Today's Message Index:
----------------------
1. 12:36 AM - Re: earth shield earthing (JOHN TIPTON)
2. 06:53 AM - Re: Re: antenna connections (Robert L. Nuckolls, III)
3. 07:13 AM - Re: antenna connections (messydeer)
4. 07:32 AM - Re: Ship voltmeter system limits (jonlaury)
5. 08:13 AM - Re: Jabiru 3300 Over Voltage (Noel Loveys)
6. 08:24 AM - Re: Re: antenna connections (Lynn Cole)
7. 08:27 AM - Re: Re: antenna connections (Robert L. Nuckolls, III)
8. 09:00 AM - Antennae continuity (Dennis Ramsey)
9. 09:09 AM - Re: antenna connections (messydeer)
10. 09:46 AM - Garmin 400 series simulator (DCS317@aol.com)
11. 10:55 AM - Re: Garmin 400 series simulator (BobsV35B@aol.com)
12. 11:07 AM - Re: Garmin 400 series simulator (Brantel)
13. 11:34 AM - Re: Re: Garmin 400 series simulator (BobsV35B@aol.com)
14. 12:31 PM - Re: Re: antenna connections (Lynn Cole)
15. 01:06 PM - Re: Garmin 400 series simulator (Brantel)
16. 04:15 PM - Re: Antennae continuity (Robert L. Nuckolls, III)
17. 04:19 PM - Re: Re: antenna connections (Robert L. Nuckolls, III)
18. 04:19 PM - Re: Re: antenna connections (Noel Loveys)
19. 04:29 PM - Re: Re: antenna connections (Robert L. Nuckolls, III)
20. 04:47 PM - Re: Re: Garmin 400 series simulator (BobsV35B@aol.com)
21. 05:28 PM - Re: Main panel power supply fuse (Robert L. Nuckolls, III)
22. 11:43 PM - Re: Antennae continuity (Dennis Ramsey)
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: | Re: earth shield earthing |
Hi Bob
Yes: that's the one:
http://www.aeroelectric.com/articles/shldwire/shldwire.html
Many thanks
John
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=358347#358347
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: antenna connections |
At 08:27 PM 11/17/2011, you wrote:
Thanks for the silver solder info, Bob.
What would be wrong with using a 3/16 or 1/4" rod of aluminum instead
of SS and cut threads on the end? It's much easier to bend and a 2'
piece of it from ACS is cheaper than a cup of coffee. It wouldn't fit
into the 3/8-24 mount, but an adapter from a short piece of 3/4" rod
aluminum could be made. Drill and tap one end for 3/8-24 and the
other to fit the rod. You could even taper the adapter into a cone shape.
Excellent question!
Unlike steel, aluminum has a 'service life' at
any stress level. Non-ferrous (no iron) materials
have a stress-to-cycles curve that goes all the
way down to zero stress. This means that the thing
is going to break sometime at what ever stress
level you choose to operate it.
Wings and things on aluminum airplanes are very
lightly stressed so that their service lives are
many times greater than the expected lifetime of
the machine. Yet, pieces of aluminum routinely
crack and fail. Sometimes it blows big holes out
of the cabin walls of airliners!
Steels are pretty cool in this regard. Once you
drop below a certain stress level for that particular
alloy, the service life becomes unlimited. I used
to wonder at the legacy policy of allowing an engine
to be 'certified' with only 75 or so hours on the
test stand. But 75 hours at 2400 rpm is over ten
million stress cycles on parts. If something doesn't
break in that period of time, probability of breaking
beyond this test interval is low.
Getting back to our antenna, you'll find that the
little whisker of metal 'hums' in the breeze of aero-
dynamic turbulence around the fuselage. Unless it's
a very robust aluminum part, you'll probably find that
the comm system performance becomes severely degraded
when the antenna departs the airplane.
For that reason, "whisker" style antennas have always
been made from steels . . . although from a radio
frequency performance perspective, we'd like to have
better conducting materials. This is why the 'shark fin'
antennas can offer incrementally better performance.
Their less robust, high performance materials are
enclosed in an RF transparent housing to protect them
from effects of air flow.
Bob . . .
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: | Re: antenna connections |
Yeah, that sounds familiar about aluminum. On the other hand, I've found some antennas
made out of aluminum.
