It isn't feasible to put a ground plane 4' wide in my plane
-- most of it would have to curl up the sides of the fuselage which
would defeat the purpose anyhow. Moreover, AC43.13-2B, paragraph
310(b), page 27, says most antennas require a ground plane size of
approximately 24" x 24".
Re antenna mounting location on ground plane...
In addition to the issue of the symmetry of the ground plane itself,
will it make a difference in VSWR if the antenna base is not mounted in
the center of the ground plane. As I mentioned in my earlier post, I
mounted the base about 1/3 of the distance along the long axis so that
the entire bent whip would be "covered" by the ground plane. But if,
electrically, the bent whip really behaves like the straight piece of 12
AWG wire Bob N. used in his experiment, then that seems to indicate that
the antenna base needs to be installed in the center of the ground
plane, whether the ground plane is square or rectangular.
Next steps...
I'm finishing up the final terminations on my feed lines and will
jury-rig an external ground plane in order to re-do the tests outside
the airplane as Bob N. suggested. I hope to have the new test data to
you in the next couple of days.
Bonus data point re VOR Antenna installation direction...
Cobham/Comant says the dipoles should be pointed forward. See
http://www.cobham.com/about-cobham/avionics-and-surveillance/about-us/satc
om/fullerton/faqs.aspx#171
Do VOR/GS V-Dipoles such as the CI 158C need to be =93pointed=94 forward
or aft ?
For best results, the radiating elements should be directed
forward, as the emitted pattern needs to =93see=94 forward and downward.
However, some aircraft owners believe they provide a better appearance
if the radiators are pointed aft. If mounted in this manner, the
installer should flight check for proper antenna performance.
(I installed my pointing aft because it looks better. Now I'll have to
pay extra attention on the flight check.)
Best regards,
Bob Falstad
GlaStar N248BF
"In theory, there is no difference between theory and practice. In
practice, there is." (I've heard this attributed to various people,
most often Yogi Berra.)
________________________________________________________________________________
| From: | "Keith Burris" <klburris(at)frontiernet.net> |
| Subject: | Re: Low resistance measurement adapter. |
Bob;
Id be interested in the device.
-- Keith
________________________________________________________________________________
| From: | "Robert L. Nuckolls, III" <nuckolls.bob(at)aeroelectric.com> |
| Subject: | Re: Low resistance measurement adapter. |
At 05:20 PM 1/26/2011, you wrote:
>Bob;
>I'd be interested in the device.
I have orders for several. You can join them
at:
https://matronics.com/aeroelectric/Catalog/AECcatalog.html
Bob . . .
________________________________________________________________________________
| From: | Mike Welch <mdnanwelch7(at)hotmail.com> |
| Subject: | coax antenna cable length |
Guys=2C
I have seen it suggested that when cutting off an antenna cable
for your com radio=2C nav radio=2C etc.=2C that you are supposed to cut
the cable at EVEN multiples of one length of a dipole mast.
In the example of a com radio=2C one article states the dipole length
of a com radio to be 20". Therefore=2C you should double this=2C and
use this new length to calculate your final minimum cable length.
Like this=3B dipole = 20"=2C so our increment would be 40". Now=2C
beginning at the back of the radio (not at a junction of a pigtail)=2C
start counting off 40" increments until we have enough cable to
comfortably reach the actual antenna. Meaning=3B only cut the cable at
40"=2C 80"=2C 120"=2C 160"=2C 200"=2C etc.
If=2C after we've done an excellent routing of the cable=2C we find our
antenna is not located at a 40" increment=2C then we should proceed
to the next full length of our 40" increment prior to cutting the cable.
Here's my question=3B I read from a prominent=2C nationally known=2C
avionics guru that this is not all that necessary. If I recall correctly
=2C
he said he has done SWR tests=2C and the cable length (cut off at even
multiples) had little effect on the antennas performance. In other
words=2C it didn't really matter what the cable length was=2C i.e..=2C 180"
or 205"=2C etc.
If I'm a little fuzzy on my facts here=2C it's because this information
is from several years ago. But=2C after all these years=2C I really would
like to now the facts!!
Is it really all that critical what the cut-off measurement is for a coax
cable for aircraft radios?
Thanks=2C Mike Welch
________________________________________________________________________________
| From: | Bob Falstad <bobair(at)me.com> |
| Subject: | Comm Antenna & SWR: Grounding the Ground Plane: Ref: |
Bob N's. Message 27 Posted on 1-25-11
Bob N., et al,
Based on his reading of Figure 3-4 on page 28 of AC43.13-2B, my Ham/EE/PE buddy
asked me to check the resistance between the ground plane and the ground system
in my plane. (And yes, as you correctly surmised, I'm using a B&C "forest
of tabs" on the firewall for my grounding system supplemented with your 37-pin
Dsub ground bus for avionics grounds mounted next to it.)
As expected, there was a complete open between my ground plane and the grounding
system in the airplane. This is consistent with your comments in the message
referenced above.
But when, for example, a comm antenna is mounted on top of the wing on a Cessna,
I presume it is electrically bonded to the wing which acts as the ground plane.
But isn't the wing also part of the ground system for the airplane itself?
With a coax connector attached to the antenna isn't there now two ground paths
from the antenna to the radio chassis in its mounting rack? Does this create
a ground loop and if so, are its effects positive, benign, or negative? Or
is the ground through the coax between the antenna and the radio isolated in
the radio chassis so the loop isn't completed? In thinking about my setup (if
I had an-all metal airplane), it seems like the loop would be completed since
the BNC connector at the radio end of the feed line connects to another BNC
connector that is mounted in the back plane of the radio (Garmin 430W) chassis
and it appears to me that the pass-through BNC connector in the chassis back
plane isn't insulated from the radio chassis itself.
Your thought and comments?
Best regards,
Bob Falstad
GlaStar N248BF
________________________________________________________________________________
| From: | bob noffs <icubob(at)gmail.com> |
hi all,
anyone have any experience with a wire tracer that they can recommend one?
under $ 60 i hope.
bob noffs
________________________________________________________________________________
| From: | "Robert L. Nuckolls, III" <nuckolls.bob(at)aeroelectric.com> |
| Subject: | Re: Comm Antenna & SWR: More Information |
Additional detail about my ground plane installation.
My ground plane isn't symmetrical (and, contrary to my earlier post,
it is actually 24" x 34", not 24" x 36" -- I had cut 2" off the
length so that it would fit in the space I had available). I also
didn't mention that I cut two slots in the ground plane so that it
would fit over a couple of supports for the floors in my baggage
compartment. These slots are ~3" x 1/2" and are about 10" aft of the
antenna base and about 4" either side of the fuselage
centerline. Will these slots in the ground plane degrade the ground
plane's performance?
Not much . . . if any. Let's consider the way
a ground plane works. In an earlier post I
explained how the sum total of 4 'prefect'
radials routed 80% plus of energy delivered
to the end of the coax to be delivered to
the antenna.
Now, if you draw say 100 equally spaced lines
from the antenna location on your ground plane
out to the edge, we can see that the minimum 'radial'
length is on the order of 12". No single 12" radial
is very useful . . . but there's a lot of them.
The longest radial goes out to 2 or more corners.
They might be as short as 20' but perhaps longer
if the antenna is not directly centered on the sheet.
[]
Obviously, the ground plane is not "ideal". But
then lots of satisfactory antenna installations
were 'grounded' to small plates welded to the
structure of a rag-n-tube airplane. Terrible
radials.
Your ground plane sheet is blessed with a few
pretty good radials and lots of not so good
but the SUM TOTAL of their effects at the base
of the antenna is substantial . . . and probably
quite adequate.
With respect to 'measuring' resistance between
the antenna base and the airframe, know that
very few installations get such treatment.
Practiced installers know that certain processes
ALWAYS yield good bonding. Further, those same
processes yield joints with good longevity in
service.
If your coax is good, the connectors are properly
installed AND you apply reliable processes for
getting high pressure connection between antenna
base and ground plane, an micro-ohmmeter test will
be quite predictable and therefore redundant.
Antenna choice, revisit?
Cobham/Comant isn't very positive about bent whip antennas for Comm
1. They say "Bent whips may not provide the best VSWR because of
proximity to the ground plane (aircraft skin), which can cause
reflections, plus they lack overall height. Remember, VHF antennas
"like" to be tall and straight for best operation." See FAQ #2.
Not true. It's the current flowing in about the bottom
20% of the antenna element that controls most of
an antenna's performance. In fact, it's common practice
to mechanically shorten an antenna with "capacity
hats" that act strongly in low current, high voltage
portion of the antenna element.
Bending the top of the antenna horizontal has little
effect on radiation pattern but will lower the frequency
of resonance.
Other than the antenna selection issue itself, this reading leads me
to three additional areas to investigate: ground plane symmetry,
ground plane size, and antenna mounting location on ground plane.
Go for the bonding . . . get that right and you're
98% done.
Re ground plane symmetry...
AC43.13-2B, paragraph 310(b) on page 27 says that "...ground plane
symmetry is critical." There is no reason or engineering data given
but its a fairly direct statement. After re-running the tests with
my 24" x 34" practice ground plane, I may cut it back to 24" x 24" to
see what VSWR readings I get with that size.
Please don't do this. AC43-13 was NOT crafted by
skilled practitioners of the arts or science of
building airplanes . . . That's another story.
See page 2 of
http://www.aeroelectric.com/articles/Getting_Started.pdf
Re ground plane size...
I understand that, in theory, the ideal ground plane is of infinite dimension.
That's the 'perfect'. . . the 'ideal' is more practical
(For an aside, see quote below.) Bob N. says the practical ideal is
a disc with a radius equal to one-quarter of the wavelength. An
on-line calculator told me that the wavelength at 122.95 MHz is
8'. One fourth of that is 2'. But that means the idealized disc
should have a diameter of 4'. My ground plane is only 24" wide --
half of what it should be. It isn't feasible to put a ground plane
4' wide in my plane -- most of it would have to curl up the sides of
the fuselage which would defeat the purpose anyhow. Moreover,
AC43.13-2B, paragraph 310(b), page 27, says most antennas require a
ground plane size of approximately 24" x 24".
Which supports the assertions I made earlier about
AC43-13 . . . 24 x 24 is a practical 'ideal' ground
plane for 174 Mhz given that the 4 best radials are
only 17" long.
Re antenna mounting location on ground plane...
In addition to the issue of the symmetry of the ground plane itself,
will it make a difference in VSWR if the antenna base is not mounted
in the center of the ground plane. As I mentioned in my earlier
post, I mounted the base about 1/3 of the distance along the long
axis so that the entire bent whip would be "covered" by the ground
plane. But if, electrically, the bent whip really behaves like the
straight piece of 12 AWG wire Bob N. used in his experiment, then
that seems to indicate that the antenna base needs to be installed in
the center of the ground plane, whether the ground plane is square or
rectangular.
Next steps...
I'm finishing up the final terminations on my feed lines and will
jury-rig an external ground plane in order to re-do the tests outside
the airplane as Bob N. suggested. I hope to have the new test data
to you in the next couple of days.
A good experiment . . . if you're really curious and
want to do it.
Bob . . .
________________________________________________________________________________
| From: | "Robert L. Nuckolls, III" <nuckolls.bob(at)aeroelectric.com> |
| Subject: | Re: coax antenna cable length |
At 09:32 PM 1/26/2011, you wrote:
>Guys,
>
> I have seen it suggested that when cutting off an antenna cable
>for your com radio, nav radio, etc., that you are supposed to cut
>the cable at EVEN multiples of one length of a dipole mast.
>
> Is it really all that critical what the cut-off measurement is for a coax
>cable for aircraft radios?
No.
Bob . . .
________________________________________________________________________________
| From: | "Robert L. Nuckolls, III" <nuckolls.bob(at)aeroelectric.com> |
| Subject: | Re: Comm Antenna & SWR: Grounding the Ground Plane: |
Ref: Bob N's. Message 27 Posted on 1-25-11
At 09:56 PM 1/26/2011, you wrote:
Bob N., et al,
Based on his reading of Figure 3-4 on page 28 of AC43.13-2B, my
Ham/EE/PE buddy asked me to check the resistance between the ground
plane and the ground system in my plane. (And yes, as you correctly
surmised, I'm using a B&C "forest of tabs" on the firewall for my
grounding system supplemented with your 37-pin Dsub ground bus for
avionics grounds mounted next to it.)
Check the chapter on grounding in the 'Connection.
Also check the antennas and feedline chapter.
DC power ground systems and antenna ground planes
have no functional relationship to each other.
It just so happens that they are sort of one chunk
of metal when your talking about a metal airplane.
But if the airplane is plastic, all commonality
ceases.
As expected, there was a complete open between my ground plane and
the grounding system in the airplane. This is consistent with your
comments in the message referenced above.
There are gazillions of antennas on tops of poles
that look like this:
Emacs!
None are even associated with the DC power system of the radio
at the other end of coax feed line.
But when, for example, a comm antenna is mounted on top of the wing
on a Cessna, I presume it is electrically bonded to the wing which
acts as the ground plane. But isn't the wing also part of the ground
system for the airplane itself? With a coax connector attached to
the antenna isn't there now two ground paths from the antenna to the
radio chassis in its mounting rack? Does this create a ground loop
and if so, are its effects positive, benign, or negative? Or is the
ground through the coax between the antenna and the radio isolated in
the radio chassis so the loop isn't completed? In thinking about my
setup (if I had an-all metal airplane), it seems like the loop would
be completed since the BNC connector at the radio end of the feed
line connects to another BNC connector that is mounted in the back
plane of the radio (Garmin 430W) chassis and it appears to me that
the pass-through BNC connector in the chassis back plane isn't
insulated from the radio chassis itself.
Your getting the investigation wrapped around
the axles of irrelevant data.
Get your ground plane bonding taken care of and
you're good to go.
Bob . . .
________________________________________________________________________________
| From: | Speedy11(at)aol.com |
Bob,
I'm sure you're familiar with this, but this blog is the first I've heard
of it.
More info is on the CAFE Blog at _http://blog.cafefoundation.org/?p=2439
_
(http://blog.cafefoundation.org/?p=2439) .
Stan Sutterfield
Thin, Light, Strong, and Energy Dense
by Dean Sigler on 01/07/2011
_2010=99s Nobel Prize in Physics _
(http://nobelprize.org/nobel_prizes/physics/laureates/2010/press.html) wen
t to Andre Geim and Konstantin Novoselov,
who extracted graphene from a piece of graphite when they stuck a piece
of
adhesive tape to it and peeled away a single atom-thick layer of the
thinnest, strongest material in the world.
The Nobel Prize web site explains other remarkable properties of this new
material. =9CAs a conductor of electricity it performs as well as
copper. As
a conductor of heat it outperforms all other known materials. It is almost
completely transparent, yet so dense that not even helium, the smallest ga
s
atom, can pass through it. Carbon, the basis of all known life on earth,
has surprised us once again.=9D
When mixed into plastics, graphene can turn them into conductors of
electricity while making them more heat resistant and mechanically robust.
Over 28,000 square feet per gram for a single layer of the material
=93 or
about the size of a football field
________________________________________________________________________________
| From: | "Robert L. Nuckolls, III" <nuckolls.bob(at)aeroelectric.com> |
At 10:01 PM 1/26/2011, you wrote:
>hi all,
> anyone have any experience with a wire tracer that they can
> recommend one? under $ 60 i hope.
> bob noffs
How about these?
http://tinyurl.com/49bj2pa
http://tinyurl.com/4hnlvvh
Bob . . .
________________________________________________________________________________
| From: | bob noffs <icubob(at)gmail.com> |
thanks bob,
anyone have a tracer they can recommend? one of the trackers on this
wedsite is the one i bought [one with long black antenna] from harbour
freight. purely worthless. when i called the tech guy to make arrangements
to ship it back he ''checked something'' then came back on the phone and
said just toss it and he would give me credit. on my card. also, the gb i
have been looking at is on one of these sites at a great price but i have
read that it works and that it doesn't. any feedback from a trusted
aerolectric follower would be appreciated.
bob noffs
On Wed, Jan 26, 2011 at 9:42 PM, Robert L. Nuckolls, III <
nuckolls.bob(at)aeroelectric.com> wrote:
> At 10:01 PM 1/26/2011, you wrote:
>
> hi all,
> anyone have any experience with a wire tracer that they can recommend one?
> under $ 60 i hope.
> bob noffs
>
>
> How about these?
>
> *http://tinyurl.com/49bj2pa*
>
> *http://tinyurl.com/4hnlvvh*
>
> Bob . . .
>
> *
>
> *
>
>
________________________________________________________________________________
| From: | bob noffs <icubob(at)gmail.com> |
thanks bob,
anyone have a tracer they can recommend? one of the trackers on this
wedsite is the one i bought [one with long black antenna] from harbour
freight. purely worthless. when i called the tech guy to make arrangements
to ship it back he ''checked something'' then came back on the phone and
said just toss it and he would give me credit. on my card. also, the gb i
have been looking at is on one of these sites at a great price but i have
read that it works and that it doesn't. any feedback from a trusted
aerolectric follower would be appreciated.
bob noffs
On Wed, Jan 26, 2011 at 9:42 PM, Robert L. Nuckolls, III <
nuckolls.bob(at)aeroelectric.com> wrote:
> At 10:01 PM 1/26/2011, you wrote:
>
> hi all,
> anyone have any experience with a wire tracer that they can recommend one?
