Today's Message Index:
----------------------
1. 12:43 AM - Re: Odyssey PC680 Battery load tests (Jef Vervoort)
2. 03:21 AM - Re: Comm Antenna & SWR Reading -- Too High? (tomcostanza)
3. 04:50 AM - "Emacs!" in Response ()
4. 05:12 AM - Re: Flush Cutting Cable Ties (Harley)
5. 05:45 AM - Starter motors (Jan de Jong)
6. 06:50 AM - Re: "Emacs!" in Response (user9253)
7. 07:13 AM - Re: Re: "Emacs!" in Response (John Morgensen)
8. 07:26 AM - Re: Odyssey PC680 Battery load tests (Robert L. Nuckolls, III)
9. 08:11 AM - Re: Re: Comm Antenna & SWR Reading -- Too High? (Robert L. Nuckolls, III)
10. 08:16 AM - VOMs again. . . (paul wilson)
11. 09:01 AM - Re: VOMs again. . . (Mike Welch)
12. 09:23 AM - Re: VOMs again. . . (Marvin Haught)
13. 09:43 AM - Re: Comm Antenna & SWR Reading (Noel Loveys)
14. 09:58 AM - Re: cable ties (Noel Loveys)
15. 10:02 AM - Re: Comm Antenna & SWR Reading: Additional Info (Noel Loveys)
16. 10:50 AM - Re: Re: Comm Antenna & SWR Reading -- Too High? (Robert L. Nuckolls, III)
17. 11:10 AM - vor antenna (dlicheri)
18. 11:14 AM - Re: VOMs again. . . (paul wilson)
19. 11:16 AM - Re: cable ties (Stein Bruch)
20. 11:18 AM - Re: VOMs again. . . (Robert L. Nuckolls, III)
21. 11:25 AM - Re: cable ties (Robert L. Nuckolls, III)
22. 11:42 AM - Re: "Emacs!" in Response (Noel Loveys)
23. 11:42 AM - Re: VOMs again. . . (Mike Welch)
24. 11:42 AM - Re: Comm Antenna & SWR Reading (Robert L. Nuckolls, III)
25. 11:46 AM - Re: Re: "Emacs!" in Response (Dan Morrow)
26. 11:54 AM - Re: vor antenna (Robert L. Nuckolls, III)
27. 11:56 AM - Re: "Emacs!" in Response (Robert L. Nuckolls, III)
28. 11:58 AM - Re: Comm Antenna & SWR Reading (Robert L. Nuckolls, III)
29. 12:27 PM - Re: cable ties (Harley)
30. 12:42 PM - Re: cable ties (Noel Loveys)
31. 12:44 PM - Re: Comm Antenna & SWR Reading (Noel Loveys)
32. 12:48 PM - Re: "Emacs!" in Response (Noel Loveys)
33. 12:58 PM - Re: vor antenna (Noel Loveys)
34. 01:05 PM - Re: Comm Antenna & SWR Reading (Robert L. Nuckolls, III)
35. 01:12 PM - Re: vor antenna (Robert L. Nuckolls, III)
36. 01:42 PM - Re: cable ties (Robert Borger)
37. 01:50 PM - Re: vor antenna (Jared Yates)
38. 02:50 PM - Re: VOMs again. . . (Robert L. Nuckolls, III)
39. 03:17 PM - Re: VOMs again. . . (paul wilson)
40. 05:22 PM - Low resistance measurement adapter. (Robert L. Nuckolls, III)
41. 05:39 PM - Re: Low resistance measurement adapter. (Robert Borger)
42. 07:55 PM - Re: Comm Antenna & SWR Reading (Noel Loveys)
43. 08:14 PM - Re: vor antenna (Noel Loveys)
Message 1
| INDEX | Back to Main INDEX |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| 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@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] Namens Mickey
Coggins
Verzonden: woensdag 19 januari 2011 19:40
Aan: aeroelectric-list@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
<nuckolls.bob@aeroelectric.com> wrote:
<nuckolls.bob@aeroelectric.com>
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
Message 2
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: Comm Antenna & SWR Reading -- Too High? |
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
Message 3
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| 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.
=====================================================================
Time: 10:38:42 AM PST US
From: Bob Falstad <bobair@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
Message 4
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| 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
> *
> *
Message 5
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
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
Message 6
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: "Emacs!" in Response |
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
Message 7
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| 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"<fran4sew@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
>
>
Message 8
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| 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 . . .
Message 9
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: Comm Antenna & SWR Reading -- Too High? |
At 06:18 AM 1/25/2011, you wrote:
><Tom@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.
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 . . .
Message 10
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
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
Message 11
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
>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
Message 12
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| 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
> *
>
>
> *
Message 13
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| 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@matronics.com
[mailto:owner-aeroelectric-list-server@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:
<noelloveys@yahoo.ca>
>
>Bob what did you use to measure the forward and reverse power? A bird or
>just a regular SWR meter?
>
>Noel
Message 14
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
Although I have seen those tools I have never seen one used in
aviation...
Too bad... they work.