The DM C63-Series antennas are VHF communication antennas designed for high mechanical
strength with machine tapered aluminum alloy radiating elements.
http://www.aircraftspruce.com/catalog/avpages/c63_2.php
Is there anything different about this type of antenna compared to the one I'd
suggested, outside of a streamlined base?
--------
Dan
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=358368#358368
Attachments:
http://forums.matronics.com//files/aluminum_antenna_929.jpg
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: Ship voltmeter system limits |
Picture's worth a 1000 words. Thanks, Bob.
And for getting me off the notion that there's any utility in a 12v battery showing
less than 10.5v.
John
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=358370#358370
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 |
|
Subject: | Jabiru 3300 Over Voltage |
Most of the problems I've seen have all had to do with faulty grounding.
For some reason it is the ground wires that seem to get the most corrosion.
The voltage regulator of your engine references the voltage on the buss
against ground. If the ground is weak or open (completely corroded) the
regulator will just allow whatever voltage is produced to be fed to the
buss.
Several regulators/ rectifier regulators ground through the case to the fire
wall. Mounting on a rubber damper or using a silicon sealer will not give
you the reference ground you need. My advice is to remove the regulator
clean both the back of the regulator and the space it will be mounted to
until both are shiny and remount the regulator then test for operation
If it works properly good... If not check the grounds between the engine
block and the frame of the plane. There should be a good heavy braid
connecting the engine block to the frame. That braid jumps out the engine
mounts and allows proper voltage to be read from the frame of the plane.
Make sure all the ring connectors are clean and shiny and the bolt/nots are
also clean and the areas the connectors land on are shiny. I like to give
all those connections a coat of the thinnest heavy grease possible after
they are torque down to help prevent future corrosion.
There is a small chance your regulator has an internal fault. Any
automotive electric shop can check it for you.
Noel
-----Original Message-----
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of David
Sent: November 16, 2011 2:42 AM
Subject: Re: AeroElectric-List: Jabiru 3300 Over Voltage
First, suspect the voltmeter. Get a (calibrated) second meter and check
it out. Easy to do that.
Ammeters are cheap. Please install one, at least temporarily until this
problem is solved.
It does sound as if the voltage regulator is not cooperating fully.
simple, but that is all I know is simple stuff.
David M.
zqqmin wrote:
> --> AeroElectric-List message posted by: "zqqmin"<zqqmin@hotmail.com>
>
> Need some help. First please understand that electricity is NOT my bag!
I have read Bob Knuckolls book, I just wish I understood it!
>
> I have a Sonex with a Jabiru 3300 engine. I see voltages ranging from
12.3 at idle to over 16 volts at climb power! I talked with Jabiru and they
suggested I change the yellow wire from the voltage regulator (control
voltage) to the main bus from the + side of the capacitor (see attached
schematic) to read "cleaner" voltage. I did this and I now get voltages of
16 volts at cruise power! I have installed Bob Knuckolls "crowbar over
voltage" circuit from B&C. I have never tripped the over voltage circuit
(5A C/B) BUT, I have blown the 10A fuse (twice) in the master switch
circuit. I reads the voltage in 3 places, the MGL Enigma EFIS, the MGL V10
Comm radio and the MicroAir Transponder....they all read the same. I do NOT
have an ammeter. BTW, I can control the voltage by turning on the landing
lights. Then I get about 12.6v at climb power.
>
> I read the Jabiru manual and it tells me the voltage regulator should
output 14 + or - .8 volts at cruise power. Is my schematic correct or do I
have an error??? I think I have a bad voltage regulator. I have 18.3 hours
of time in the phase 1 testing.
>
> Thanks in advance.
>
> --------
> Dale A. Gray
> Sonex N506DG
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=358062#358062
>
>
> Attachments:
>
> http://forums.matronics.com//files/dales_schematic_204.jpg
>
>
>
--
If you're an American, just say NO to the Obamanation, to socialism, and get
rid of Soros.
...democracy and a republic can function only in a firm partnership with
morality and religion. -- John Adams. Indeed. Same should be said for ANY
type of gubmnt
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: antenna connections |
> Getting back to our antenna, you'll find that the
> little whisker of metal 'hums' in the breeze of aero-
> dynamic turbulence around the fuselage. Unless it's
> a very robust aluminum part, you'll probably find that
> the comm system performance becomes severely degraded
> when the antenna departs the airplane.