> under $ 60 i hope.
> bob noffs
>
>
> How about these?
>
> *http://tinyurl.com/49bj2pa*
>
> *http://tinyurl.com/4hnlvvh*
>
> Bob . . .
>
> *
>
> *
>
>
________________________________________________________________________________
| From: | "Robert L. Nuckolls, III" <nuckolls.bob(at)aeroelectric.com> |
At 07:57 AM 1/27/2011, you wrote:
>thanks bob,
> anyone have a tracer they can recommend? one of the trackers on
> this wedsite is the one i bought [one with long black antenna] from
> harbour freight. purely worthless. when i called the tech guy to
> make arrangements to ship it back he ''checked something'' then
> came back on the phone and said just toss it and he would give me
> credit. on my card. also, the gb i have been looking at is on one
> of these sites at a great price but i have read that it works and
> that it doesn't.
You could build one. They function based on the
simple-ideas that drive the occasional need for
shielded wire. Electro-Static Coupling.
The 'transmitter' is usually a two-transistor
multi-vibrator or perhaps an IC audio amplifier
set up as an oscillator. The goal is to generate
a square-wave at about 400-1000 hz that has
VERY fast rise and fall times. In other words,
very high harmonic content. A 9v battery, two
transistors, 4 resistors and 4 capacitors would
do the trick.
The receiver is nothing more than a high gain
audio amplifier with a capacitive probe . . .
a metallic tip that can be placed in close
proximity to the wire ends being explored
for 'continuity'.
Capacitive coupling through the insulation
of the excited wire will come across as the
400-1000 Hz audio note. In fact, your probe is
really detecting the much higher frequency
harmonics that couple across the insulation
modulated at the audio rate.
Failure to function for any such product can
be a combination of factors. Edges of the
square wave are too slow. Amplifier in probe
is too low in gain. Receiver electronics poorly
shielded for the effects of other noises not
impressed through the probe.
These things appear really easy to make work
and they are. But it's a bit like learning
to make biscuits. Just having the ingredients
and a rough notion of how they go together
is not a recipe for success. There are
subtle but critical design goals to be
met.
I've seen some chatter on the DIY sites
suggesting that a transistor AM pocket radio
can be jeeped into a really good detector.
The transistor oscillator isn't a big deal
either.
Bob . . .
________________________________________________________________________________
| From: | "Robert L. Nuckolls, III" <nuckolls.bob(at)aeroelectric.com> |
| Subject: | Re: Comm Antenna & SWR: More Information |
>
>Personally, I have never flown a Bonanza that was equipped with the
>tail cone antenna, but I have personally spoken to a pilot who has
>flown his that way in heavy IFR operations for over twenty years.
>Just how good do antennas really NEED to be?
>
>Mike also was a big exponent of using a set of VHF Navigation blades
>mounted as far back on the Bonanza fuselage as possible. The
>manufacturer of the antennas said they were way too close to the
>tail feathers to work properly. I have personally mounted several
>blade antennas in that position and they have all worked very well.
>
>Just some data for further thought.
And good data it is.
Folks often get their airplane antenna issues stirred into
a stew of some good and not-so-good data about "antenna
struggles". The majority of data in the wild comes from
folks wanting to watch tv from a station 60 miles away,
a ham operator who wishes to extract .5 microvolt signals
from a universe of noise, and the two way radio company
attempting to satisfy a fleet customer with 100 vehicles
that wander afar from home base.
All of these situations might gain a measure of improvement
by fine tuning swr, radiation patterns, coax losses,
installation losses, etc.
THEN you have airplanes. Airplanes almost never offer
opportunities to install the best antennas we know how
to do for reasons unique to airplanes. Weird shapes,
not enough acreage, aerodynamic buffeting, aerodynamic
drag, and general ugliness on an otherwise "fast" looking
airplane.
The really cool thing about airplane antennas is that
a wet string hung out the window would probably
suffice for 90% of the aviator's communications needs.
We got into a discussion on the List many years ago
about the relative utility of the new line of miniature
transceivers with puny transmitters . . . 1 to 2 watts.
There was a lot of concern for overall communications
performance. However, most worries were grounded in
memories of having witnessed John Wayne's harrowing
experiences exacerbated by too week a radio signal while
wrestling with 5 bad guys and a string of simultaneous
systems failures.
The environmental influences on aviation signal
strength are (1) line of sight limitations due to curvature
of the earth, (2) path loss (attenuation as a function
of distance and frequency) and (3) environmental
noise at the receive end. It turns out that a couple of
1 watt transceivers talking to each other on rudimentary
antennas had a range on the order of 1000 miles in free space.
As a practical matter, we rarely need to talk with
a facility that is more than 50 miles away. For an
airplane at 2000 AGL talking to a facility with 40'
high antennas, line-of-sight distance is 70+
miles. Bottom line: the NEED for high power
and finely tuned performance in antennas/feedlines
for the way we use radios in our airplanes is
exceedingly rare.
This discussion about SWR, etc is certainly
valuable for understanding the simple-ideas that
drive system performance. At the same time, I hope
that Bob doesn't spend a great deal of time seeking
the holy grail of 1:1 SWR, perfectly circular radiation
patterns and zero loss coax.
Nearly a century of practical experience has demonstrated
that (1) the grail is not attainable and (2) wouldn't
make an observable difference if it were attained.
Bob . . .
________________________________________________________________________________
| From: | "Robert L. Nuckolls, III" <nuckolls.bob(at)aeroelectric.com> |
| Subject: | Comm Antenna & SWR: More Information |
At 11:05 PM 1/26/2011, you wrote:
>One more antenna that is not done right and still works fine. The
>ELT on many RV's is horizontal and inside the tail cone fairing. Or
>in the baggage area with only the top few inches not close to
>metal. Neither of these install techniques have good ground planes
>nor the correct orientation but they work with both the 121.5 and
>the 406 versions of ELT
Excellent point. This feeds directly into the assertions
I made in the post a few minutes ago. The satellite flying
overhead has no line-of-sight limitations nor is it plagued
with line noise, ignition noise and strong local radio
stations. It's as close as you can get to the ideal
receiving environment.
This is a large component of the recipe for success
in spite of poorly crafted or even crash-damaged
beacon antennas.
Bob . . .
________________________________________________________________________________
| From: | "Robert L. Nuckolls, III" <nuckolls.bob(at)aeroelectric.com> |
At 11:29 PM 1/26/2011, you wrote:
>Bob,
>I'm sure you're familiar with this, but this blog is the first I've
>heard of it.
>More info is on the CAFE Blog at
><http://blog.cafefoundation.org/?p=2439>http://blog.cafefoundation.org/?p=2439.
>Stan Sutterfield
>
>
Cool! Thanks for the heads-up.
Bob . . .
________________________________________________________________________________
| From: | "Noel Loveys" <noelloveys(at)yahoo.ca> |
| Subject: | coax antenna cable length |
That's the first I've heard of anything like this. As Bob has said, the
longer the feed cable (coax) the closer the match to the radio will be to 50
Ohms but you will then also have to contend with line losses.
The question than has to be what to do with the access cable? If you coil
it up you can be opening a whole new can or worms. Re-routing it can also
cause problems. Best to decide on the best possible routing and install
leaving just enough cable for drip loops.
Noel
From: owner-aeroelectric-list-server(at)matronics.com
[mailto:owner-aeroelectric-list-server(at)matronics.com] On Behalf Of Mike
Welch
Sent: January 26, 2011 11:02 PM
Subject: AeroElectric-List: coax antenna cable length
Guys,
I have seen it suggested that when cutting off an antenna cable
for your com radio, nav radio, etc., that you are supposed to cut
the cable at EVEN multiples of one length of a dipole mast.
In the example of a com radio, one article states the dipole length
of a com radio to be 20". Therefore, you should double this, and
use this new length to calculate your final minimum cable length.
Like this; dipole = 20", so our increment would be 40". Now,
beginning at the back of the radio (not at a junction of a pigtail),
start counting off 40" increments until we have enough cable to
comfortably reach the actual antenna. Meaning; only cut the cable at
40", 80", 120", 160", 200", etc.
If, after we've done an excellent routing of the cable, we find our
antenna is not located at a 40" increment, then we should proceed
to the next full length of our 40" increment prior to cutting the cable.
Here's my question; I read from a prominent, nationally known,
avionics guru that this is not all that necessary. If I recall correctly,
he said he has done SWR tests, and the cable length (cut off at even
multiples) had little effect on the antennas performance. In other
words, it didn't really matter what the cable length was, i.e.., 180"
or 205", etc.
If I'm a little fuzzy on my facts here, it's because this information
is from several years ago. But, after all these years, I really would
like to now the facts!!
Is it really all that critical what the cut-off measurement is for a coax
cable for aircraft radios?
Thanks, Mike Welch
________________________________________________________________________________
| From: | "Don" <dsvs(at)ca.rr.com> |
| Subject: | Comm Antenna & SWR: More Information |
Hi Bob,
Don Panier at www.deltapopaviation.cpm makes and sells com, nav, adsb aprs
and transponder antennas that take their connection to the ground plane from
the mounting screws. The antenna does not have any metal contact on the
base other than the mounting screws. These work well in composite and metal
ac.
-----Original Message-----
From: owner-aeroelectric-list-server(at)matronics.com
[mailto:owner-aeroelectric-list-server(at)matronics.com] On Behalf Of Robert L.
Nuckolls, III
Sent: Thursday, January 27, 2011 7:19 AM
Subject: RE: AeroElectric-List: Comm Antenna & SWR: More Information
At 11:05 PM 1/26/2011, you wrote:
>One more antenna that is not done right and still works fine. The
>ELT on many RV's is horizontal and inside the tail cone fairing. Or
>in the baggage area with only the top few inches not close to
>metal. Neither of these install techniques have good ground planes
>nor the correct orientation but they work with both the 121.5 and
>the 406 versions of ELT
Excellent point. This feeds directly into the assertions
I made in the post a few minutes ago. The satellite flying
overhead has no line-of-sight limitations nor is it plagued
with line noise, ignition noise and strong local radio
stations. It's as close as you can get to the ideal
receiving environment.
This is a large component of the recipe for success
in spite of poorly crafted or even crash-damaged
beacon antennas.
Bob . . .
________________________________________________________________________________
| From: | "Don" <dsvs(at)ca.rr.com> |
| Subject: | Comm Antenna & SWR: More Information |
Make that www.deltapopaviation.com
-----Original Message-----
From: owner-aeroelectric-list-server(at)matronics.com
[mailto:owner-aeroelectric-list-server(at)matronics.com] On Behalf Of Don
Sent: Thursday, January 27, 2011 3:46 PM
Subject: RE: AeroElectric-List: Comm Antenna & SWR: More Information
Hi Bob,
Don Panier deltapopaviation.makes and sells com, nav, adsb aprs
and transponder antennas that take their connection to the ground plane from
the mounting screws. The antenna does not have any metal contact on the
base other than the mounting screws. These work well in composite and metal
ac.
-----Original Message-----
From: owner-aeroelectric-list-server(at)matronics.com
[mailto:owner-aeroelectric-list-server(at)matronics.com] On Behalf Of Robert L.
Nuckolls, III
Sent: Thursday, January 27, 2011 7:19 AM
Subject: RE: AeroElectric-List: Comm Antenna & SWR: More Information
At 11:05 PM 1/26/2011, you wrote:
>One more antenna that is not done right and still works fine. The
>ELT on many RV's is horizontal and inside the tail cone fairing. Or
>in the baggage area with only the top few inches not close to
>metal. Neither of these install techniques have good ground planes
>nor the correct orientation but they work with both the 121.5 and
>the 406 versions of ELT
Excellent point. This feeds directly into the assertions
I made in the post a few minutes ago. The satellite flying
overhead has no line-of-sight limitations nor is it plagued
with line noise, ignition noise and strong local radio
stations. It's as close as you can get to the ideal
receiving environment.
This is a large component of the recipe for success
in spite of poorly crafted or even crash-damaged
beacon antennas.
Bob . . .
________________________________________________________________________________
| From: | "Noel Loveys" <noelloveys(at)yahoo.ca> |
| Subject: | Comm Antenna & SWR: Grounding the Ground Plane: |
Ref: Bob N's. Message 27 Posted on 1-25-11
With your antenna and the BNC connector in place there should be a dead
short from the ground plane to the braid of your coax. Mind you the other
end of the coax should be grounded to the case of the radio.
Noel
-----Original Message-----
From: owner-aeroelectric-list-server(at)matronics.com
[mailto:owner-aeroelectric-list-server(at)matronics.com] On Behalf Of Bob
Falstad
Sent: January 26, 2011 11:27 PM
Subject: AeroElectric-List: Comm Antenna & SWR: Grounding the Ground Plane:
Ref: Bob N's. Message 27 Posted on 1-25-11
Bob N., et al,
Based on his reading of Figure 3-4 on page 28 of AC43.13-2B, my Ham/EE/PE
buddy asked me to check the resistance between the ground plane and the
ground system in my plane. (And yes, as you correctly surmised, I'm using a
B&C "forest of tabs" on the firewall for my grounding system supplemented
with your 37-pin Dsub ground bus for avionics grounds mounted next to it.)
As expected, there was a complete open between my ground plane and the
grounding system in the airplane. This is consistent with your comments in
the message referenced above.
But when, for example, a comm antenna is mounted on top of the wing on a
Cessna, I presume it is electrically bonded to the wing which acts as the
ground plane. But isn't the wing also part of the ground system for the
airplane itself? With a coax connector attached to the antenna isn't there
now two ground paths from the antenna to the radio chassis in its mounting
rack? Does this create a ground loop and if so, are its effects positive,
benign, or negative? Or is the ground through the coax between the antenna
and the radio isolated in the radio chassis so the loop isn't completed? In
thinking about my setup (if I had an-all metal airplane), it seems like the
loop would be completed since the BNC connector at the radio end of the feed
line connects to another BNC connector that is mounted in the back plane of
the radio (Garmin 430W) chassis and it appears to me that the pass-through
BNC connector in the chassis back plane isn't insulated from the radio
chassis itself.
Your thought and comments?
Best regards,
Bob Falstad
GlaStar N248BF
________________________________________________________________________________
| From: | "Noel Loveys" <noelloveys(at)yahoo.ca> |
| Subject: | Comm Antenna & SWR: More Information |
The only ground plane I know of which is close to infinite is salt water.
Fibre glass boats commonly use the ocean itself as a ground plane for
radio... Believe me they can have problems too.
Noel
From: owner-aeroelectric-list-server(at)matronics.com
[mailto:owner-aeroelectric-list-server(at)matronics.com] On Behalf Of Robert L.
Nuckolls, III
Sent: January 26, 2011 10:44 PM
Subject: Re: AeroElectric-List: Comm Antenna & SWR: More Information
Additional detail about my ground plane installation.
My ground plane isn't symmetrical (and, contrary to my earlier post, it is
actually 24" x 34", not 24" x 36" -- I had cut 2" off the length so that it
would fit in the space I had available). I also didn't mention that I cut
two slots in the ground plane so that it would fit over a couple of supports
for the floors in my baggage compartment. These slots are ~3" x 1/2" and
are about 10" aft of the antenna base and about 4" either side of the
fuselage centerline. Will these slots in the ground plane degrade the
ground plane's performance?
Not much . . . if any. Let's consider the way
a ground plane works. In an earlier post I
explained how the sum total of 4 'prefect'
radials routed 80% plus of energy delivered
to the end of the coax to be delivered to
the antenna.
Now, if you draw say 100 equally spaced lines
from the antenna location on your ground plane
out to the edge, we can see that the minimum 'radial'
length is on the order of 12". No single 12" radial
is very useful . . . but there's a lot of them.
The longest radial goes out to 2 or more corners.
They might be as short as 20' but perhaps longer
if the antenna is not directly centered on the sheet.
[]
Obviously, the ground plane is not "ideal". But
then lots of satisfactory antenna installations
were 'grounded' to small plates welded to the
structure of a rag-n-tube airplane. Terrible
radials.
Your ground plane sheet is blessed with a few
pretty good radials and lots of not so good
but the SUM TOTAL of their effects at the base
of the antenna is substantial . . . and probably
quite adequate.
With respect to 'measuring' resistance between
the antenna base and the airframe, know that
very few installations get such treatment.
Practiced installers know that certain processes
ALWAYS yield good bonding. Further, those same
processes yield joints with good longevity in
service.
If your coax is good, the connectors are properly
installed AND you apply reliable processes for
getting high pressure connection between antenna
base and ground plane, an micro-ohmmeter test will
be quite predictable and therefore redundant.
