Today's Message Index:
----------------------
1. 06:23 AM - Re: AEC9001 Schottky diode in Z-13/8 (Eric M. Jones)
2. 06:51 AM - Re: Re: AEC9001 Schottky diode in Z-13/8 (Bill Bradburry)
3. 07:25 AM - Re: Re: AEC9001 Schottky diode in Z-13/8 (Bob McCallum)
4. 07:56 AM - Ground plane for GPS antenna? (MLWynn@aol.com)
5. 08:16 AM - Re: Re: AEC9001 Schottky diode in Z-13/8 (Ed Anderson)
6. 08:39 AM - Re: AEC9001 Schottky diode in Z-13/8 (Eric M. Jones)
7. 08:48 AM - Re: Re: Anti Corrosive Zinc Paste (Robert L. Nuckolls, III)
8. 08:54 AM - Re: Ground plane for GPS antenna? (Robert L. Nuckolls, III)
9. 09:02 AM - Re: Re: AEC9001 Schottky diode in Z-13/8 (Bill Bradburry)
10. 10:04 AM - Klixon CB - split lock washer and how best to secure #6 ring (plevyakh)
11. 10:08 AM - Re: Ground plane for GPS antenna? (jason@jasonbeaver.com)
12. 10:11 AM - Re: Klixon CB - split lock washer and how best to secure #6 ring (bobsv35b@aol.com)
13. 10:22 AM - Re: Ground plane for GPS antenna? (bobsv35b@aol.com)
14. 10:44 AM - Re: Ground plane for GPS antenna? (MLWynn@aol.com)
15. 10:44 AM - Re: Ground plane for GPS antenna? (jason@jasonbeaver.com)
16. 11:32 AM - Re: Ground plane for GPS antenna? (bobsv35b@aol.com)
Message 1
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| Subject: | Re: AEC9001 Schottky diode in Z-13/8 |
As others have mentioned, the problem is in how you use your tools...like the voltmeter.
Imagine that you have a voltmeter that is infinitely sensitive (infinite impedance).
Now it will measure the battery voltage even thru an open switch. In fact,
it will measure 500 volts between your belt buckle and your shoe laces. And
the top of your hat will be 1000 volts higher than the soles of your New Balance
sneakers. You can actually extract some tiny amount of power this way.
So meter impedance is not a lack of quality in a meter, it is a necessary and useful
characteristic of the measuring device. And in a solid state circuit (like
a diode), there will almost always be a voltage on the output that is similar
to the input voltage even when the meter is off. And in fact the "leakage voltage"
will not be able to light even the tiniest LED...so ignore it.
I once designed a Cmos circuit where somebody (okay, me...) forgot to add the power
trace to the IC. Years later, an inquisitive technician, tracing an unrelated
fault discovered it, but all the shipped product had worked just fine.
So just don't make voltage measurements like this.
See attached for a better way.
--------
Eric M. Jones
www.PerihelionDesign.com
113 Brentwood Drive
Southbridge, MA 01550
(508) 764-2072
emjones(at)charter.net
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=373387#373387
Attachments:
http://forums.matronics.com//files/diode_test_116.pdf
Message 2
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| Subject: | Re: AEC9001 Schottky diode in Z-13/8 |
Eric,
This sounds like the possible explanation for a problem that I solved but
never understood. Still don't... even if this is the explanation! :>)
20 years ago, I had a sprinkler zone that would not come on. I checked
voltage at the solenoid and found 12V, so I assumed that the solenoid was
bad. I replaced it...still didn't work! I then checked the original
solenoid at the control box. It worked! Hmmmm!
I ran new wires out to the valve from the controller box hooked up the
original solenoid and it worked! Problem solved.
I have never understood how I could have 12V at the solenoid and it would
not work. Is this an explanation and if so how??
Bill B
-----Original Message-----
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Eric M.