The humming that you refer to is due to vortex shedding (the most
famous example of vortex shedding is the failure of the Tacoma
Narrows Bridge). The antenna on my car (steel) has a spiral wrap
around it. That trips the boundary layer so that only very short
stiff lengths of the antenna can vibrate. The vibrations where the
wrap is on one side of the antenna cancel the vibrations where the
wrap is on the other side. Without the wrap the entire antenna,
which is very limber, vibrates as a unit, and it can achieve some
large amplitudes.
Lynn Cole
LynnCole@foxvalley.net
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: antenna connections |
>
>Is there anything different about this type of antenna compared to
>the one I'd suggested, outside of a streamlined base?
Probably. I didn't intend to suggest that antennas
made from aluminum are not practical. When you have
the engineering and purchasing options to optimize a
design to its intended purpose, then the product can
be pretty finely tuned with respect to trade-offs.
Metals are finicky things. A perfectly robust piece
of metal can become very fragile when scratched. Cutting
threads on a rod might be called "very deep scratches."
Disruptions of an otherwise smooth surface become local
stress risers that predict where a crack will start.
I'm not a processes and materials guy so my working
knowledge is limited to what 'rubbed off' while working
around folks who really good at it.
Given that I have no control over materials, processes and
target airframes, my recommendations have to be as
goof-proof as I can imagine. As long as your airplane isn't
a pusher, then there's no risk to the airframe for shedding
an antenna. If you're interested in crafting a recipe for
success and find the risks acceptable, then give it a try.
Bob . . .
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: | Antennae continuity |
Probably a dumb question but I will ask it anyway. I always check for
continuity and shorts any time I build a coax connection. But I got the
bright idea today that I should also check the continuity from the panel
end of the cable to the com antennae itself. Got good continuity between
shield and the antennae screws and no continuity between the center
conductor and the antennae rod itself. I am guessing that this is due to
their being an insulator between the internal antennae wire and the
external metal rod of the antennae. Is that correct? I know the cable was
good (or at least tested good) before I connected it to the com antennae.
I had always assumed that the com antennae rod was a conductive part of the
transmit center conductor.
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: antenna connections |
Interesting. How wide and thick is this spiral wrap? What is the gap between one
wrap and the next? And why don't we see this feature in airplane antennas? Where
weight is the devil, seems saving an ounce would make it attractive to antenna
makers.
--------
Dan
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=358381#358381
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 |
|
Subject: | Garmin 400 series simulator |
Before shooting approaches in my RV-8 with my Garmin 430W , I like to
practice them on the computer with the Garmin 400 series simulator (lots cheaper
than $6.00 avgas). Problem is that Garmin has not updated the simulator
program since 2008, and many of the GPS approaches have changed or did not
exist in 2008. A call to Garmin tech support was not helpful, although
pleasant. They support the Garmin 400 series for repair, but have no
interest in updating the simulator, especially since they will stop manufacturing
the 400/500 series this month or soon thereafter. Garmin is not willing to
give simulator users any clues as to how to update the simulator
approaches, even if you (as I do) pay the big bucks for the monthly airdata and
obstacle updates (plus Chelton updates). (Yeah, the Cheltons are "primary", so
much easier to use and much more intuitive, but that is a whole nother
story, the 430W making things legal.)
Any computer gurus out there who can give a method of updating the
simulator files with the Jeppesen airdata and Garmin obstacle data? It would
seem
that with ever a 100,000 units installed, someone else would also have an
interest in this simulator upgrade and the advantages of the safety aspects
(and cost savings) in using the updated simulator to practice approaches.
And why not Garmin?
I've checked the blogs--can't find anything to hack the program or install
the recent airdata. Help!
Don
RV-8 Aviator
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 |
|
Subject: | Re: Garmin 400 series simulator |
Good Afternoon Don,
I have always done as do you. Find it very helpful when actually shooting
the approach.
My take is that Garmin is not at all a NICE company. The folks they have
manning the telephone lines are great. Customer service is very good, but
management stinks.
I have tried to talk to them whenever the opportunity has arisen, but all
I get is "don't bother me kid", we know what we are doing and we do not
want to hear from users.
I will say that the company that I thought was the very best at listening
to customers was Trimble and they are no longer in the business! <NG>
Maybe Garmin is right, but I do not think so.