Antenna choice, revisit?
Cobham/Comant isn't very positive about bent whip antennas for Comm 1. They
say "Bent whips may not provide the best VSWR because of proximity to the
ground plane (aircraft skin), which can cause reflections, plus they lack
overall height. Remember, VHF antennas "like" to be tall and straight for
best operation." See FAQ #2.
Not true. It's the current flowing in about the bottom
20% of the antenna element that controls most of
an antenna's performance. In fact, it's common practice
to mechanically shorten an antenna with "capacity
hats" that act strongly in low current, high voltage
portion of the antenna element.
Bending the top of the antenna horizontal has little
effect on radiation pattern but will lower the frequency
of resonance.
Other than the antenna selection issue itself, this reading leads me to
three additional areas to investigate: ground plane symmetry, ground plane
size, and antenna mounting location on ground plane.
Go for the bonding . . . get that right and you're
98% done.
Re ground plane symmetry...
AC43.13-2B, paragraph 310(b) on page 27 says that "...ground plane symmetry
is critical." There is no reason or engineering data given but its a fairly
direct statement. After re-running the tests with my 24" x 34" practice
ground plane, I may cut it back to 24" x 24" to see what VSWR readings I get
with that size.
Please don't do this. AC43-13 was NOT crafted by
skilled practitioners of the arts or science of
building airplanes . . . That's another story.
See page 2 of
http://www.aeroelectric.com/articles/Getting_Started.pdf
Re ground plane size...
I understand that, in theory, the ideal ground plane is of infinite
dimension.
That's the 'perfect'. . . the 'ideal' is more practical
(For an aside, see quote below.) Bob N. says the practical ideal is a disc
with a radius equal to one-quarter of the wavelength. An on-line calculator
told me that the wavelength at 122.95 MHz is 8'. One fourth of that is 2'.
But that means the idealized disc should have a diameter of 4'. My ground
plane is only 24" wide -- half of what it should be. It isn't feasible to
put a ground plane 4' wide in my plane -- most of it would have to curl up
the sides of the fuselage which would defeat the purpose anyhow. Moreover,
AC43.13-2B, paragraph 310(b), page 27, says most antennas require a ground
plane size of approximately 24" x 24".
Which supports the assertions I made earlier about
AC43-13 . . . 24 x 24 is a practical 'ideal' ground
plane for 174 Mhz given that the 4 best radials are
only 17" long.
Re antenna mounting location on ground plane...
In addition to the issue of the symmetry of the ground plane itself, will it
make a difference in VSWR if the antenna base is not mounted in the center
of the ground plane. As I mentioned in my earlier post, I mounted the base
about 1/3 of the distance along the long axis so that the entire bent whip
would be "covered" by the ground plane. But if, electrically, the bent whip
really behaves like the straight piece of 12 AWG wire Bob N. used in his
experiment, then that seems to indicate that the antenna base needs to be
installed in the center of the ground plane, whether the ground plane is
square or rectangular.
Next steps...
I'm finishing up the final terminations on my feed lines and will jury-rig
an external ground plane in order to re-do the tests outside the airplane as
Bob N. suggested. I hope to have the new test data to you in the next
couple of days.
A good experiment . . . if you're really curious and
want to do it.
Bob . . .
________________________________________________________________________________
| From: | "Noel Loveys" <noelloveys(at)yahoo.ca> |
I think there is a typo there... I believe they mean to say,
=9CEven helium the smallest gas atom, cannot pass through
it=9D.
Also isn=99t hydrogen smaller than helium? One electron is
smaller than two on the atomic level. However on a molecular level
it=99s true. Helium being inert is He. Hydrogen being so active
is H2 a lot larger.
Noel
From: owner-aeroelectric-list-server(at)matronics.com
[mailto:owner-aeroelectric-list-server(at)matronics.com] On Behalf Of
Speedy11(at)aol.com
Sent: January 27, 2011 12:59 AM
Subject: AeroElectric-List: Graphene
Bob,
I'm sure you're familiar with this, but this blog is the first I've
heard of it.
More info is on the CAFE Blog at
http://blog.cafefoundation.org/?p=2439.
Stan Sutterfield
Thin, Light, Strong, and Energy Dense
by Dean Sigler on 01/07/2011
<http://nobelprize.org/nobel_prizes/physics/laureates/2010/press.html>
2010=99s Nobel Prize in Physics went to Andre Geim and Konstantin
Novoselov, who extracted graphene from a piece of graphite when they
stuck a piece of adhesive tape to it and peeled away a single atom-thick
layer of the thinnest, strongest material in the world.
The Nobel Prize web site explains other remarkable properties of this
new material. =9CAs a conductor of electricity it performs as
well as copper. As a conductor of heat it outperforms all other known
materials. It is almost completely transparent, yet so dense that not
even helium, the smallest gas atom, can pass through it. Carbon, the
basis of all known life on earth, has surprised us once again.=9D
When mixed into plastics, graphene can turn them into conductors of
electricity while making them more heat resistant and mechanically
robust.
Over 28,000 square feet per gram for a single layer of the material
=93 or about the size of a football field
________________________________________________________________________________
| From: | "Robert L. Nuckolls, III" <nuckolls.bob(at)aeroelectric.com> |
| Subject: | coax antenna cable length |
At 06:27 PM 1/27/2011, you wrote:
>That's the first I've heard of anything like this. As Bob has said,
>the longer the feed cable (coax) the closer the match to the radio
>will be to 50 Ohms but you will then also have to contend with line losses.
>
>The question than has to be what to do with the access cable? If
>you coil it up you can be opening a whole new can or
>worms. Re-routing it can also cause problems. Best to decide on
>the best possible routing and install leaving just enough cable for drip loops.
I did not intended proffer the idea that one
would purposely ADD coax to a feedline for
the purpose of reducing SWR. It is because
longer feedlines ADD losses that the SWR
appears to improve while in fact, the
effects of real SWR are being masked by
those losses. It was an observation of
fact, not a recommendation.
Bob . . .
________________________________________________________________________________
| From: | "Robert L. Nuckolls, III" <nuckolls.bob(at)aeroelectric.com> |
| Subject: | Comm Antenna & SWR: More Information |
> The antenna does not have any metal contact on the
>base other than the mounting screws. These work well in composite and metal
>ac.
Virtually ALL comm antennas make ground plane
connections only through their mounting screws.
I've seen installation manuals suggest that the
skin of the airplane under the base of an antenna
be cleaned to the bare metal . . . ostensibly for
the purpose of improving on the antenna to airplane
bonding.
Bonding is achieved by HIGH PRESSURE joints in
metallic fasteners. I crafted this drawing about
5 years ago. . .
http://aeroelectric.com/Pictures/Antenna/Comm_Antenna_Installation.gif
I DID suggest that the stock gasket shipped with
many antennas be discarded and that the base be
moisture sealed to the skin with a bead of RTV.
However, you'll not an emphasis on clean metal
circles around each of the mounting fasteners
where we'll exploit the pressure that cranking
down on the nut will offer.
Stray outside the clamp-up radius around each
bolt very far, and any notion of long term, high
quality boding between the parts becomes a fantasy.
Bob . . .
________________________________________________________________________________
| From: | "Robert L. Nuckolls, III" <nuckolls.bob(at)aeroelectric.com> |
| Subject: | Comm Antenna & SWR: More Information |
At 07:12 PM 1/27/2011, you wrote:
>The important thing with com antennas is good omnidirectional ( all
>directions ) coverage.
"Good" is non-quantified. I've seen horizontal pattern
plots for comm antennas that had large (10db or more)
variations around the compass . . . but these antennas
proved adequate to the performance necessary.
>A horizontally polarized antenna in a tailcone, outside of having
>too small a ground plane, will have a dead area in front of the
>plane and another one behind it.
???? The VOR antenna whiskers are horizontally polarized
dipole with major lobes fore and aft with nulls off to the
sides. Further, dipole antennas require no ground plane.
> I can't see how this can be considered good for airplanes heading
> into or away from a control zone.
No such "null" exists fore and aft.
>
>Many large aircraft actually have antennae above and below the
>fuselage to allow communication with other aircraft as well as ground.
???? Antenna placement is largely a matter of separation
between the antennas for similar systems . . . and judicious
use of real estate. Once an airplane is airborne, relative
differences between top and bottom mounted antennas is
insignificant.
Bob . . .
________________________________________________________________________________
| From: | "Don" <dsvs(at)ca.rr.com> |
| Subject: | Comm Antenna & SWR: More Information |
Thanks Bob. I was led to believe that the antenna and skin needed tp be
paint free and making good contact. This is what the instructions that came
with my commant and Avidyne Ryan antennas had to say. Glad that I mow
understand the actual requirements.
-----Original Message-----
From: owner-aeroelectric-list-server(at)matronics.com
[mailto:owner-aeroelectric-list-server(at)matronics.com] On Behalf Of Robert L.
Nuckolls, III
Sent: Thursday, January 27, 2011 5:41 PM
Subject: RE: AeroElectric-List: Comm Antenna & SWR: More Information
> The antenna does not have any metal contact on the
>base other than the mounting screws. These work well in composite and metal
>ac.
Virtually ALL comm antennas make ground plane
connections only through their mounting screws.
I've seen installation manuals suggest that the
skin of the airplane under the base of an antenna
be cleaned to the bare metal . . . ostensibly for
the purpose of improving on the antenna to airplane
bonding.
Bonding is achieved by HIGH PRESSURE joints in
metallic fasteners. I crafted this drawing about
5 years ago. . .
http://aeroelectric.com/Pictures/Antenna/Comm_Antenna_Installation.gif
I DID suggest that the stock gasket shipped with
many antennas be discarded and that the base be
moisture sealed to the skin with a bead of RTV.
However, you'll not an emphasis on clean metal
circles around each of the mounting fasteners
where we'll exploit the pressure that cranking
down on the nut will offer.
Stray outside the clamp-up radius around each
bolt very far, and any notion of long term, high
quality boding between the parts becomes a fantasy.
Bob . . .
________________________________________________________________________________
| From: | "Robert L. Nuckolls, III" <nuckolls.bob(at)aeroelectric.com> |
| Subject: | Comm Antenna & SWR: More Information |
At 10:36 PM 1/27/2011, you wrote:
>
>Thanks Bob. I was led to believe that the antenna and skin needed tp be
>paint free and making good contact. This is what the instructions that came
>with my commant and Avidyne Ryan antennas had to say. Glad that I mow
>understand the actual requirements.
It's not uncommon for folks who specialize in
one technology to be weak in peripheral technologies.
Anyone who has worked in the EMC lab to identify and
control the transfer of RF energy understands that
large area, low pressure, open-to-atmosphere interfaces
between two metallic surfaces is NOT a bond of any useful
kind. Gas tight over lifetime of the airplane is
the goal.
If one could "tack weld" the base of an antenna
to the skin of the airplane in a half-dozen places
around the edge, the RF bonding guys would be
delighted. The next best thing is to make sure the
conduction footprints around the mounting bolts
pretend like they're welded to the airplane
Bob . . .
________________________________________________________________________________
| From: | "Robert L. Nuckolls, III" <nuckolls.bob(at)aeroelectric.com> |
| Subject: | ELT antenna performance |
At 11:54 PM 1/27/2011, you wrote:
>Bob and all,
>During an emergency landing too many aircraft go over on their backs.
or suffer severe deformation/disassembly
> I suspect that the back contact and sliding in too many instances
> scrapes off or otherwise damages antenna like the ELT typically use.
which is why the preferred location for ELT antenna
is just forward of the vertical fin. Studies of
wreckage remains determined that this was the lowest
risk location for the antenna . . . unfortunately,
"lowest" is not a nice number near zero.
>
> From that situation, I have wondered about a design concept that
> would allow the ELT to feed either two or one antennas with enough
> radiation to get someone's attention. The thought goes something
> like this. Have an antenna both top and bottom of the fuselage
> region. Hoping that one survives the impact and will radiate the ELT signal.
Having the system upside down is not as deleterious
as one might imagine. UHF behaves quite a bit differently
than VHF.
When I first got into electronics as a profession,
I was working for a two-way radio company in Wichita.
We serviced a few systems in the 72 mHz band but
most were in the vicinity of 150 mHz and a few
were up about 450.
This was all vacuum tube stuff. The 450 mHz
equipment was at the upper fringe of what
was practical. It was harder to develop power,
losses in feedlines was higher, keeping
receiver sensitivity to less than 1 microvolt
was more demanding. All-in-all, higher
cost of ownership.
You'd think that customers would shy away from
this equipment. On the contrary. Antennas were
more efficient. Terrestrial noise was a small
influence. Signals behaved much better in the
confines of tall buildings. The cab companies
wouldn't have anything different. The police
wanted it but the FCC decreed that public
services will conduct business in the 150 mHz
band. 150 mHz was subject to much more multi-
path nulls and noise.
121.5 mHz was picked for the first ELTs
because it was a frequency already serviced
by aviation communication services. Same
with 243 albeit military. The idea was
that folks having nothing better to do
on long trips might monitor the emergency
frequencies and report any contacts. Heaven
knew that the satellite location technology
was EXCEEDINGLY crude. Location accuracy was
poor (100 square miles or more), it took
three or more satellite passes to get that
good (meaning many hours after first contact)
and that assumed that they could sort out
the distressed aircraft from several dozen
false triggers that every satellite could
hear within it's line-of-sight cone.
Combine this with the relatively poor
performance of VHF propagation in general
and you begin to see why the system was
doomed to poor performance from the
beginning. 6% find-rates was considered
great performance by some.
Then came solid state UHF electronics
where communications at 2,000 Mhz was
no big deal. Add ship's i.d. GPS location
features to the ELT's transmitted signals and
that 6% number took a big jump.
They have a better chance of sorting
out your distress from other people's
false alarms.Haven't seen the latest
figures but I'll bet there are no
more than 25% of found wrecks where
attributed to ELT performance where
rescue outcomes were good . . .
I'd be delighted to be wrong.
Getting back to upside-down wrecks.
The UHF propagation performance is so
much better than the old 121.5/243
junk that antenna orientation and
shadowing is much less critical. I've
not been privy to detailed discussion
on ELT systems. But given what I know
of UHF propagation behavior, if the
system is not physically disabled,
the system is going to perform about
as well as expected irrespective
of wreckage configuration.
But the real bottom line is, what
is the return-on-investment for having
installed an ELT? How many wrecks
in the history of all aviation crashes
would have had a better outcome for
the occupants had the guys in white
coats with stretchers arrived say
within two hours of the crash?
In other words, what percentage of
all events resulted in occupants
surviving for hours to days but
unable to fend for themselves due
to non-lethal injury or simple lack
of transport?
The ELT makes a lot of sense for
over-water flight where there is
higher probability of non-lethal
landing and perhaps days of post
crash survival on a float. But
pile an airplane into a mountain
or even average terrain at night
and the ELT becomes more of a
whistle in the dark. If you really
want the folks in white coats to
show up fast, make sure you've
added the GPS position data option.
At least they KNOW where you are.
Now the problem is to get to
you with what ever resources are
available for the task. Those
resources are dwindling . . . but
that's another issue.
>
>Any thoughts about a design that could "reasonably" match and feed
>either two (if both survive) or the remaining antenna....
Sure. You could install rugged, flush
mounted slot antennas on top and bottom
of the tail. Use a power divider to feed
both antennas.
This would demand some analysis and perhaps
demonstrated experiments to determine
it was really that much better. I suspect
that the numbers guys would find that
going to dual, robust antennas would
double installation costs while making that
25% go up to 26.2% or some such.
I'm pretty sure it's been explored. The
ELT guys would be DELIGHTED to have dual
robust antennas added to the mandate for
installing such systems. If it made any
sense at all, they'd be doing it.
Bob . . .
________________________________________________________________________________
| From: | "Robert L. Nuckolls, III" <nuckolls.bob(at)aeroelectric.com> |
| Subject: | Unfortunate Antenna Instructions |
I've been given a copy of S-H antenna installation
instructions for review. I have the following observations
to share with members of the List. The article has
been posted at:
http://tinyurl.com/4cwq4yy
ADJUSTING the ANTENNA CABLE LENGTH
The process described under this title is a salute
to an old hangar myth that antenna system performance
can be improved by cutting coax feed lines to (1) multiples
of half-wavelengths or (2) maximize measured field strength
on some particular frequency.
As we discussed last week, the ONLY time that observable
effects are affected by length of the transmission line
is when the SWR on that line is high. The most profound
effects for fiddling with length will be noted when SWR
is a lot higher than what is traditionally accepted as
optimum performance. 3:1 or better.
This myth has roots that go back a long way in aviation
history. I recall similar discussions back in the 60's.
I would challenge the publisher of any such document to
search any engineering text and/or any ARRL publication
on amateur built antennas. They will not find any similar
suggestion anywhere. The adequately designed antenna
presents a load to the feedline that has no observable,
deleterious effects on system performance.
An interesting feature of the S-H suggestion is that
even if there WERE a valid reason for crafting an even-
multiples-half-wave transmission line, the coax cuts
would NOT be multiples of the free-space wavelength used
to design the antenna.