Noel
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Janet
Amtmann
Sent: January 24, 2011 5:20 PM
Subject: AeroElectric-List: cable ties
To those of you having trouble with cable tie injuries, try a relatively
inexpensive ($31) tensioning tool from Waytek. It has a cutter that
cuts so
close to the tie head that you can't feel the edges. Try tool #412, and
use
Thomas & Betts "Ty-Rap" brand ties. Never had a problem with injuries
with
this combination. The jewelers' diags that Bob mentioned work also on a
lower budget.
Do not archive
J=FCrgen Amtmann
Message 15
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| 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@matronics.com
[mailto:owner-aeroelectric-list-server@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
Message 16
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: Comm Antenna & SWR Reading -- Too High? |
At 10:07 AM 1/25/2011, you wrote:
><nuckolls.bob@aeroelectric.com>
>
>At 06:18 AM 1/25/2011, you wrote:
>><Tom@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.
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 . . .
Message 17
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
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
Message 18
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
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
>
Message 19
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
The reason we don=92t use them extensively in aviation is they are
sometimes
really difficult to actually use in the places/locations you=92d want to
use
them (up under panels, etc..). The =93automatic tools=94 frankly can be
clunky
to use in confined areas. We own several, but usually choose to use a
little $8 flush cutter / diagonal flush cutter (the more expensive ones
are
slightly higher in quality). Much easier, faster, cheaper=85and much
smaller.
My vote is for the flush cutters=85and I feel your pain! Lots of
scratched
hands/arms over the years of doing this!
Cheers,
Stein
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Noel
Loveys
Sent: Tuesday, January 25, 2011 11:55 AM
Subject: RE: AeroElectric-List: cable ties
Although I have seen those tools I have never seen one used in
aviation...
Too bad... they work.
Noel
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Janet
Amtmann
Sent: January 24, 2011 5:20 PM
Subject: AeroElectric-List: cable ties
To those of you having trouble with cable tie injuries, try a relatively
inexpensive ($31) tensioning tool from Waytek. It has a cutter that
cuts so
close to the tie head that you can't feel the edges. Try tool #412, and
use
Thomas & Betts "Ty-Rap" brand ties. Never had a problem with injuries
with
this combination. The jewelers' diags that Bob mentioned work also on a
lower budget.
Do not archive
J=FCrgen Amtmann
http://www.matronics.com/Navigator?AeroElectric-List
http://forums.matronics.com
http://www.matronics.com/contribution
Message 20
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| 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 . . .
Message 21
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
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 . . .
Message 22
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| 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@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of
bakerocb@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.
=====================================================================
Time: 10:38:42 AM PST US
From: Bob Falstad <bobair@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
Message 23
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
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@matronics.com
> From: pwmac@sisna.com
> Subject: RE: AeroElectric-List: VOMs again. . .
>
>
> Mike what was it R scale? Max value?
> PW
Message 24
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| 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 . . .
Message 25
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: "Emacs!" in Response |
On 01/25/2011 07:11 AM, John Morgensen wrote:
> <john@morgensen.com>
>
> 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.
Message 26
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
At 02:07 PM 1/25/2011, you wrote:
><triangulumx@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.
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 . . .
Message 27
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| 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 . . .
Message 28
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| 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 . . .
Message 29
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
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" <nuckolls.bob@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 . . .
>
Message 30
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
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@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Robert L.
Nuckolls, III
Sent: January 25, 2011 2:52 PM
Subject: RE: AeroElectric-List: cable ties
<nuckolls.bob@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 . . .
Message 31
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| 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@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Robert L.
Nuckolls, III
Sent: January 25, 2011 3:09 PM
Subject: RE: AeroElectric-List: Comm Antenna & SWR Reading
<nuckolls.bob@aeroelectric.com>
At 12:38 PM 1/25/2011, you wrote:
<noelloveys@yahoo.ca>
>
>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 . . .
Message 32
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| 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@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Robert L.
Nuckolls, III
Sent: January 25, 2011 3:23 PM
Subject: RE: AeroElectric-List: "Emacs!" in Response
<nuckolls.bob@aeroelectric.com>
>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 . . .
Message 33
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
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@matronics.com
[mailto:owner-aeroelectric-list-server@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:
<triangulumx@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.
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 . . .
Message 34
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| 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 . . .
Message 35
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
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 . . .
Message 36
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
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
Message 37
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
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@aeroelectric.com> wrote:
> nuckolls.bob@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 . . .
>
>
Message 38
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| 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 . . .
Message 39
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| 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 . . .
Message 40
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| 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 . . .
Message 41
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: Low resistance measurement adapter. |
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 . . .
Message 42
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| 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@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Robert L.
Nuckolls, III
Sent: January 25, 2011 4:31 PM
Subject: RE: AeroElectric-List: Comm Antenna & SWR Reading
<nuckolls.bob@aeroelectric.com>
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 . . .
Message 43
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
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@matronics.com
[mailto:owner-aeroelectric-list-server@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@aeroelectric.com> wrote:
<nuckolls.bob@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.
====
Other Matronics Email List Services
These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.
-- Please support this service by making your Contribution today! --
|