Avidyne is now making a major effort to get into that market. I have found
the Avidyne folks to be very easy to talk to. One of my friends, a retired
airline type, had a couple of issues with the programing of Avidyne's new
IFD 540. He talked to them at the ABS convention in Las Vegas last month and
within a week was advised that they will do as he asked. I had planned on
including a new 530W in my next panel. May have even considered a Garmin
750. but after talking to the Avidyne folks at Oshkosh, I placed an order for
the new Avidyne IFD 540. It was not the box itself that sold me. it was
the attitude of the folks presenting the product.
While I have not yet bought any Aspen products, I am sure I will as their
representatives seem much more like the Avidyne folks than like the Garmin
group.
The name of the game is competition. Garmin has 'owned' the market far too
long.
Happy Skies,
Old Bob
AKA
Bob Siegfried
Downers Grove, IL
In a message dated 11/18/2011 11:47:09 A.M. Central Standard Time,
DCS317@aol.com writes:
Before shooting approaches in my RV-8 with my Garmin 430W , I like to
practice them on the computer with the Garmin 400 series simulator (lots
cheaper than $6.00 avgas). Problem is that Garmin has not updated the simulator
program since 2008, and many of the GPS approaches have changed or did not
exist in 2008. A call to Garmin tech support was not helpful, although
pleasant. They support the Garmin 400 series for repair, but have no
interest in updating the simulator, especially since they will stop manufacturing
the 400/500 series this month or soon thereafter. Garmin is not willing to
give simulator users any clues as to how to update the simulator
approaches, even if you (as I do) pay the big bucks for the monthly airdata and
obstacle updates (plus Chelton updates). (Yeah, the Cheltons are "primary", so
much easier to use and much more intuitive, but that is a whole nother
story, the 430W making things legal.)
Any computer gurus out there who can give a method of updating the
simulator files with the Jeppesen airdata and Garmin obstacle data? It would
seem
that with ever a 100,000 units installed, someone else would also have an
interest in this simulator upgrade and the advantages of the safety aspects
(and cost savings) in using the updated simulator to practice approaches.
And why not Garmin?
I've checked the blogs--can't find anything to hack the program or install
the recent airdata. Help!
Don
RV-8 Aviator
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: Garmin 400 series simulator |
You are in luck....I figured out how to upgrade it by using the database that is
in the new 650/750 simulator.
Check out this thread:
http://www.vansairforce.com/community/showthread.php?t=76306&highlight=Simulator+database
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=358392#358392
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: | Re: Garmin 400 series simulator |
Good Afternoon Brantel,
Fantastic! Is it something we mortals can handle or will it only be doable
by you special folks?
Happy Skies,
Old Bob
In a message dated 11/18/2011 1:08:49 P.M. Central Standard Time,
bchesteen@hughes.net writes:
http://www.vansairforce.com/community/showthread.php?t=76306&highlight=Simul
ator+database
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 |
|
Subject: | Re: antenna connections |
The antenna, itself tapers from about 0.175" at the base to about
0.100" at the tip. The wrap is quite thin - about 0.005-0.008"
diameter, and the pitch of the spiral is about 1 inch. The wrap is
solidly bonded to the antenna for its entire length. I suspect that
it adds some drag to the antenna, but in the car the added drag would
be very minor compared to the overall drag of the vehicle. It's a
good question as to why we don't see such a wrap on aircraft antennae.
Lynn Cole
LynnCole@foxvalley.net
On Nov 18, 2011, at 11:02 AM, messydeer wrote:
> <messydeer@yahoo.com>
>
> Interesting. How wide and thick is this spiral wrap? What is the
> gap between one wrap and the next? And why don't we see this
> feature in airplane antennas? Where weight is the devil, seems
> saving an ounce would make it attractive to antenna makers.
>
> --------
> Dan
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=358381#358381
>
>
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: | Re: Garmin 400 series simulator |
It is easy cuz I already converted the databases. The directions are in the thread
linked to above. You can view that thread without joining the VAF forums.
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=358401#358401
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: Antennae continuity |
At 10:56 AM 11/18/2011, you wrote:
Probably a dumb question but I will ask it anyway. I always check
for continuity and shorts any time I build a coax connection. But I
got the bright idea today that I should also check the continuity
from the panel end of the cable to the com antennae itself. Got good
continuity between shield and the antennae screws and no continuity
between the center conductor and the antennae rod itself. I am
guessing that this is due to their being an insulator between the
internal antennae wire and the external metal rod of the
antennae. Is that correct? I know the cable was good (or at least
tested good) before I connected it to the com antennae. I had always
assumed that the com antennae rod was a conductive part of the
transmit center conductor.