Propagation velocity of energy down a transmission line
is SLOWER than in free space. Depending on how the coax is
made, the VELOCITY FACTOR will be some number near .66
This means that for a 1/4-wave, 24" antenna element length
a 1/2 wave in coax would NOT be 48" but 48 x .66 or
31.5 inches.
Unfortunately, the idea published in this document is not
only non-sense, it is poorly implemented based on bad science.
INSTALLING BNC CONNECTORS
Finally, the tri-axial cable called out was designed for
use in systems were special connectors maintain SEPARATED
shield integrity throughout the system. VERY expensive
and rare connectors. On the other hand, RG-58 has been
handily replaced throughout the TC aircraft world with
RG-400 or RG142 which are DOUBLE LAYER bi-axial feedlines
that accept the standard RG-58 connectors with no
fabrication acrobatics.
It's unfortunate that this publication has been circulated
to S-H customers for 14 years. It has no doubt generated a lot
of unnecessary no-value added taxation of their customer's
time, talents and resources.
Bob . . .
________________________________________________________________________________
| From: | "jonlaury" <jonlaury(at)impulse.net> |
Try www.allelectroincs.com , cat#28, $12
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=328832#328832
________________________________________________________________________________
| From: | Richard Tasker <retasker(at)optonline.net> |
| Subject: | Re: ELT antenna performance |
Hey Bob, not to pick nits , but you are the example here after all... ;-)
mHz - millihertz
MHz - megahertz
Dick Tasker
Robert L. Nuckolls, III wrote:
> When I first got into electronics as a profession,
> I was working for a two-way radio company in Wichita.
> We serviced a few systems in the 72 mHz band but
> most were in the vicinity of 150 mHz and a few
> were up about 450.
>
> This was all vacuum tube stuff. The 450 mHz
> equipment was at the upper fringe of what
> was practical. It was harder to develop power,
> losses in feedlines was higher, keeping
> receiver sensitivity to less than 1 microvolt
> was more demanding. All-in-all, higher
> cost of ownership.
>
> You'd think that customers would shy away from
> this equipment. On the contrary. Antennas were
> more efficient. Terrestrial noise was a small
> influence. Signals behaved much better in the
> confines of tall buildings. The cab companies
> wouldn't have anything different. The police
> wanted it but the FCC decreed that public
> services will conduct business in the 150 mHz
> band. 150 mHz was subject to much more multi-
> path nulls and noise.
>
> 121.5 mHz was picked for the first ELTs
> because it was a frequency already serviced
> by aviation communication services. Same
> with 243 albeit military.
________________________________________________________________________________
| From: | "Robert L. Nuckolls, III" <nuckolls.bob(at)aeroelectric.com> |
| Subject: | Re: ELT antenna performance |
At 11:15 AM 1/28/2011, you wrote:
>Hey Bob, not to pick nits , but you are the example here after all... ;-)
>
>mHz - millihertz
>
>MHz - megahertz
>
>Dick Tasker
You're quite correct. Unfortunately, when trying
to bang out a timely but extensive reply, I don't
have the luxury of coming back to edit it tomorrow
to attempt a 99% clean posting.
When I go back and read my past postings, it's
not unusual to get whacked by spelling/semantics
issues. I'll just have to beg the Lists indulgence.
That doesn't mean I don't want to hear from
folks when I've stubbed my toe. Just be forewarned
that in spite of your most honorable efforts, my
head will probably continue to run out in front of
fingers on the keyboard.
Thanks for the heads-up!
Bob . . .
________________________________________________________________________________
| From: | Bob McCallum <robert.mccallum2(at)sympatico.ca> |
John;
Check the link you posted. It leads to a website phishing for cell phone
numbers.
I suspect that when you wrote "allelectroincs" you might have meant
"allelectronics", but catalogue #28 does not appear to exist on their
website and all of their part numbers appear to consist of an alpha prefix
followed by a dash and then a number. There do not appear to be any numbers
fitting your posting.
Please clarify.
Bob McC
> -----Original Message-----
> From: owner-aeroelectric-list-server(at)matronics.com
[mailto:owner-aeroelectric-list-
> server(at)matronics.com] On Behalf Of jonlaury
> Sent: Friday, January 28, 2011 11:39 AM
> To: aeroelectric-list(at)matronics.com
> Subject: AeroElectric-List: Re: lan tracer
>
>
> Try www.allelectroincs.com , cat#28, $12
>
>
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=328832#328832
>
>
>
>
>
>
>
> _-
> ====================================================
> ======
> _-
> ====================================================
> ======
> _-
> ====================================================
> ======
> _-
> ====================================================
> ======
>
>
________________________________________________________________________________
| From: | "Noel Loveys" <noelloveys(at)yahoo.ca> |
| Subject: | coax antenna cable length |
What I was getting at was not to reroute the wire or coil it up to take care
of excess. Cut it off. I think you agree as I agree the longer coax
appears to have a better swr but in fact it has greater line losses.
Certainly I agree that no one should ever add length to the feed wire to
achieve a mach.
Noel
-----Original Message-----
From: owner-aeroelectric-list-server(at)matronics.com
[mailto:owner-aeroelectric-list-server(at)matronics.com] On Behalf Of Robert L.
Nuckolls, III
Sent: January 27, 2011 10:00 PM
Subject: RE: AeroElectric-List: coax antenna cable length
At 06:27 PM 1/27/2011, you wrote:
>That's the first I've heard of anything like this. As Bob has said,
>the longer the feed cable (coax) the closer the match to the radio
>will be to 50 Ohms but you will then also have to contend with line losses.
>
>The question than has to be what to do with the access cable? If
>you coil it up you can be opening a whole new can or
>worms. Re-routing it can also cause problems. Best to decide on
>the best possible routing and install leaving just enough cable for drip
loops.
I did not intended proffer the idea that one
would purposely ADD coax to a feedline for
the purpose of reducing SWR. It is because
longer feedlines ADD losses that the SWR
appears to improve while in fact, the
effects of real SWR are being masked by
those losses. It was an observation of
fact, not a recommendation.
Bob . . .
________________________________________________________________________________
| From: | "kuffel(at)cyberport.net" <kuffel(at)cyberport.net> |
| Subject: | Re: ELT antenna performance |
After my first couple hundred aircraft searches up in
Alaska, and only two crashes myself, I've come to the strong
opinion a terrible ELT antenna inside the structure works
infinitely better than any exterior one removed in the
crash. Suggest builders consider a tailcone location for
fiberglass aircraft or somewhere, anywhere, in the cockpit
for metal ones.
It appears the 406 MHz ELTs will require one to use the
manufacturer's antenna to be legal so we probably can no
longer roll our own ELT dipoles or whips. But using a
simple ground plane in a glass tail or any handy metal
surface in the cockpit will do the job. Don't worry too
much about "seeing the sky". Orientation doesn't matter.
If you really need ELT operation you are unlikely to be
upright anyway.
Tom Kuffel
________________________________________________________________________________
| From: | "Noel Loveys" <noelloveys(at)yahoo.ca> |
| Subject: | Comm Antenna & SWR: More Information |
???? The VOR antenna whiskers are horizontally polarized
dipole with major lobes fore and aft with nulls off to the
sides. Further, dipole antennas require no ground plane.
VOR is not a transmitting antenna. The VOR transmitters are on the ground
and are also horizontally polarized. The receive lobes of the antennae are
part insignificant as aircraft do not approach the VOR sideways.
No such "null" exists fore and aft.
Experience as well as radio theory tells me is sure does exist on the tip of
horizontally polarized signals.
>Many large aircraft actually have antennae above and below the
>fuselage to allow communication with other aircraft as well as ground.
???? Antenna placement is largely a matter of separation
between the antennas for similar systems . . . and judicious
use of real estate. Once an airplane is airborne, relative
differences between top and bottom mounted antennas is
insignificant.
Then why do large Aircraft often have two com antennae? One on top,
Sometimes in the vert stab and one below. The reason for the two antennae
is because of shading of the signal to stations directly below the plane
(upper antenna) or shading of a other aircraft more or less directly above
the plane (Belly position antenna)
For some reason Bob I think we are off the same page again.
Noel
________________________________________________________________________________
| From: | "Robert L. Nuckolls, III" <nuckolls.bob(at)aeroelectric.com> |
| Subject: | Comm Antenna & SWR: More Information |
At 03:36 PM 1/28/2011, you wrote:
>
>
> b:???? The VOR antenna whiskers are horizontally polarized
> dipole with major lobes fore and aft with nulls off to the
> sides. Further, dipole antennas require no ground plane.
>
>VOR is not a transmitting antenna. The VOR transmitters are on the ground
>and are also horizontally polarized. The receive lobes of the antennae are
>part insignificant as aircraft do not approach the VOR sideways.
When you said:
"The important thing with com antennas is good omnidirectional ( all
directions ) coverage. A horizontally polarized antenna in a
tailcone, outside of having too small a ground plane, will have a
dead area in front of the plane and another one behind it. I can't
see how this can be considered good for airplanes heading into or
away from a control zone."
I didn't realize you were talking and an HF Comm trailing
wire. As soon as you mentioned horizontally polarized
antenna on the tailcone I thought you WERE talking about
a VOR antenna which IS commonly mounted on the tail and
IS horizontally polarized.
A further confusion point was your mention of a control
zone (always short range communications). I'm unaware of
any control zone services offered on any frequency where
an HF trailing wire would be the antenna of choice. The
most popular HF antenna for small airplanes produced at
Cessna was a wire that ran from the top of cabin to the
tip of the vertical fin and then out to one wing-tip.
Radiation pattern looked like a dying flower with badly
chewed petals. Here's a drawing from a kit I wrote for
a U17 HF installation way back when . . .
http://tinyurl.com/4eokmk8
> b:No such "null" exists fore and aft.
>
>Experience as well as radio theory tells me is sure does exist on the tip of
>horizontally polarized signals.
Agreed, we weren't talking about the same antenna . . .
>Then why do large Aircraft often have two com antennae? One on top,
>Sometimes in the vert stab and one below. The reason for the two antennae
>is because of shading of the signal to stations directly below the plane
>(upper antenna) or shading of a other aircraft more or less directly above
>the plane (Belly position antenna)
Because they have two radios and it's industry
practice to have one antenna for each radio and
to locate them as far as practical from each
other. "Shading" of a potential station right
over or below any given antenna is an exceedingly
rare event that lasts only seconds at the speeds
these airplanes fly.
Just got off the phone with a high-school buddy who's
been an ATP since about 1965. With 18K hours in
everything from DC-3's with dual ADF to Boeings
with cockpits full of glass, he tells me he's
never seen any difference in performance between
top and belly mounted antennas. He's a ham too
and speaks/understands radioeze . . .
>For some reason Bob I think we are off the same page again.
Correct. HF antennas on light aircraft are
EXCEEDINGLY inefficient, e-field antennas
and unless 'bent', they'll have strong nulls
off the ends irrespective of polarization. I thought
we were talking about aviation antennas likely to
be installed on airplanes flown by members of this List.
Bob . . .
________________________________________________________________________________
| From: | "Noel Loveys" <noelloveys(at)yahoo.ca> |
| Subject: | ELT antenna performance |
Thanks Dick... I was unaware there even was a millihertz. In English class
many snows ago we were told when it came to abbreviations, the rule was only
capitalize measurements which were peoples' names. Under that rule mHz
would be correct for either millihertz or megahertz or even gHz...gigahertz.
Noel
From: owner-aeroelectric-list-server(at)matronics.com
[mailto:owner-aeroelectric-list-server(at)matronics.com] On Behalf Of Richard
Tasker
Sent: January 28, 2011 12:45 PM
Subject: Re: AeroElectric-List: ELT antenna performance
Hey Bob, not to pick nits , but you are the example here after all... ;-)
mHz - millihertz
MHz - megahertz
Dick Tasker
Robert L. Nuckolls, III wrote:
When I first got into electronics as a profession,
I was working for a two-way radio company in Wichita.
We serviced a few systems in the 72 mHz band but
most were in the vicinity of 150 mHz and a few
were up about 450.
This was all vacuum tube stuff. The 450 mHz
equipment was at the upper fringe of what
was practical. It was harder to develop power,
losses in feedlines was higher, keeping
receiver sensitivity to less than 1 microvolt
was more demanding. All-in-all, higher
cost of ownership.
You'd think that customers would shy away from
this equipment. On the contrary. Antennas were
more efficient. Terrestrial noise was a small
influence. Signals behaved much better in the
confines of tall buildings. The cab companies
wouldn't have anything different. The police
wanted it but the FCC decreed that public
services will conduct business in the 150 mHz
band. 150 mHz was subject to much more multi-
path nulls and noise.
121.5 mHz was picked for the first ELTs
because it was a frequency already serviced
by aviation communication services. Same
with 243 albeit military.
________________________________________________________________________________
| From: | "Noel Loveys" <noelloveys(at)yahoo.ca> |
| Subject: | ELT antenna performance |
Don't feel in the slightest bad Bob... I'm guilty too.
Noel
-----Original Message-----
From: owner-aeroelectric-list-server(at)matronics.com
[mailto:owner-aeroelectric-list-server(at)matronics.com] On Behalf Of Robert L.
Nuckolls, III
Sent: January 28, 2011 1:47 PM
Subject: Re: AeroElectric-List: ELT antenna performance
At 11:15 AM 1/28/2011, you wrote:
>Hey Bob, not to pick nits , but you are the example here after all... ;-)
>
>mHz - millihertz
>
>MHz - megahertz
>
>Dick Tasker
You're quite correct. Unfortunately, when trying
to bang out a timely but extensive reply, I don't
have the luxury of coming back to edit it tomorrow
to attempt a 99% clean posting.
When I go back and read my past postings, it's
not unusual to get whacked by spelling/semantics
issues. I'll just have to beg the Lists indulgence.
That doesn't mean I don't want to hear from
folks when I've stubbed my toe. Just be forewarned
that in spite of your most honorable efforts, my
head will probably continue to run out in front of
fingers on the keyboard.
Thanks for the heads-up!
Bob . . .
________________________________________________________________________________
| From: | Mike Welch <mdnanwelch7(at)hotmail.com> |
| Subject: | ELT antenna performance |
> Don't feel in the slightest bad Bob... I'm guilty too.
>
> Noel
> >mHz - millihertz
> >
> >MHz - megahertz
> >
> >Dick Tasker
Fortunately=2C I can honstly sya=2C I nver make any tpos. : )
Mik e
________________________________________________________________________________
| From: | Bill Watson <Mauledriver(at)nc.rr.com> |
OK, that's the second time I've heard about this stuff in 24 hours...
so, if you want an entertaining survey of modern materials (including a
demonstration of graphene production) check this out:
http://www.pbs.org/wgbh/nova/tech/making-stuff.html
I expected less from this NOVA series but was entertained and informed
throughout the first 2 shows.
Bill Watson
RV10
On 1/26/2011 11:29 PM, Speedy11(at)aol.com wrote:
> Bob,
> I'm sure you're familiar with this, but this blog is the first I've
> heard of it.
> More info is on the CAFE Blog at http://blog.cafefoundation.org/?p=2439.
> Stan Sutterfield
>
>
> Thin, Light, Strong, and Energy Dense
>
> by Dean Sigler on 01/07/2011
>
> 2010s Nobel Prize in Physics
> <http://nobelprize.org/nobel_prizes/physics/laureates/2010/press.html>went
> to Andre Geim and Konstantin Novoselov, who extracted graphene from a
> piece of graphite when they stuck a piece of adhesive tape to it and
> peeled away a single atom-thick layer of the thinnest, strongest
> material in the world.
>
> The Nobel Prize web site explains other remarkable properties of this
> new material. As a conductor of electricity it performs as well as
> copper. As a conductor of heat it outperforms all other known
> materials. It is almost completely transparent, yet so dense that not
> even helium, the smallest gas atom, can pass through it. Carbon, the
> basis of all known life on earth, has surprised us once again.
>
> When mixed into plastics, graphene can turn them into conductors of
> electricity while making them more heat resistant and mechanically robust.
>
> /Over 28,000 square feet per gram for a single layer of the material
> or about the size of a football field/
>
> *
>
> *
________________________________________________________________________________
| From: | "John F. Herminghaus" <catignano(at)teletu.it> |
Bob,
I have become aware that BNC connectors have at least two flavors: 50
and 75 ohms. Not being sure which impedance my connectors have I
measured the SWR for my com and vor antennas. The com was 1.2 to 3.1
with the 3.1 at 118.0 mhz. Above 119 mhz it was below 2. The vor was
between 1.1 and 1.9 over the full frequency range. According to your
book, they should be OK. But what about GPS, DME and transponder
antennas. Is the impedance of the connector important? In other words
should I go to the trouble of making sure all connectors are 50 ohms?
John Herminghaus
________________________________________________________________________________
| From: | "Robert L. Nuckolls, III" <nuckolls.bob(at)aeroelectric.com> |
| Subject: | Re: BNC connectors |
At 12:52 AM 1/29/2011, you wrote:
>Bob,
>
>I have become aware that BNC connectors have at least two flavors:
>50 and 75 ohms. Not being sure which impedance my connectors have I
>measured the SWR for my com and vor antennas. The com was 1.2 to
>3.1 with the 3.1 at 118.0 mhz. Above 119 mhz it was below 2. The
>vor was between 1.1 and 1.9 over the full frequency
>range. According to your book, they should be OK. But what about
>GPS, DME and transponder antennas. Is the impedance of the
>connector important? In other words should I go to the trouble of
>making sure all connectors are 50 ohms?
The connectors are "50 ohm" because they
have dimensions conducive to installation
on a piece of 50 ohm coax. If your connector
fits on the coax, then it's the right
connector.
Bob . . .
________________________________________________________________________________
| From: | "John F. Herminghaus" <catignano(at)teletu.it> |
| Subject: | Re: BNC connectors |
Thanks a lot. That's what I suspected and hoped to hear. You saved me
a lot ot trouble
John
On 29.01.2011 06:15, Robert L. Nuckolls, III wrote:
> At 12:52 AM 1/29/2011, you wrote:
>> Bob,
>>
>> I have become aware that BNC connectors have at least two flavors: 50
>> and 75 ohms. Not being sure which impedance my connectors have I
>> measured the SWR for my com and vor antennas. The com was 1.2 to 3.1
>> with the 3.1 at 118.0 mhz. Above 119 mhz it was below 2. The vor
>> was between 1.1 and 1.9 over the full frequency range. According to
>> your book, they should be OK. But what about GPS, DME and
>> transponder antennas. Is the impedance of the connector important?
>> In other words should I go to the trouble of making sure all
>> connectors are 50 ohms?
>
> The connectors are "50 ohm" because they
> have dimensions conducive to installation
> on a piece of 50 ohm coax. If your connector
> fits on the coax, then it's the right
> connector.
>
> Bob . . .
>
> *
>
>
> *
________________________________________________________________________________
| Subject: | Re: Questions about the 9005 Low Voltage Module |
| From: | Jared Yates <email(at)jaredyates.com> |
Update- my 9005 unit is working now. I replaced the reference diode with ano
ther and all is well. I must have damaged the first one somehow. If anyone e
lse i planning on making one of these, let me know. I have lots of extra par
ts from the digikey order minimums, and a functioning test rig that I can se
nd you for a few bucks in shipping.
On Jan 4, 2011, at 10:11, "Robert L. Nuckolls, III" <nuckolls.bob@aeroelectr
ic.com> wrote:
> At 09:28 PM 1/3/2011, you wrote:
>> That's great information, thank you for your help! I found the Digikey i
nvoice and I think I might have ordered the wrong part.
>>
>> The national part is the Digikey LM285Z-2.5-ND
>> http://www.national.com/ds/LM/LM185-2.5.pdf
>>
>> The one that I ordered is made by ON Semiconductor, Digikey LM285Z-2.5GOS
-ND.
>> http://www.onsemi.com/pub_link/Collateral/LM285-D.PDF
>>
>
> I don't think so. The LM series devices are National
> Semiconductor originations. All competing manufacturers
> have to put out a drop in duplicate of the part.
>
> If the voltage at U107-3 had been zero or identical
> to an adjacent pin, then I would suspect a solder
> splash or an ECB defect often called a 'cat hair'.
> The fact that your measurement is unique and way out
> of whack for what the LM285 should present suggests
> that neither event is in force. You might check
> markings or color code for the R104 . . . make sure
> it.s a 4.7K and not something higher. Also re-flow
> the solder joins on R104. It's extremely rare that a
> new part is bad out of the box so if the LM285 is
> not installed wrong, we need to explore other possible
> causes for U107-3 voltage not to be 2.50 volts.
>
>
> Bob . . .
>
>
>
==========================
=========
==========================
=========
==========================
=========
==========================
=========
>
________________________________________________________________________________
| From: | "Robert L. Nuckolls, III" <nuckolls.bob(at)aeroelectric.com> |
| Subject: | Re: Questions about the 9005 Low Voltage Module |
At 09:33 AM 1/29/2011, you wrote:
>Update- my 9005 unit is working now. I replaced the reference diode
>with another and all is well. I must have damaged the first one
>somehow. If anyone else i planning on making one of these, let me
>know. I have lots of extra parts from the digikey order minimums,
>and a functioning test rig that I can send you for a few bucks in shipping.
Congratulations! You're now much further down
the path of a very steep learning curve. I hope
this experience encourages you to continue expanding
your horizons.
I've had an increased interest in the 9005 . . . in fact,
I had to order more bare boards. I'd planned to phase
it out entirely but it's a good starting point for
individuals who want to put their toes in the
electronic pond.
As you've discovered, the water only seems cold . . .
Bob . . .
________________________________________________________________________________
| From: | paul wilson <pwmac(at)sisna.com> |
| Subject: | Re: OT-potting with RTV silicone |
Correct and that brand uses an acid .
Having said that you can still buy RTV that contaons no acid.
The no acid type is what the Kitfox guys use to bond the fiberglass
tank to the Al spar.
Avoid the acetic acid mentioned on the label.
All use moisture as the curing catalyst.
PaulW
=====
At 06:06 AM 1/29/2011, Robert L. Nuckolls, III wrote:
>The garden variety RTV's smell like
> vinegar . .
________________________________________________________________________________
| Subject: | Re: ELT antenna performance |
| From: | Bill Boyd <sportav8r(at)gmail.com> |
Millihertz antennas are impractically long. At least, the resonant ones
are. Your mileage won't vary on this one.
-Bill B
On Fri, Jan 28, 2011 at 7:15 PM, Noel Loveys wrote:
> Thanks Dick... I was unaware there even was a millihertz. In English cla
ss
> many snows ago we were told when it came to abbreviations, the rule was o
nly
> capitalize measurements which were peoples=92 names. Under that rule mH
z
> would be correct for either millihertz or megahertz or even gHz...gigaher
tz.
>
>
> Noel
>
>
> *From:* owner-aeroelectric-list-server(at)matronics.com [mailto:
> owner-aeroelectric-list-server(at)matronics.com] *On Behalf Of *Richard
> Tasker
> *Sent:* January 28, 2011 12:45 PM
>
> *To:* aeroelectric-list(at)matronics.com
> *Subject:* Re: AeroElectric-List: ELT antenna performance
>
>
> Hey Bob, not to pick nits , but you are the example here after all... ;-
)
>
>
> mHz - millihertz
>
> MHz - megahertz
>
> Dick Tasker
>
> Robert L. Nuckolls, III wrote:
>
>
>
> When I first got into electronics as a profession,
> I was working for a two-way radio company in Wichita.
> We serviced a few systems in the 72 mHz band but
> most were in the vicinity of 150 mHz and a few
> were up about 450.
>
> This was all vacuum tube stuff. The 450 mHz
> equipment was at the upper fringe of what
> was practical. It was harder to develop power,
> losses in feedlines was higher, keeping
> receiver sensitivity to less than 1 microvolt
> was more demanding. All-in-all, higher
> cost of ownership.
>
> You'd think that customers would shy away from
> this equipment. On the contrary. Antennas were
> more efficient. Terrestrial noise was a small
> influence. Signals behaved much better in the
> confines of tall buildings. The cab companies
> wouldn't have anything different. The police
> wanted it but the FCC decreed that public
> services will conduct business in the 150 mHz
> band. 150 mHz was subject to much more multi-
> path nulls and noise.
>
> 121.5 mHz was picked for the first ELTs
> because it was a frequency already serviced
> by aviation communication services. Same
> with 243 albeit military.
>
> *
>
===========
>
===========
===========
===========
>
> *
>
>
________________________________________________________________________________
| From: | "kuffel(at)cyberport.net" <kuffel(at)cyberport.net> |
| Subject: | Comm Antenna & SWR: More Information |
Noel said:
<< The new units are programmed to a specific aircraft.
The first problem I see with this is as soon as a signal is
received it can be identified as a single seat something or
the other and not all the resources that could be put in the
field will be used. This is selective response and I for
one am against it. >>
Different response is news to me. "Don't know how they do
it Outside" but up in Alaska my direct experience was the
effort was the same for one or multiple people down. Now
when two congressmen go down, including the House Majority
Leader, then you get extra resources (can you spell SR-71?).
Tom Kuffel
________________________________________________________________________________
| Subject: | Conduit and Abrasion |
| From: | "Andy Turner" <aturner(at)clarion.edu> |
Well, this is one of those "making decisions when working late at night and then
waking up the next morning and feeling bad about it" situations. I ran Van's
3/4" conduit under the baggage compartment of my RV-10, and then riveted floors
into place. I fabricated aluminum supports which attach to the floor ribs as
shown below. Due to the corrugations, you have to open up the hole to the point
that the conduit rattles around in there. So I put some RTV on the conduit
and support (I know, E6000 would have been better), and buttoned everything up.
Almost immediately had visions of the support wearing a hole in the conduit
and shorting out the battery main feed. On the right side I did it right, with
snap bushings or grommet protecting conduit from aluminum. Question is, is the
left side setup shown below a short waiting to happen? How resistant is this
conduit to abrasion? The aluminum support is 0.32, well polished.
--------
Andy Turner
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=328926#328926
________________________________________________________________________________
| From: | "Robert L. Nuckolls, III" <nuckolls.bob(at)aeroelectric.com> |
| Subject: | Re: Conduit and Abrasion |
>On the right side I did it right, with snap bushings or grommet
>protecting conduit from aluminum. Question is, is the left side
>setup shown below a short waiting to happen? How resistant is this
>conduit to abrasion? The aluminum support is 0.32, well polished.
Legacy design practice avoids having any material
carrying any commodity free to "ride loose" on the
edge of a sheet. Consider caterpillar grommets for
your problem holes.
http://tinyurl.com/4kj3ak4
http://www.surplussales.com/rubber-plastic/plastic-2.html
http://www.aircraftspruce.com/catalog/appages/grommetedging.php
There are many other sources for similar products.
These will soften the edges while widening them
to the extent that they do not produce wearing
pressure on the conduit or wires.
The cool thing is that it can be added over an
existing conduit installation.
Bob . . .
________________________________________________________________________________
| From: | Jeff Page <jpx(at)qenesis.com> |
| Subject: | Re: OT-potting with RTV silicone |
You can buy silicone without acetic acid at the pet store - used for
sealing aquariums. I haven't tried it for potting though.
Jeff Page
Dream Aircraft Tundra #10
________________________________________________________________________________
| From: | "Robert L. Nuckolls, III" <nuckolls.bob(at)aeroelectric.com> |
| Subject: | Re: OT-potting with RTV silicone |
At 10:30 AM 1/30/2011, you wrote:
>
>You can buy silicone without acetic acid at the pet store - used for
>sealing aquariums. I haven't tried it for potting though.
Thank you! I'd forgotten about that. I think the
same grade of RTV is approved for situations that
come into contact with food.
I'm pretty sure this stuff would do the job if applied
in several layers of 1/4" or less and allowed to cure
before more is added.
Bob . . .
////
(o o)
===========o00o=(_)=o00o========
< Go ahead, make my day . . . >
< show me where I'm wrong. >
================================
________________________________________________________________________________
| From: | "jonlaury" <jonlaury(at)impulse.net> |
I used one of these http://www.ledlightsworld.com/12v-inline-led-dimmer-switch-with-rotary-knob-2a-24w-p-191.html to control some LED lights in my panel by cannibalizing the innards for a panel mount w/knob.
Could this also be used to control incandescent lamps in my rocker switches?
Thanks,
John
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=329010#329010
________________________________________________________________________________
| From: | "Robert L. Nuckolls, III" <nuckolls.bob(at)aeroelectric.com> |
At 03:04 PM 1/30/2011, you wrote:
>
>I used one of these
>http://www.ledlightsworld.com/12v-inline-led-dimmer-switch-with-rotary-knob-2a-24w-p-191.html
>to control some LED lights in my panel by cannibalizing the innards
>for a panel mount w/knob.
>Could this also be used to control incandescent lamps in my rocker switches?
Sure. Both LED and incandescent lamps are friendly
to duty-cycle dimming. It's illumination systems with
ELECTRONICS between the ship's power and the light
emitting devices that are problematic. This includes
but is not limited to flourescent and electro-luminescent
lamps.
Bob . . .
////
(o o)
===========o00o=(_)=o00o========
< Go ahead, make my day . . . >
< show me where I'm wrong. >
================================
________________________________________________________________________________
| From: | Bob Falstad <bobair(at)me.com> |
| Subject: | Comm Antenna & SWR: Grounding Issue |
Bob N., et al,
I have run a bunch of additional tests of my antennas in various configurations
to see what effect they had on VSWR readings. The raw data and VSWR results
are pretty variable (to my eyes) and not very encouraging.
But my immediate issue is the one that Bob N. focused on shortly after my original
post -- the quality of the ground between my antenna base and my ground plane.
At the time I did the original tests, it tested out at ~0.1 Ohms on my digital
VOM.
But I dug out the four-wire ohmmeter that I build years ago based on Bob N's directions
in the AeroElectric Connection and soldered in a fresh "D Cell" battery.
The meters (especially the voltmeter) fluctuated quite rapidly and over quite
a range so I'm not sure my data are accurate (although it did come close
to the calculated resistance of a hunk of 18 AWG wire that I used to check the
four-wire ohmmeter for accuracy).
As best I can tell, the resistance between my antenna mounting screws and the ground
plane are in the 250 milli-Ohm range. This seems to be way too high. Is
it? I believe you said that resistance should be in the very low milli-Ohm
or even micro-Ohm range.
I've got one of your newer low resistance testers on order and as soon as I get
it, I'll measure the resistance again.
I'll probably just have to pull the ground plane and re-do the mechanical mounting
again and hope I get a lower resistance.
Would it make sense to get some conductive epoxy and bond a ground strap from the
antenna base to the ground plane? I know soldering copper to aluminum doesn't
work and corrodes almost immediately. I've seen some silver-filled epoxies
rated as low as 0.001 Ohm-cm but that stuff is expensive. Could I solder a
small ground strap to the antenna's metal base without damaging the antenna?
I've got room in the hole for the BNC connector to run a small ground strap up
from the antenna base to a ring terminal that I could clamp under one of the
mounting screws. Would conductive gel under the hardware help?
Since I've got a glass skin between the antenna base and the washer stack that
leads to the ground plane, I didn't "brighten" the underside of the ground plane
-- just the top under each of the four machine screws. I'm thinking if I brightened
up both sides of the ground plane, there might be some improvement because
of the additional contact between the hardware stack, the machine screws
and the underside of the ground plane.
All comments and thoughts are welcome.
Best regards,
Bob Falstad
GlaStar N248BF
________________________________________________________________________________
| From: | Werner Schneider <glastar(at)gmx.net> |
| Subject: | Re: Comm Antenna & SWR: Grounding Issue |
Bob,
I would pull the foam on a 1/2 radius out, fill them with resin/filler
mix like the other cage holes, then drill them out to add a metal sleeve
over the screws, that one would touch the base of your antenna and the
groundplane (probably on two holes already enough), make sure the
sleeves a re a tad longer then the fiber ull thickness. Then mount the
antenna again (tarque screws)and use some rtv around the corner to seal.
That is what I did with my belly antenna and it works fine.
br Werner
On 31.01.2011 03:58, Bob Falstad wrote:
>
> I'll probably just have to pull the ground plane and re-do the mechanical mounting
again and hope I get a lower resistance.
>
> Would it make sense to get some conductive epoxy and bond a ground strap from
the antenna base to the ground plane? I know soldering copper to aluminum doesn't
work and corrodes almost immediately. I've seen some silver-filled epoxies
rated as low as 0.001 Ohm-cm but that stuff is expensive. Could I solder
a small ground strap to the antenna's metal base without damaging the antenna?
I've got room in the hole for the BNC connector to run a small ground strap
up from the antenna base to a ring terminal that I could clamp under one of the
mounting screws. Would conductive gel under the hardware help?
>
> Since I've got a glass skin between the antenna base and the washer stack that
leads to the ground plane, I didn't "brighten" the underside of the ground plane
-- just the top under each of the four machine screws. I'm thinking if I
brightened up both sides of the ground plane, there might be some improvement
because of the additional contact between the hardware stack, the machine screws
and the underside of the ground plane.
>
________________________________________________________________________________
| From: | "kuffel(at)cyberport.net" <kuffel(at)cyberport.net> |
| Subject: | Re: Comm Antenna & SWR: Grounding Issue |
Bob,
Another issue you might want to keep in mind is the
characteristics of the surface under a belly mounted
antenna. Rebar in concrete or conductive soil near the tip
(as opposed to the base) of a whip antenna can screw up
performance until you are in the air.