I presume we're talking about a manufactured
antenna . . . what brand and p/n? What you've
described not common in my experience . . . but not
impossible to imagine.
Every DIY antenna makes a direct connection between
the coax center conductor and the bottom of the
antenna mast. The 'pure' 1/4-wave antenna supported
over the 'ideal' ground plane has a base impedance
on the order of 20 ohms. This tells us that direct
connection of a 50 ohm coax feed line will produce
a best SWR of at least 2:1 that rises either side
of resonance for the antenna.
Many VHF/UHF antennas seen on the ground feature drooping
radials. Bending the radials downward has a doubly
beneficial effect. The feed point impedance rises.
At about 45 degrees of droop, the impedance approaches
50 ohms thus providing a better SWR. It also has the
effect of lowering the radiation angle for the antenna
thus improving performance for talking/listening to
stations just above the horizon.
VHF antennas for airplanes are exceedingly limited with
respect to optimization for lowest SWR. Fortunately,
VHF communications are light of sight. A few watts and
a wet string for an antenna will let you talk as far
as you commonly need to talk . . . a distance that
seldom extends out the horizon. So the mediocre 1/4-wave
whisker feed directly with a 50 ohm coax offers
no observable degradation of performance.
Occasionally, a design goal for a new antenna
design calls for lower SWR. It may not let you
talk or listen further, but it does look 'better'
in the sales literature. A variety of matching
techniques can be used to bring the load
impedance of the finished antenna closer to
that of the feed line. If that network includes
capacitors . . . it would explain the loss of DC
continuity from coax center conductor to antenna
mast. For any such matching circuit to exist,
there must be a sufficient volume within a base
fairing to house the components.
I've not seen antennas with matching networks
crafted with capacitors . . . but it's possible.
It's also possible that continuity measured from
center conductor to ground in an inductively compensated
antenna might approach zero ohms leading the observer
to think that it's 'shorted'.
Continuity tests for open feed lines are always
informative. But in cases of confusing ohmmeter
measurements to the antenna itself, checking the
SWR of an installed antenna is the true test
for proper function.
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 |
|
Subject: | Re: antenna connections |
At 11:02 AM 11/18/2011, you wrote:
>
>Interesting. How wide and thick is this spiral wrap? What is the gap
>between one wrap and the next? And why don't we see this feature in
>airplane antennas? Where weight is the devil, seems saving an ounce
>would make it attractive to antenna makers.
Adding the wrap is another process that adds to
cost of the finished product. If you can make the
critter survive without it, then perhaps you're
a few shekels ahead in the game. Then too, that
fix applies only to the phenomenon identified
as vortex shedding. There's turbulence in the
air behind a propeller that supplies yet another
vibration input.
Bob . . .
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 |
|
Subject: | Re: antenna connections |
Several aviation antennae are actually embedded in fibreglass forms so you
actually don't see any of the actual antenna. On some composite planes the
antennae are built in to either the wings or the tail leaving nothing
exposed at all. Having worked with Scaled Composites, Bob must have a
wealth of experience in that field..
Noel
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Lynn Cole
Sent: November 18, 2011 4:57 PM
Subject: Re: AeroElectric-List: Re: antenna connections
The antenna, itself tapers from about 0.175" at the base to about 0.100" at
the tip. The wrap is quite thin - about 0.005-0.008" diameter, and the
pitch of the spiral is about 1 inch. The wrap is solidly bonded to the
antenna for its entire length. I suspect that it adds some drag to the
antenna, but in the car the added drag would be very minor compared to the
overall drag of the vehicle. It's a good question as to why we don't see
such a wrap on aircraft antennae.
Lynn Cole
LynnCole@foxvalley.net
On Nov 18, 2011, at 11:02 AM, messydeer wrote:
Interesting. How wide and thick is this spiral wrap? What is the gap between
one wrap and the next? And why don't we see this feature in airplane
antennas? Where weight is the devil, seems saving an ounce would make it
attractive to antenna makers.
--------
Dan
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=358381#358381
(And Get Some AWESOME FREE Gifts!)