A reverse example of this is up in Alaska (again) the
permafrost is very non-conductive. You could spread out an
HF antenna on the ground, tune it exactly to frequency and
raise it up 50 feet in the air with no change in
performance. Or more related to your possible situation,
Seattle's soggy soil is so conductive you can mount a
vertical antenna in the ground and have it perform well
without any of the normally required ground radial wires.
Tom Kuffel
________________________________________________________________________________
| From: | Jan de Jong <jan_de_jong(at)casema.nl> |
Check out "Shorai".
New light weight Japanese LiFePO4 battery with quite enthousiastic
motorcyclist customers.
Works well enough at low temperatures.
Max. charging current 18A (no external shunts). Higher ratings coming.
Has a 5 pin plug that I suspect may give access to the 4 cells.
For our use I might want to monitor max. cell voltage to see <4V or
interrupt charging.
Cheers,
Jan de Jong
________________________________________________________________________________
| Subject: | Inst GND Bus and 18 AWG wire |
| From: | "rvg8tor" <rvg8tor(at)comcast.net> |
I bought the AEC Instrument ground bus, which is a Dsub 37 pin connector. In looking
at my instrument panel items the radios have 18 AWG wires for the power
and grounds.
The Dsub standard density pins only take up to a 20 AWG wires, so how to deal with
the 18 AWG wires. should I solder a Y of 20AWG to the 18 AWG wire to go into
the ground bus or should I just run the wires all the way to the forest of
tabs on the firewall. One fella on another site said this would work but you
can't guarantee the flow of power would evenly split down the "Y". The radio
is on a 10 amp breaker to protect the 18 AWG wire but how does this work if you
slit to smaller wires, to share the load so to speak.
It is a metal airplane, the kit instructions have you bolt studs to the cross member
behind the firewall, I have the ground tab bolted there but insulated from
the airframe, there are five 20 AWG wires that run to the forest of tabs.
I must say having this ground bus right where the instrument are is kind of nice.
I assume it would be bad grounding practice to just bolt these 18 AWG wires to
the cross beam behind the panel?
Thanks for any help.
--------
Mike "Nemo" Elliott
RV-8A QB (Fuselage)
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=329269#329269
________________________________________________________________________________
| From: | "Robert L. Nuckolls, III" <nuckolls.bob(at)aeroelectric.com> |
| Subject: | Re: Inst GND Bus and 18 AWG wire |
At 11:31 PM 2/1/2011, you wrote:
>
>I bought the AEC Instrument ground bus, which is a Dsub 37 pin
>connector. In looking at my instrument panel items the radios have
>18 AWG wires for the power and grounds.
>The Dsub standard density pins only take up to a 20 AWG wires, so
>how to deal with the 18 AWG wires. should I solder a Y of 20AWG to
>the 18 AWG wire to go into the ground bus or should I just run the
>wires all the way to the forest of tabs on the firewall. One fella
>on another site said this would work but you can't guarantee the
>flow of power would evenly split down the "Y". The radio is on a 10
>amp breaker to protect the 18 AWG wire but how does this work if you
>slit to smaller wires, to share the load so to speak.
Peel out enough strands from the end of the 18AWG
wire to allow remaining strands to fit into the
20AWG pin.
>I assume it would be bad grounding practice to just bolt these 18
>AWG wires to the cross beam behind the panel?
No, but neither is is bat practice to trim
the wire down until it fits the pin.
Bob . . .
________________________________________________________________________________
| From: | "Robert L. Nuckolls, III" <nuckolls.bob(at)aeroelectric.com> |
| Subject: | Wrong pins shipped in 37-Pin Panel Ground Bus |
It has come to my attention that a number of
37-pin ground bus kits were shipped with female
as opposed to male d-sub pins. I had a note from
one builder . . . I also found some kits in inventory
that were incorrectly pinned
If anyone finds that they have the wrong pins, drop
me a note. I'll forward a correct set of pin along
with a pre-addressed and stamped envelope for
returning the incorrect pins.
I guess that's what I get for playing around in
the shop when I probably should be in bed!
Bob . . .
________________________________________________________________________________
| Subject: | wire squash connections |
| From: | "Bob Marshall" <marshall6916(at)sbcglobal.net> |
I plan to use p-mags and the installation instructions show the connections made
to the controller are simply striped wire leads placed under screws. Since
this is under the cowl, I was hoping that there was a better way. Is there a
crimped terminal that could be used along with some heat shrink tubing?
My first post here though I have been reading for a while. Thanks,
Bob
I would post a photo but I cannot figure how to do it.
--------
RV-6A construction resumed. Planning electrical and building wing.
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=329292#329292
________________________________________________________________________________
| Subject: | Re: wire squash connections |
| From: | Robert Borger <rlborger(at)mac.com> |
Bob,
Interesting. I plan to put a pair of P-Mags on the Lycoming for my Toot.
Rather than bare wires under a screw, I'd think about crimping a suitably sized
ring terminal onto the wire with proper shrink tube and placing the ring under
the screw along with a lock washer.
Others, please chime in if there's an error in my thinking as it's info I'll eventually
need.
Thanks,
Bob Borger
Europa Kit #A221 N914XL, XS Tri-Gear, Intercooled 914, Airmaster C/S Prop
http://www.europaowners.org/forums/gallery2.php?g2_itemId=60232
http://www.biplaneforumgallery.com/index.php?cat=10046
Europa Flying!
3705 Lynchburg Dr.
Corinth, TX 76208
Home: 940-497-2123
Cel: 817-992-1117
On Feb 2, 2011, at 8:58, Bob Marshall wrote:
>
> I plan to use p-mags and the installation instructions show the connections made
to the controller are simply striped wire leads placed under screws. Since
this is under the cowl, I was hoping that there was a better way. Is there
a crimped terminal that could be used along with some heat shrink tubing?
> My first post here though I have been reading for a while. Thanks,
> Bob
> I would post a photo but I cannot figure how to do it.
>
> --------
> RV-6A construction resumed. Planning electrical and building wing.
>
>
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=329292#329292
>
>
>
>
>
>
>
>
>
>
________________________________________________________________________________
| From: | "Robert L. Nuckolls, III" <nuckolls.bob(at)aeroelectric.com> |
| Subject: | Re: wire squash connections |
At 09:58 AM 2/2/2011, you wrote:
>
>
>I plan to use p-mags and the installation instructions show the
>connections made to the controller are simply striped wire leads
>placed under screws. Since this is under the cowl, I was hoping
>that there was a better way. Is there a crimped terminal that could
>be used along with some heat shrink tubing?
Yeah, my biggest disappointment with that product.
Their service experience with that configuration must
be okay . . . that's what they've used since day one.
Crimping the appendage of some sort of terminal in
those connections might be a bit better than just
crimping the wire . . . but not much.
My best suggestion is to strip leads (20AWG)
to proper length and then 'comb' them such
that they all lay parallel to each other. Then
connect with as much torque on the screws as
you dare.
Try to support the bundles within a few inches
of where they connect with the ignition modules.
Bob . . .
________________________________________________________________________________
| From: | "Robert L. Nuckolls, III" <nuckolls.bob(at)aeroelectric.com> |
| Subject: | Re: wire squash connections |
At 10:26 AM 2/2/2011, you wrote:
>
>Bob,
>
>Interesting. I plan to put a pair of P-Mags on the Lycoming for my Toot.
>
>Rather than bare wires under a screw, I'd think about crimping a
>suitably sized ring terminal onto the wire with proper shrink tube
>and placing the ring under the screw along with a lock washer.
>
>Others, please chime in if there's an error in my thinking as it's
>info I'll eventually need.
Just so we're all on the same page . . .
The twist-n-squash terminal strips featured in this
thread are probably the best there is for taking
wires to etched circuit boards with convenience,
minimum cost and reliability . . . UNDER CERTAIN
CONDITIONS. Here's one example of the technology:
Emacs!
Here's one of my favorite $100 data acquisition modules that
uses the same terminal strip.
Emacs!
Note that the bared end of a wire is NOT captured by
a head of the mash-screw . . .
Emacs!
But by the END of the mash-screw. Further, there is a buffer
strip between the wire strands and the end of the screw. If one
REALLY needs to use a twist-n-squash technology, this is one of
the best.
Legacy design goals for aviation (and other disciplines)
have adopted processes that offer gas-tightness in the
metallic joints of the current carrying pathway along
with wire support immediately adjacent to the gas-tight
joint that prevents failure of the wire under vibration.
Without getting in too much of a dither about new design
goals, I think the best application of this process calls
for parallel strands of wire pressed into the lower
concave surface of the cavity with force from above
offered by the screw. Then supply bundle support within
a couple inches of the squash-joints.
Note that is NOT what I did on this particular example . . .
but then this DAM isn't expected to be in place and
functioning after what we hope is decades of otherwise
unattended service.
Bob . . .
________________________________________________________________________________
| Subject: | Re: wire squash connections |
| From: | Robert Borger <rlborger(at)mac.com> |
Bob,
Oh, OK. Now I see (literally) what was being talked about.
Not the "wrap the wire around the screw and tighten" kind of under screw.
Would crimping a D-Sub female connector pin onto the end of the wire and adding
a couple layers of shrink tube over the junction for some stress relief provide
a better item to be pressed under the screw? Again assuming you would provide
some wire support close to the box.
Thanks,
Bob
On Feb 2, 2011, at 17:25, Robert L. Nuckolls, III wrote:
> At 10:26 AM 2/2/2011, you wrote:
>>
>> Bob,
>>
>> Interesting. I plan to put a pair of P-Mags on the Lycoming for my Toot.
>>
>> Rather than bare wires under a screw, I'd think about crimping a suitably sized
ring terminal onto the wire with proper shrink tube and placing the ring
under the screw along with a lock washer.
>>
>> Others, please chime in if there's an error in my thinking as it's info I'll
eventually need.
>
> Just so we're all on the same page . . .
>
> The twist-n-squash terminal strips featured in this
> thread are probably the best there is for taking
> wires to etched circuit boards with convenience,
> minimum cost and reliability . . . UNDER CERTAIN
> CONDITIONS. Here's one example of the technology:
>
> <1e81a25b.jpg>
>
> Here's one of my favorite $100 data acquisition modules that
> uses the same terminal strip.
>
> <1e81a2d8.jpg>
>
> Note that the bared end of a wire is NOT captured by
> a head of the mash-screw . . .
>
> <1e81a345.jpg>
>
> But by the END of the mash-screw. Further, there is a buffer
> strip between the wire strands and the end of the screw. If one
> REALLY needs to use a twist-n-squash technology, this is one of
> the best.
>
> Legacy design goals for aviation (and other disciplines)
> have adopted processes that offer gas-tightness in the
> metallic joints of the current carrying pathway along
> with wire support immediately adjacent to the gas-tight
> joint that prevents failure of the wire under vibration.
>
> Without getting in too much of a dither about new design
> goals, I think the best application of this process calls
> for parallel strands of wire pressed into the lower
> concave surface of the cavity with force from above
> offered by the screw. Then supply bundle support within
> a couple inches of the squash-joints.
>
> Note that is NOT what I did on this particular example . . .
> but then this DAM isn't expected to be in place and
> functioning after what we hope is decades of otherwise
> unattended service.
>
> Bob . . .
>
________________________________________________________________________________
| From: | "Robert L. Nuckolls, III" <nuckolls.bob(at)aeroelectric.com> |
| Subject: | When is a 'ground' not a 'ground' |
At 09:58 PM 1/30/2011, you wrote:
Bob N., et al,
I have run a bunch of additional tests of my antennas in various
configurations to see what effect they had on VSWR readings. The raw
data and VSWR results are pretty variable (to my eyes) and not very
encouraging.
But my immediate issue is the one that Bob N. focused on shortly
after my original post -- the quality of the ground between my
antenna base and my ground plane. At the time I did the original
tests, it tested out at ~0.1 Ohms on my digital VOM.
But I dug out the four-wire ohmmeter that I build years ago based on
Bob N's directions in the AeroElectric Connection and soldered in a
fresh "D Cell" battery. The meters (especially the voltmeter)
fluctuated quite rapidly and over quite a range so I'm not sure my
data are accurate (although it did come close to the calculated
resistance of a hunk of 18 AWG wire that I used to check the
four-wire ohmmeter for accuracy).
While based on solid physics, THAT test tool was a
hurry-up jury-rig that helped me make some good
measurements in the field with locally acquired
materials. It had no constant current generator
and therefore taxed the operator to visually integrate
voltage/current readings to deuce resistance value
with something like 10% accuracy. The test current
was not REAL stable. Further, using 'shorted'
Adapter I'm offering from the website. I mention
this because one should approach low-ohms measurements
with some degree of caution. Be aware that SOME
devices may not tolerate so high a test current.
While exploring 'hardware' it's not a concern but
be cautious with the measurement of electro-whizzies.
As best I can tell, the resistance between my antenna mounting screws
and the ground plane are in the 250 milli-Ohm range. This seems to
be way too high. Is it? I believe you said that resistance should
be in the very low milli-Ohm or even micro-Ohm range.
Yes . . . and forgive me, I need to interject another
simple but significant idea into this discussion.
Using the DC ohmmeter to evaluate the metallic
connection between two components is a legacy
standard examination of the joints between ground
straps and the airframe. These investigations are
concerned with predicting performance of a high
current ground like a cranking battery or a bond-
strap for lightning protection.
The DC measurement offers SOME insight for grounding
antennas when the base of the antenna is brought
into forceful proximity with the belly skins
and structure of an airplane. But as soon
as we insert a gap between the base and ground plane,
the reliability of a DC resistance begins to fail
for predicting performance of the joint at very high
radio frequencies.
For example, We could set the comm antenna up on a
22" tall pedestal of copper tube. The DC resistance
of that tube may still be in the low milliohms but
because its LENGTH is exactly 1/4-wave at 126 Mhz,
the ground IMPEDANCE at the top of pedestal would
be THOUSANDS of ohms.
This is why I made the statement earlier this
week that the "quality" of your antenna grounding
was more of an "art" borne of experience and
command of simple-ideas than a matter of measuring
milliohms from one point to another.
I've got one of your newer low resistance testers on order and as
soon as I get it, I'll measure the resistance again.
I'll probably just have to pull the ground plane and re-do the
mechanical mounting again and hope I get a lower resistance.
As stated above, a HIGH DC resistance reading in a
stack up of metallic components is reason for further
investigation, a LOW reading is not necessarily
golden at radio frequencies.
Would it make sense to get some conductive epoxy and bond a ground
strap from the antenna base to the ground plane? I know soldering
copper to aluminum doesn't work and corrodes almost
immediately. I've seen some silver-filled epoxies rated as low as
0.001 Ohm-cm but that stuff is expensive. Could I solder a small
ground strap to the antenna's metal base without damaging the
antenna? I've got room in the hole for the BNC connector to run a
small ground strap up from the antenna base to a ring terminal that I
could clamp under one of the mounting screws. Would conductive gel
under the hardware help?
Yeaaahhh . . . maybe . . . but . . . As a
a practical matter, the TC aircraft industry
has learned to minimize process sensitive
materials that involve pastes, goops, glues, goos
and extraordinary technician's skills.
In addition to the demands of skill and process
to maximize performance, these materials tend
to have a poor service life. They're not even
close to both performance and longevity of a
(1) a single piece of metal or (2)
multiple pieces welded together or (3) pieces
bolted together with enough force to achieve and
maintain gas-tightness between the pieces in
spite the variables of temperature, moisture,
flexure and time.
Since I've got a glass skin between the antenna base and the washer
stack that leads to the ground plane, I didn't "brighten" the
underside of the ground plane -- just the top under each of the four
machine screws. I'm thinking if I brightened up both sides of the
ground plane, there might be some improvement because of the
additional contact between the hardware stack, the machine screws and
the underside of the ground plane.
Okay, if it were my airplane . . .
I'd ditch the aluminum ground plane. Get a piece
of brass sheet, .032 to .040 thick and 1" larger
than extremes of antenna base on all four sides.
Drill #10 close clearance holes and BNC clearance
holes to match antenna base and exactly centered on
the sheet.
Cut 4 spacers from brass. 3/8 to 1/2-inch diameter and
drilled for #10 close clearance. Cut and drill
these on a lathe. By definition, the end of a cylinder
faced in a lathe is perfectly perpendicular to
the axis. Also, the thru holes will be exactly
centered. Make them 1/32" longer than the distance
it takes to come through the thickness of the
composite belly material.
Use 63/37 solder to 'tin' both ends of the spacers
and the area around the bottom side of the brass plate.
Wipe the 'tinning' off with a dry rag while still
hot . . . you don't want any visible 'thickness'
of solder. Bolt the spacers to the plate and solder
to the plate. Tighten the bolts while the solder is
molten to make sure spacers are flat to the plate.
You need just enough solder to form a small fillet
around the spacer.
When you're done, you'll have a one-piece of metal
that can be installed in the airplane. The four
spacer holes need to be enlarged to about 1/8"
larger radius than the spacer diameter. Put some
10-32 screws in the holes, nuts against the plate.
Tape over the bottoms of the four spacer holes in
the belly skin. Fill the holes about 1/2 with
catalyzed resin. Paint the underside of the plate
with catalyzed resin. Press the assembly into the
final resting place and fixture with sand bags,
shot bags, etc.
When the resin has set up, remove tape and temporary
screws. Clean up any resin that would interfere
with seating the antenna on the ends of the
spacers. Make sure the tinned ends of the spacers
are clean.
Fabricate at least 4 but no more than 8 'radials'
from copper foil. 3/4" to 1-1/2" wide and 21" long.
these can be multiple strips spliced together by
soldering to get desired total length. Lay these
out in as uniformly circular pattern around antenna.
Length can curve up the sides and 'hop' over
ribs, stringers, stiffeners, etc. Solder end of
radials to the brass sheet using 63/37 electronic
solder. Heavy duty iron will flow these joints
one at a time and with minutes between joints to
keep from heating the whole thing up and putting
resin at risk. Put strips of glas and resin over
the radials to keep them in place and protect from
damage.
Brighten under-surface of antenna base before
installing antenna using 10-32 grade 8 or stainless
cap head screws. Screw heads against antenna base;
MS20365 or equal metallic lock nuts over washers against
the plate. Caulk around base of antenna with RTV.
There are no doubt other ways to get an RF-SOLID
installation but this one is based on materials
and tools I have. I know too that the processes
and configuration would produce an installation
with robustness and performance difficult to
improve upon. A DC ohmmeter test of this installation
would be superfluous.
Bob . . .
________________________________________________________________________________
| From: | "Robert L. Nuckolls, III" <nuckolls.bob(at)aeroelectric.com> |
| Subject: | Re: wire squash connections |
>
>Would crimping a D-Sub female connector pin onto the end of the wire
>and adding a couple layers of shrink tube over the junction for some
>stress relief provide a better item to be pressed under the
>screw? Again assuming you would provide some wire support close to the box.
That might 'protect' the wire but now you
have a single, solid, small diameter being
captured between two surfaces having a larger
radius. I.e., potentially less contact surface
area than one could get with a compressed
stack of wire strands (19 of them when it
comes to legacy standard wire).
The guys who designed this terminal strip
were no dummies. It's really a pretty well
thought out product. But I'd bet that they
would not recommend that it be used under
the cowl on any vehicle. Not recommending
doesn't make it automatically "bad" . . .
just not the best we know how to do. I
think the risks are low.
One could use PIDG 'pins' . . .
http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=165168-ND
Bob . . .
________________________________________________________________________________
| From: | "Don" <dsvs(at)ca.rr.com> |
| Subject: | wire squash connections |
Or you could use ferrules. When they are crimper down the contact is flat.
See
http://www.alliedelec.com/search/searchresults.aspx?N=0&Ntk=Primary&Ntt=ferr
els
-----Original Message-----
From: owner-aeroelectric-list-server(at)matronics.com
[mailto:owner-aeroelectric-list-server(at)matronics.com] On Behalf Of Robert L.
Nuckolls, III
Sent: Wednesday, February 02, 2011 5:21 PM
Subject: Re: AeroElectric-List: wire squash connections
>
>Would crimping a D-Sub female connector pin onto the end of the wire
>and adding a couple layers of shrink tube over the junction for some
>stress relief provide a better item to be pressed under the
>screw? Again assuming you would provide some wire support close to the
box.
That might 'protect' the wire but now you
have a single, solid, small diameter being
captured between two surfaces having a larger
radius. I.e., potentially less contact surface
area than one could get with a compressed
stack of wire strands (19 of them when it
comes to legacy standard wire).
The guys who designed this terminal strip
were no dummies. It's really a pretty well
thought out product. But I'd bet that they
would not recommend that it be used under
the cowl on any vehicle. Not recommending
doesn't make it automatically "bad" . . .
just not the best we know how to do. I
think the risks are low.
One could use PIDG 'pins' . . .
http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=165168-ND
Bob . . .
________________________________________________________________________________
| From: | "Don" <dsvs(at)ca.rr.com> |
| Subject: | wire squash connections |
You will need to reattach the "els" to the link on the allied web site
-----Original Message-----
From: owner-aeroelectric-list-server(at)matronics.com
[mailto:owner-aeroelectric-list-server(at)matronics.com] On Behalf Of Don
Sent: Wednesday, February 02, 2011 7:50 PM
Subject: RE: AeroElectric-List: wire squash connections
Or you could use ferrules. When they are crimper down the contact is flat.
See
http://www.alliedelec.com/search/searchresults.aspx?N=0&Ntk=Primary&Ntt=ferr
els
-----Original Message-----
From: owner-aeroelectric-list-server(at)matronics.com
[mailto:owner-aeroelectric-list-server(at)matronics.com] On Behalf Of Robert L.
Nuckolls, III
Sent: Wednesday, February 02, 2011 5:21 PM
Subject: Re: AeroElectric-List: wire squash connections
>
>Would crimping a D-Sub female connector pin onto the end of the wire
>and adding a couple layers of shrink tube over the junction for some
>stress relief provide a better item to be pressed under the
>screw? Again assuming you would provide some wire support close to the
box.
That might 'protect' the wire but now you
have a single, solid, small diameter being
captured between two surfaces having a larger
radius. I.e., potentially less contact surface
area than one could get with a compressed
stack of wire strands (19 of them when it
comes to legacy standard wire).
The guys who designed this terminal strip
were no dummies. It's really a pretty well
thought out product. But I'd bet that they
would not recommend that it be used under
the cowl on any vehicle. Not recommending
doesn't make it automatically "bad" . . .
just not the best we know how to do. I
think the risks are low.
One could use PIDG 'pins' . . .
http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=165168-ND
Bob . . .
________________________________________________________________________________
| From: | Robert Borger <rlborger(at)mac.com> |
| Subject: | Re: wire squash connections |
Bob,
Yes, I can see the PIGD pin working.
If contact area is the issue, how about crimp on male spade? Lots of contact area
for the screw to mash into. It has a crimp onto the wire and a crimp onto
the insulation. Add some heat shrink tubing for strain relief and support the
wire.
Bob
On Feb 2, 2011, at 7:20 PM, Robert L. Nuckolls, III wrote:
>
>
>>
>> Would crimping a D-Sub female connector pin onto the end of the wire and adding
a couple layers of shrink tube over the junction for some stress relief provide
a better item to be pressed under the screw? Again assuming you would provide
some wire support close to the box.
>
> That might 'protect' the wire but now you
> have a single, solid, small diameter being
> captured between two surfaces having a larger
> radius. I.e., potentially less contact surface
> area than one could get with a compressed
> stack of wire strands (19 of them when it
> comes to legacy standard wire).
>
> The guys who designed this terminal strip
> were no dummies. It's really a pretty well
> thought out product. But I'd bet that they
> would not recommend that it be used under
> the cowl on any vehicle. Not recommending
> doesn't make it automatically "bad" . . .
> just not the best we know how to do. I
> think the risks are low.
>
> One could use PIDG 'pins' . . .
>
> http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=165168-ND
>
>
>
> Bob . . .
________________________________________________________________________________
| From: | "Robert L. Nuckolls, III" <nuckolls.bob(at)aeroelectric.com> |
| Subject: | Re: wire squash connections |
At 11:22 PM 2/2/2011, you wrote:
>
>Bob,
>
>Yes, I can see the PIGD pin working.
>
>If contact area is the issue, how about crimp on male spade? Lots
>of contact area for the screw to mash into. It has a crimp onto the
>wire and a crimp onto the insulation. Add some heat shrink tubing
>for strain relief and support the wire.
I like the pins better . . . or simply
the combed strands.
Bob . . .
________________________________________________________________________________
| Subject: | Re: wire squash connections |
| From: | "Bob Marshall" <marshall6916(at)sbcglobal.net> |
Great suggestions, thanks everyone!! I think I will order the ferrules from Altech
though they come in packs of 100. If I do order, does anyone want a few?
My thinking is that the ferrules will do as advertised and prevent strand breaks
and maybe a bit of oxidation, too. Just seems like a better connection.
--------
RV-6A construction resumed. Planning electrical and building wing.
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=329418#329418
________________________________________________________________________________
| Subject: | Re: wire squash connections |
Wire termination ferrules are designed for use in
connectors of the type used in P-Mags.
See digikey.com, part number 298-10044-ND for an example.
These ferrules are tin-plated copper, and they provide
an insulated segment that keeps the wire bend away from
the stripped part of the wire- this helps to prevent
flexing that can break individual wire strands.
The ferrule crimper (yes, another tool...) leaves
flat sides on the ferrule that align with the
clamp action of the terminal into which the ferrule
is inserted.
Ferrules are sized for various wire gauges, the part
number that I gave above is for #18. Ferrules are
available to receive two conductors, having a double-
width insulation sleeve. Catalogs often contain part
numbers that offer various ferrule tube lengths, but
the small connectors that are used on P-Mags would
probably lead to trimming the longer ferrules to fit,
which is OK.
I think that this approach is more desirable than the
PIDG pins, because the ferrule can be trimmed to length
so that the ferrule fits quite neatly into the receiving
area of the connector body, leaving the ferrule's insulator
supported within the box-shaped entry to the connector.
PIDG pins have enough bulk that, in some of these kinds
of connectors, the pin projects outside the confines of
the connector body: This means that the pin is essentially
a miniature cantilevered beam carrying whatever bending
load that might exist in the wire's installation. In the
long run this might result in flexing and breakage of
the PIDG pin.
Mike Linse
Corvallis, OR
>
> Bob,
>
> Yes, I can see the PIGD pin working.
>
> If contact area is the issue, how about crimp on male spade? Lots of
> contact area for the screw to mash into. It has a crimp onto the wire and
> a crimp onto the insulation. Add some heat shrink tubing for strain
> relief and support the wire.
>
> Bob
>
> On Feb 2, 2011, at 7:20 PM, Robert L. Nuckolls, III wrote:
>
>>
>>
>>
>>>
>>> Would crimping a D-Sub female connector pin onto the end of the wire
>>> and adding a couple layers of shrink tube over the junction for some
>>> stress relief provide a better item to be pressed under the screw?
>>> Again assuming you would provide some wire support close to the box.
>>
>> That might 'protect' the wire but now you
>> have a single, solid, small diameter being
>> captured between two surfaces having a larger
>> radius. I.e., potentially less contact surface
>> area than one could get with a compressed
>> stack of wire strands (19 of them when it
>> comes to legacy standard wire).
>>
>> The guys who designed this terminal strip
>> were no dummies. It's really a pretty well
>> thought out product. But I'd bet that they
>> would not recommend that it be used under
>> the cowl on any vehicle. Not recommending
>> doesn't make it automatically "bad" . . .
>> just not the best we know how to do. I
>> think the risks are low.
>>
>> One could use PIDG 'pins' . . .
>>
>> http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=165168-ND
>>
>>
>>
>> Bob . . .
>
________________________________________________________________________________
| From: | "Don" <dsvs(at)ca.rr.com> |
| Subject: | Re: wire squash connections |
Bob I use them on my P-MAGS. Like Bob N says these will not form gas tight
connections in screw down devices, but they do provide a fairly lagre
contact area and they keep the wire from being stressed. I check mine every
condition inspection. So far I have not needed to replace any wires but it
will be easy when the time comes. I wish that the P_MAGS came with D-SUB
connectors, but I am not holding my breath. Don
-----Original Message-----
From: owner-aeroelectric-list-server(at)matronics.com
[mailto:owner-aeroelectric-list-server(at)matronics.com] On Behalf Of Bob
Marshall
Sent: Wednesday, February 02, 2011 9:32 PM
Subject: AeroElectric-List: Re: wire squash connections
Great suggestions, thanks everyone!! I think I will order the ferrules from
Altech though they come in packs of 100. If I do order, does anyone want a
few?
My thinking is that the ferrules will do as advertised and prevent strand
breaks and maybe a bit of oxidation, too. Just seems like a better
connection.
--------
RV-6A construction resumed. Planning electrical and building wing.
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=329418#329418
________________________________________________________________________________
| From: | "Bill Bradburry" <bbradburry(at)bellsouth.net> |
| Subject: | Re: wire squash connections |
If it is an experimental plane, put some on if you want.
Bill B
-----Original Message-----
From: owner-aeroelectric-list-server(at)matronics.com
[mailto:owner-aeroelectric-list-server(at)matronics.com] On Behalf Of Don
Sent: Thursday, February 03, 2011 12:53 AM
Subject: RE: AeroElectric-List: Re: wire squash connections
Bob I use them on my P-MAGS. Like Bob N says these will not form gas tight
connections in screw down devices, but they do provide a fairly lagre
contact area and they keep the wire from being stressed. I check mine every
condition inspection. So far I have not needed to replace any wires but it
will be easy when the time comes. I wish that the P_MAGS came with D-SUB
connectors, but I am not holding my breath. Don
-----Original Message-----
From: owner-aeroelectric-list-server(at)matronics.com
[mailto:owner-aeroelectric-list-server(at)matronics.com] On Behalf Of Bob
Marshall
Sent: Wednesday, February 02, 2011 9:32 PM
Subject: AeroElectric-List: Re: wire squash connections
Great suggestions, thanks everyone!! I think I will order the ferrules from
Altech though they come in packs of 100. If I do order, does anyone want a
few?
My thinking is that the ferrules will do as advertised and prevent strand
breaks and maybe a bit of oxidation, too. Just seems like a better
connection.
--------
RV-6A construction resumed. Planning electrical and building wing.
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=329418#329418
________________________________________________________________________________
| From: | "Roger" <mrspudandcompany(at)verizon.net> |
| Subject: | wire squash connections |
>>If contact area is the issue, how about crimp on male spade? Lots of
>>contact area for the screw to mash into. It has a crimp onto the wire and
>>a crimp onto the insulation. Add some heat shrink tubing for strain
>>relief and support the wire.
>
> I like the pins better . . . or simply
> the combed strands.
>
>
> Bob . . .
Where I used to work we used a similar terminal in one of our
devices. We used a crimp on pin on the end of the wires before insertion.
This made for a nice looking finished job, But unless the assembly tech
really torqued the screws down very tight, they would tend to loosen.
Roger
________________________________________________________________________________
| From: | David <ainut(at)knology.net> |
| Subject: | Re: wire squash connections |
Bob, can you tell if the Labjack U12, www.labjack.com/U12 , is
suitable? I had no idea that termination was such a concern. I've had
the U12 for several years and hope to use it in my Mustang II
(Mustang2.) It was only $100 at the time I bought it as well. If I
need to get the dataq part, so be it, but it doesn't has have as many
capabilities as the Labjack.
Thanks,
David M.
Robert L. Nuckolls, III wrote:
> At 10:26 AM 2/2/2011, you wrote:
>>
>> Bob,
>>
>> Interesting. I plan to put a pair of P-Mags on the Lycoming for my
>> Toot.
>>
>> Rather than bare wires under a screw, I'd think about crimping a
>> suitably sized ring terminal onto the wire with proper shrink tube
>> and placing the ring under the screw along with a lock washer.
>>
>> Others, please chime in if there's an error in my thinking as it's
>> info I'll eventually need.
>
> Just so we're all on the same page . . .
>
> The twist-n-squash terminal strips featured in this
> thread are probably the best there is for taking
> wires to etched circuit boards with convenience,
> minimum cost and reliability . . . UNDER CERTAIN
> CONDITIONS. Here's one example of the technology:
>
> Emacs!
>
> Here's one of my favorite $100 data acquisition modules that
> uses the same terminal strip.
>
> Emacs!
>
> Note that the bared end of a wire is NOT captured by
> a head of the mash-screw . . .
>
> Emacs!
>
> But by the END of the mash-screw. Further, there is a buffer
> strip between the wire strands and the end of the screw. If one
> REALLY needs to use a twist-n-squash technology, this is one of
> the best.
>
> Legacy design goals for aviation (and other disciplines)
> have adopted processes that offer gas-tightness in the
> metallic joints of the current carrying pathway along
> with wire support immediately adjacent to the gas-tight
> joint that prevents failure of the wire under vibration.
>
> Without getting in too much of a dither about new design
> goals, I think the best application of this process calls
> for parallel strands of wire pressed into the lower
> concave surface of the cavity with force from above
> offered by the screw. Then supply bundle support within
> a couple inches of the squash-joints.
>
> Note that is NOT what I did on this particular example . . .
> but then this DAM isn't expected to be in place and
> functioning after what we hope is decades of otherwise
> unattended service.
>
> Bob . . .
>
--
If you're an American, just say NO to the Obamanation, to socialism, and get rid
of Soros.
________________________________________________________________________________
| From: | "Robert L. Nuckolls, III" <nuckolls.bob(at)aeroelectric.com> |
| Subject: | Re: wire squash connections |
At 11:45 AM 2/3/2011, you wrote:
>
>Bob, can you tell if the Labjack U12, www.labjack.com/U12 , is
>suitable? I had no idea that termination was such a concern. I've
>had the U12 for several years and hope to use it in my Mustang II
>(Mustang2.) It was only $100 at the time I bought it as well.