November is the Annual List Fund Raiser. Click on
the Contribution link below to find out more about
this year's Terrific Free Incentive Gifts provided
by:
* AeroElectric www.aeroelectric.com
www.buildersbooks.com
www.homebuilthelp.com
List Contribution Web Site:
--> http://www.matronics.com/contribution
Thank you for your generous support!
-Matt Dralle, List Admin.
- The AeroElectric-List Email Forum -
--> http://www.matronics.com/Navigator?AeroElectric-List
- MATRONICS WEB FORUMS -
http://forums.matronics.com
- List Contribution Web Site -
-Matt Dralle, List Admin.
--> http://www.matronics.com/contribution
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 |
|
Subject: | Re: antenna connections |
At 02:26 PM 11/18/2011, you wrote:
>The antenna, itself tapers from about 0.175" at the base to about
>0.100" at the tip. The wrap is quite thin - about 0.005-0.008"
>diameter, and the pitch of the spiral is about 1 inch. The wrap is
>solidly bonded to the antenna for its entire length. I suspect that
>it adds some drag to the antenna, but in the car the added drag
>would be very minor compared to the overall drag of the
>vehicle. It's a good question as to why we don't see such a wrap on
>aircraft antennae.
It's possible that the wrap we see on car antennas
has two purposes. The first being aerodynamic as
previously explored. The second may be that the wrap
is also a metallic conductor that serves as
the antenna supported on a Fiberglas rod.
Bob . . .
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: Garmin 400 series simulator |
Good Evening Brantel,
Fantastic!.. Not sure how it happened as I still know nothing about moving
data from one page to another, but I blindly followed your instructions and
my Garmin 400W/500W simulator now has the database that expired June 30,
2011.
That was so easy that it re-enforces my opinion that Garmin just does not
care about we who have their older boxes. If I was able to move that data,
it is obvious that any of their techies could have done it on their website
with just a second or two of effort. Thank you for guiding me through the
process, but it makes me even more angry with Garmin's attitude.
Happy Skies,
Old Bob
In a message dated 11/18/2011 1:08:49 P.M. Central Standard Time,
bchesteen@hughes.net writes:
--> AeroElectric-List message posted by: "Brantel" <bchesteen@hughes.net>
You are in luck....I figured out how to upgrade it by using the database
that is in the new 650/750 simulator.
Check out this thread:
http://www.vansairforce.com/community/showthread.php?t=76306&highlight=Simul
ator+database
In a message dated 11/18/2011 1:08:49 P.M. Central Standard Time,
bchesteen@hughes.net writes:
--> AeroElectric-List message posted by: "Brantel" <bchesteen@hughes.net>
You are in luck....I figured out how to upgrade it by using the database
that is in the new 650/750 simulator.
Check out this thread:
http://www.vansairforce.com/community/showthread.php?t=76306&highlight=Simul
ator+database
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=358392#358392
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 |
|
Subject: | Re: Main panel power supply fuse |
At 10:26 PM 11/17/2011, you wrote:
Hi folks. Appreciate advice on following.
I am finishing up wiring a CH750 with a Rotax 912ULS and a composite
design power panel. None of the "typical" wiring diagrams I have
show a fuse on the main power supply from the battery (master
solenoid) to the panel. I am using a 10 gauge tefzel feed cable
which is about 5' long.
Is it not good practice to install a "mega fuse" as close to the
master solenoid as possible to prevent fires and to protect this
circuit in the event of a short? Ive calculated that a 60 amp
fuse will be more than sufficient for all foreseeable loads.
You won't find circuit protection for that
feeder in a Part 23/25 certificated airplane. The
rationale is illustrated by the following excerpt
from Part 23:
Sec. 23.1357 Circuit protective devices.
(a) Protective devices, such as fuses or circuit breakers, must be
installed in all electrical circuits other than--
(1) Main circuits of starter motors used during starting only; and
(2) Circuits in which no hazard is presented by their omission.
(b) A protective device for a circuit essential to flight safety may not be
used to protect any other circuit.
(c) Each resettable circuit protective device ("trip free" device in which
the tripping mechanism cannot be overridden by the operating
control) must be
designed so that--
(1) A manual operation is required to restore service after tripping; and
(2) If an overload or circuit fault exists, the device will open the
circuit regardless of the position of the operating control.
(d) If the ability to reset a circuit breaker or replace a fuse is
essential to safety in flight, that circuit breaker or fuse must be so
located and identified that it can be readily reset or replaced in flight.
(e) For fuses identified as replaceable in flight--
(1) There must be one spare of each rating or 50 percent spare fuses of
each rating, whichever is greater; and
(2) The spare fuse(s) must be readily accessible to any required pilot.
The operative words that speak to your question are in Paragraph
(a)(2). Under what conditions would you expect this wire
to become overloaded to a degree that puts that wire at risk?
To open 60A protection in that feeder you would have to drag the
feeder itself or the bus to ground with a really hard fault. Hard
faults on a skillfully installed wire or bus structure required
a lot of damage to be done . . . like a crash. One assumes that
preparation for hard landing includes killing the master switch.
If the airplane is at risk for suffering that much damage with
no time for pre-landing preparation, post crash fire from hot
wiring is probably the least of your worries.
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: | Re: Antennae continuity |
Bob, the antennae is a RA Miller AV-17. More information...when I
removed the coax and held my multimeter probe to the center connection and
checked continuity to the antennae rod, I still get no continuity. So
either the antennae is bad or there is something inherent in the design
that electrically isolates the external skin of the rod.
On Fri, Nov 18, 2011 at 7:10 PM, Robert L. Nuckolls, III <
nuckolls.bob@aeroelectric.com> wrote:
> nuckolls.bob@aeroelectric.com**>
>
>
> At 10:56 AM 11/18/2011, you wrote:
>
> Probably a dumb question but I will ask it anyway. I always check for
> continuity and shorts any time I build a coax connection. But I got the
> bright idea today that I should also check the continuity from the panel
> end of the cable to the com antennae itself. Got good continuity between
> shield and the antennae screws and no continuity between the center
> conductor and the antennae rod itself. I am guessing that this is due to
> their being an insulator between the internal antennae wire and the
> external metal rod of the antennae. Is that correct? I know the cable was
> good (or at least tested good) before I connected it to the com antennae.
> I had always assumed that the com antennae rod was a conductive part of
> the transmit center conductor.
>
> I presume we're talking about a manufactured
> antenna . . . what brand and p/n? What you've
> described not common in my experience . . . but not
> impossible to imagine.
>
> Every DIY antenna makes a direct connection between
> the coax center conductor and the bottom of the
> antenna mast. The 'pure' 1/4-wave antenna supported
> over the 'ideal' ground plane has a base impedance
> on the order of 20 ohms. This tells us that direct
> connection of a 50 ohm coax feed line will produce
> a best SWR of at least 2:1 that rises either side
> of resonance for the antenna.
>
> Many VHF/UHF antennas seen on the ground feature drooping
> radials. Bending the radials downward has a doubly
> beneficial effect. The feed point impedance rises.
> At about 45 degrees of droop, the impedance approaches
> 50 ohms thus providing a better SWR. It also has the
> effect of lowering the radiation angle for the antenna
> thus improving performance for talking/listening to
> stations just above the horizon.
>
> VHF antennas for airplanes are exceedingly limited with
> respect to optimization for lowest SWR. Fortunately,
> VHF communications are light of sight. A few watts and
> a wet string for an antenna will let you talk as far
> as you commonly need to talk . . . a distance that
> seldom extends out the horizon. So the mediocre 1/4-wave
> whisker feed directly with a 50 ohm coax offers
> no observable degradation of performance.
>
> Occasionally, a design goal for a new antenna
> design calls for lower SWR. It may not let you
> talk or listen further, but it does look 'better'
> in the sales literature. A variety of matching
> techniques can be used to bring the load
> impedance of the finished antenna closer to
> that of the feed line. If that network includes
> capacitors . . . it would explain the loss of DC
> continuity from coax center conductor to antenna
> mast. For any such matching circuit to exist,
> there must be a sufficient volume within a base
> fairing to house the components.
>
> I've not seen antennas with matching networks
> crafted with capacitors . . . but it's possible.
> It's also possible that continuity measured from
> center conductor to ground in an inductively compensated
> antenna might approach zero ohms leading the observer
> to think that it's 'shorted'.
>
> Continuity tests for open feed lines are always
> informative. But in cases of confusing ohmmeter
> measurements to the antenna itself, checking the
> SWR of an installed antenna is the true test
> for proper function.
>
>
> Bob . . .
>
>
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! --
|