Suitable for what task? How do you intend to use
the device and what effects might failure of the
device have on the outcome of any given flight.
I believe the U12 is available as a bare-foot board
assembly that has no i/o terminal strip or housing.
You can solder your own i/o termination technology
to the board. But even so, you need to think through
the FMEA for having this board fail to accomplish
any given task.
If I need to get the dataq part, so be it, but it doesn't has have as
many capabilities as the Labjack.
The DataQ device has the SAME terminal strips. The
pictures showed how I reduced the inconvenience of
of those strips with a D-sub connection adaptation . . .
but the strips are still there.
Unless you're using this board to develop feedback
data for an autopilot or fuel injection system,
then I suspect that failure to perform is nothing
worse than a maintenance event. EITHER product will
offer good value.
Bob . . .
________________________________________________________________________________
| Subject: | Hydraulic crimper |
| From: | Richard Girard <aslsa.rng(at)gmail.com> |
It's Harbor Freight so the usual caveats, and at $60 it might be a bit much
just to make one set of battery cables but an EAA chapter or a group of
builders might find it affordable.
http://tinyurl.com/47aqbyd
*
*
Rick Girard
--
Zulu Delta
Mk IIIC
Thanks, Homer GBYM
It isn't necessary to have relatives in Kansas City in order to be unhappy.
- Groucho Marx
________________________________________________________________________________
| From: | David <ainut(at)knology.net> |
| Subject: | Re: wire squash connections |
My purposes for this unit are pressures (turbo (3), air(2), water, and
oil), misc switches, and possibly duct placements with the analog outs.
I also intend to use the AMD 494/495 chips with thermocouples for
temps. No system critical functions will be used with this a/d unit.
I intend to use a megasquirt family device for engine controls and rpm
reporting, etc.
Thanks,
David
Robert L. Nuckolls, III wrote:
>
>
> At 11:45 AM 2/3/2011, you wrote:
>>
>> Bob, can you tell if the Labjack U12, www.labjack.com/U12 , is
>> suitable? I had no idea that termination was such a concern. I've
>> had the U12 for several years and hope to use it in my Mustang II
>> (Mustang2.) It was only $100 at the time I bought it as well.
>
> Suitable for what task? How do you intend to use
> the device and what effects might failure of the
> device have on the outcome of any given flight.
>
> I believe the U12 is available as a bare-foot board
> assembly that has no i/o terminal strip or housing.
> You can solder your own i/o termination technology
> to the board. But even so, you need to think through
> the FMEA for having this board fail to accomplish
> any given task.
>
> If I need to get the dataq part, so be it, but it doesn't has have as
> many capabilities as the Labjack.
>
> The DataQ device has the SAME terminal strips. The
> pictures showed how I reduced the inconvenience of
> of those strips with a D-sub connection adaptation . . .
> but the strips are still there.
>
> Unless you're using this board to develop feedback
> data for an autopilot or fuel injection system,
> then I suspect that failure to perform is nothing
> worse than a maintenance event. EITHER product will
> offer good value.
>
>
> Bob . . .
>
>
--
If you're an American, just say NO to the Obamanation, to socialism, and get rid
of Soros.
________________________________________________________________________________
| From: | "Robert L. Nuckolls, III" <nuckolls.bob(at)aeroelectric.com> |
| Subject: | Re: Hydraulic crimper |
At 07:18 PM 2/3/2011, you wrote:
>It's Harbor Freight so the usual caveats, and at $60 it might be a
>bit much just to make one set of battery cables but an EAA chapter
>or a group of builders might find it affordable.
>
><http://tinyurl.com/47aqbyd>http://tinyurl.com/47aqbyd
Looks like a 'deal' to me.
Bob . . .
________________________________________________________________________________
| Subject: | Re: Hydraulic crimper |
I bought one of these and have used it on my heavy cables. Also loaned it
out to friends for automobile as well as aircraft cables. It works really
well. The crimps are easy to control and appear to be quite tight.
Michael Wynn
RV 8 Wiring
San Ramon, CA
In a message dated 2/3/2011 8:35:11 P.M. Pacific Standard Time,
nuckolls.bob(at)aeroelectric.com writes:
At 07:18 PM 2/3/2011, you wrote:
It's Harbor Freight so the usual caveats, and at $60 it might be a bit
much just to make one set of battery cables but an EAA chapter or a group of
builders might find it affordable.
_http://tinyurl.com/47aqbyd_ (http://tinyurl.com/47aqbyd)
Looks like a 'deal' to me.
Bob . . .
(http://www.matronics.com/Navigator?AeroElectric-List)
(http://www.matronics.com/contribution)
________________________________________________________________________________
| From: | Ron Quillin <rjquillin(at)cox.net> |
| Subject: | Re: Hydraulic crimper |
I too got one about six months or so ago, and have since loaned it to my IA.
Some creativity must be used in selecting the correct size die..
Oh, and get one of those 20% off coupons they send out all the time
too to make it even sweeter.
Ron Q.
At 22:14 2/3/2011, you wrote:
>I bought one of these and have used it on my heavy cables. Also
>loaned it out to friends for automobile as well as aircraft
>cables. It works really well. The crimps are easy to control and
>appear to be quite tight.
>
>Michael Wynn
>RV 8 Wiring
>San Ramon, CA
>
>In a message dated 2/3/2011 8:35:11 P.M. Pacific Standard Time,
>nuckolls.bob(at)aeroelectric.com writes:
>At 07:18 PM 2/3/2011, you wrote:
>>It's Harbor Freight so the usual caveats, and at $60 it might be a
>>bit much just to make one set of battery cables but an EAA chapter
>>or a group of builders might find it affordable.
>>
>><http://tinyurl.com/47aqbyd>http://tinyurl.com/47aqbyd
>
> Looks like a 'deal' to me.
>
> Bob . . .
>
>
>===================================
>
>List
>href="http://www.matronics.com/Navigator?AeroElectric-List">http://www.matronics.com/Navigator?AeroElectric-List
>
>===================================
>
>ms.matronics.com/">http://forums.matronics.com
>
>===================================
>
>tp://www.matronics.com/contribution">http://www.matronics.com/contribution
>
>===================================
>
>
________________________________________________________________________________
| Subject: | Icom A210 Wiring Q.. |
| From: | "chris Sinfield" <chris_sinfield(at)yahoo.com.au> |
Hi everyone.
I am wiring up my 2 seater plane and have a few Q's after reading all the info.
I will just use the internal 2 place hot mic intercom system. The wiring diagram
has an external intercom switch. Do I still need it and what is it for?
Also there are 2 options for the rear radio connection. A 30 pin molex or a 15
pin D sub.
What have people been using to connect to? Pros and cons?
I want to use the 3 audio inputs and can not see how I can do this with the D sub
and without a separate intercom box.
Also it calls for a 10 Amp CB not a fuse? is this so if you get a hot TX mic you
can pull the CB?? the Aero Electric connection guide only a 5 amp fuse for the
Icom 200/A210?? Am I missing somthing?
Chris..
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=329696#329696
________________________________________________________________________________
| From: | Mike Welch <mdnanwelch7(at)hotmail.com> |
| Subject: | Icom A210 Wiring Q.. |
> I will just use the internal 2 place hot mic intercom system. The wiring
diagram has an external intercom switch. Do I still need it and what is it
for?
>
> Also there are 2 options for the rear radio connection. A 30 pin molex or
a 15 pin D sub.
>
> What have people been using to connect to? Pros and cons?
>
> I want to use the 3 audio inputs and can not see how I can do this with t
he D sub and without a separate intercom box.
>
> Also it calls for a 10 Amp CB not a fuse? is this so if you get a hot TX
mic you can pull the CB?? the Aero Electric connection guide only a 5 amp f
use for the Icom 200/A210?? Am I missing something?
>
> Chris..
Hi Chris=2C
A few months ago=2C I asked many of the same questions to this list. I t
hink it was Bob N.
that suggested the DB15 plug. I am very pleased with the plug for a connec
tion.
I also wondered about using the internal intercom in my Icom A200. Some
guys said
they weren't especially thrilled with the internal intercom=2C and I would
be better off with
a separate panel mount one.
Although I didn't have a panel mount intercom=2C I did have a portable So
ftComm intercom=2C
and made a rectangular hole for it in my console. For the most part=2C it
looks like a built-in
model=2C and what is really nice is=2C it has all the plug receptacles and
so forth already available.
I simply took it apart and added a few wires for the things I needed to c
onvert it to panel
mount style. Wires like: positive and negative "hot"=2C so that I didn't n
eed the 9 volt battery=2C
Icom hookup wires=2C and I added the Dynon audio alarm signal to one of the
"audio in" locations.
(as per the SoftComm tech guy's approval).
After I got the whole arrangement finished=2C I'm very pleased with the r
esults! The DB15 plug
is the perfect choice=2C the separate intercom allows for more control of i
ntercom functions ( I
believe)=2C and any additional audio requirements like alarms=2C music=2C e
tc. are very easy to add.
Regarding the circuit breaker=2C the Icom installaion is not real clear.
One place says 10A=2C
then another refers to 5A. (or some kind of confusion like that). I think
I called Icom=2C but in
any event=2C I went with the 5A breaker. I think it was in the Icom's spec
s where it says it's
maximum current was around 2 amps. I have mine hooked up to a 5A breaker
=2C but I seem to
recall someone on this list said a 10A breaker would hurt. I'd just go wit
h 5.
BTW=2C there are a few intercom companies that I found that have wiring d
iagrams for
their particular intercom models to hook up to various aircraft comm radios
. Sigtronics
is one that I know of. I used their wiring diagram to coach me through the
SoftComm wiring
points. Once I felt like I had everything figured out=2C I called and veri
fied I was on the right path
with SoftComm. Worked perfect on the initial test!!!
Mike Welch
________________________________________________________________________________
| From: | "Robert L. Nuckolls, III" <nuckolls.bob(at)aeroelectric.com> |
| Subject: | Re: Icom A210 Wiring Q.. |
At 05:37 AM 2/5/2011, you wrote:
I will just use the internal 2 place hot mic intercom system. The
wiring diagram has an external intercom switch. Do I still need it
and what is it for?
The manuals are not helpful as to the function of this
switch. With a voice activated intercom, you don't need
the press-to-talk button associated with hot-mike intercoms.
However, I would suggest you bring some wires out
for this switch and then explore what it does after
you've got it up and running. It may be a handy way
to turn the intercom function OFF . . . which could
be handy if you're busy talking to controllers and you
don't want inadvertent conversation from the right seat
passenger to go out on the radio.
For all of ICOM's expertise in electronics, their
manuals leave some things to be desired. Perhaps
somebody here on the List has explored the function
of that switch and can advise you.
Also there are 2 options for the rear radio connection. A 30 pin
molex or a 15 pin D sub.
As Mike pointed out, the D-Sub is much preferred . . . .
but it does not exactly parallel the Molex connnector
for wire functions. If you need ANY of the wires in
the Molex connector for your installation, then
you're pretty much stuck with that connector. It's
not a "bad" connector but the D-sub is much "better".
I want to use the 3 audio inputs and can not see how I can do this
with the D sub and without a separate intercom box.
Aha! you've discovered the missing wires in the D-sub.
If you want to use the internal audio isolation amplifier
you'll need to use the Molex.
Also it calls for a 10 Amp CB not a fuse? is this so if you get a hot
TX mic you can pull the CB?? the Aero Electric connection guide only
a 5 amp fuse for the Icom 200/A210?? Am I missing somthing?
No, that 5A fuse call out in my drawings is an artifact
from having produced a wiring diagram for the MicroAir
760. The manuals for the ICOM call out 5A max draw in
transmit, so you need to up size to 7A fuse, or 10A or
what ever. Remember, fuses and breakers protect wires.
A long as they're matched to the wire large enough to
avoid nuisance trips, then you're good to go.
I need go fix that drawing . . . which is about 10
years old. I'm going to up size to 7A fuse. I AM a bit
disappointed that you're the FIRST to have brought it
to my attention. Thanks!
Bob . . .
________________________________________________________________________________
| Subject: | Re: Icom A210 Wiring Q.. |
| From: | Don Hudgeon <don(at)hudgeon.com> |
Hello Chris
I have recently installed a A210 in my Kitfox. I just wired in a push button
switch (like a PTT) to the intercom switch wires. One push and it either
connects or disconnects the intercom. Works great for a noisy cockpit like
mine.
Cheers
Don
On Sat, Feb 5, 2011 at 6:47 AM, Robert L. Nuckolls, III <
nuckolls.bob(at)aeroelectric.com> wrote:
> nuckolls.bob(at)aeroelectric.com>
>
>
> At 05:37 AM 2/5/2011, you wrote:
> chris_sinfield(at)yahoo.com.au>
>
>
> I will just use the internal 2 place hot mic intercom system. The wiring
> diagram has an external intercom switch. Do I still need it and what is it
> for?
>
> The manuals are not helpful as to the function of this
> switch. With a voice activated intercom, you don't need
> the press-to-talk button associated with hot-mike intercoms.
> However, I would suggest you bring some wires out
> for this switch and then explore what it does after
> you've got it up and running. It may be a handy way
> to turn the intercom function OFF . . . which could
> be handy if you're busy talking to controllers and you
> don't want inadvertent conversation from the right seat
> passenger to go out on the radio.
>
> For all of ICOM's expertise in electronics, their
> manuals leave some things to be desired. Perhaps
> somebody here on the List has explored the function
> of that switch and can advise you.
>
>
> Also there are 2 options for the rear radio connection. A 30 pin molex or a
> 15 pin D sub.
>
> As Mike pointed out, the D-Sub is much preferred . . . .
> but it does not exactly parallel the Molex connnector
> for wire functions. If you need ANY of the wires in
> the Molex connector for your installation, then
> you're pretty much stuck with that connector. It's
> not a "bad" connector but the D-sub is much "better".
>
>
> I want to use the 3 audio inputs and can not see how I can do this with the
> D sub and without a separate intercom box.
>
> Aha! you've discovered the missing wires in the D-sub.
> If you want to use the internal audio isolation amplifier
> you'll need to use the Molex.
>
> Also it calls for a 10 Amp CB not a fuse? is this so if you get a hot TX
> mic you can pull the CB?? the Aero Electric connection guide only a 5 amp
> fuse for the Icom 200/A210?? Am I missing somthing?
>
> No, that 5A fuse call out in my drawings is an artifact
> from having produced a wiring diagram for the MicroAir
> 760. The manuals for the ICOM call out 5A max draw in
> transmit, so you need to up size to 7A fuse, or 10A or
> what ever. Remember, fuses and breakers protect wires.
> A long as they're matched to the wire large enough to
> avoid nuisance trips, then you're good to go.
>
> I need go fix that drawing . . . which is about 10
> years old. I'm going to up size to 7A fuse. I AM a bit
> disappointed that you're the FIRST to have brought it
> to my attention. Thanks!
>
>
> Bob . . .
>
>
________________________________________________________________________________
| From: | "Peter Mather" <peter(at)mather.com> |
| Subject: | Heated pitot Question |
I've got a heated pitot off a C182 (28V) that I want to use on a Tailwind
I'm building (www.tailwindbuild.blogspot.com). Originally I assumed that I
would not bother with the heater as the aircraft will not be used for IFR
(not allowed for experimentals in the UK) and will have a 14V electrical
system. But, as an experiment, I wired the pitot up to my bench supply and
at 14V it pulls 4amps and gets too hot to touch. Is there any reason not to
just wire it off the 14V supply? At 50W+ of heat it presumably is better
than nothing?
Thanks
Peter
________________________________________________________________________________
| From: | "Robert L. Nuckolls, III" <nuckolls.bob(at)aeroelectric.com> |
| Subject: | Re: Heated pitot Question |
At 01:32 PM 2/5/2011, you wrote:
>I've got a heated pitot off a C182 (28V) that I want to use on a
>Tailwind I'm building
>(<http://www.tailwindbuild.blogspot.com>www.tailwindbuild.blogspot..com).
>Originally I assumed that I would not bother with the heater as the
>aircraft will not be used for IFR (not allowed for experimentals in
>the UK) and will have a 14V electrical system. But, as an
>experiment, I wired the pitot up to my bench supply and at 14V it
>pulls 4amps and gets too hot to touch. Is there any reason not to
>just wire it off the 14V supply? At 50W+ of heat it presumably is
>better than nothing?
Having a heated pitot tube was always an
option on Cessna single engine airplanes . . .
and not a cheap option either.
But if one watches some certification
programs for flight into known icing,
the idea that dumping few hundred watts of heat
into a pitot tube is a good and useful
thing to do becomes problematic.
The kind of ice that plugs a pitot tube
is also the kind of ice that covers
windshields, gathers on prop roots, leading
edges of wings. and any other sticky-out
thing like landing gear.
Any time you even THINK you've gathered
some ice, the prudent action is to take
immediate measures to get out . . . 180
turn, change altitude, etc. This (or a similar)
January 22, 2011 - February 05, 2011
AeroElectric-Archive.digest.vol-kb