Jones
Sent: Sunday, May 20, 2012 9:22 AM
Subject: AeroElectric-List: Re: AEC9001 Schottky diode in Z-13/8
<emjones@charter.net>
As others have mentioned, the problem is in how you use your tools...like
the voltmeter.
Imagine that you have a voltmeter that is infinitely sensitive (infinite
impedance). Now it will measure the battery voltage even thru an open
switch. In fact, it will measure 500 volts between your belt buckle and your
shoe laces. And the top of your hat will be 1000 volts higher than the soles
of your New Balance sneakers. You can actually extract some tiny amount of
power this way.
So meter impedance is not a lack of quality in a meter, it is a necessary
and useful characteristic of the measuring device. And in a solid state
circuit (like a diode), there will almost always be a voltage on the output
that is similar to the input voltage even when the meter is off. And in fact
the "leakage voltage" will not be able to light even the tiniest LED...so
ignore it.
I once designed a Cmos circuit where somebody (okay, me...) forgot to add
the power trace to the IC. Years later, an inquisitive technician, tracing
an unrelated fault discovered it, but all the shipped product had worked
just fine.
So just don't make voltage measurements like this.
See attached for a better way.
--------
Eric M. Jones
www.PerihelionDesign.com
113 Brentwood Drive
Southbridge, MA 01550
(508) 764-2072
emjones(at)charter.net
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=373387#373387
Attachments:
http://forums.matronics.com//files/diode_test_116.pdf
Message 3
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| Subject: | Re: AEC9001 Schottky diode in Z-13/8 |
Broken wire, bit of moisture, easily enough to "power" the meter. (Read the
voltage)
No direct connection to actually pass current to power the relatively large
solenoid power requirements.
Bob McC
> -----Original Message-----
> From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-
> server@matronics.com] On Behalf Of Bill Bradburry
> Sent: Sunday, May 20, 2012 9:50 AM
> To: aeroelectric-list@matronics.com
> Subject: RE: AeroElectric-List: Re: AEC9001 Schottky diode in Z-13/8
>
> <bbradburry@bellsouth.net>
>
> Eric,
> This sounds like the possible explanation for a problem that I solved but
> never understood. Still don't... even if this is the explanation! :>)
>
> 20 years ago, I had a sprinkler zone that would not come on. I checked
> voltage at the solenoid and found 12V, so I assumed that the solenoid was
> bad. I replaced it...still didn't work! I then checked the original
> solenoid at the control box. It worked! Hmmmm!
>
> I ran new wires out to the valve from the controller box hooked up the
> original solenoid and it worked! Problem solved.
>
> I have never understood how I could have 12V at the solenoid and it would
> not work. Is this an explanation and if so how??
>
> Bill B
>
> -----Original Message-----
> From: owner-aeroelectric-list-server@matronics.com
> [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Eric M.
> Jones
> Sent: Sunday, May 20, 2012 9:22 AM
> To: aeroelectric-list@matronics.com
> Subject: AeroElectric-List: Re: AEC9001 Schottky diode in Z-13/8
>
> <emjones@charter.net>
>
> As others have mentioned, the problem is in how you use your tools...like
> the voltmeter.
>
> Imagine that you have a voltmeter that is infinitely sensitive (infinite
> impedance). Now it will measure the battery voltage even thru an open
> switch. In fact, it will measure 500 volts between your belt buckle and
your
> shoe laces. And the top of your hat will be 1000 volts higher than the
soles
> of your New Balance sneakers. You can actually extract some tiny amount of
> power this way.
>
> So meter impedance is not a lack of quality in a meter, it is a necessary
> and useful characteristic of the measuring device. And in a solid state
> circuit (like a diode), there will almost always be a voltage on the
output
> that is similar to the input voltage even when the meter is off. And in
fact
> the "leakage voltage" will not be able to light even the tiniest LED...so
> ignore it.
>
> I once designed a Cmos circuit where somebody (okay, me...) forgot to add
> the power trace to the IC. Years later, an inquisitive technician, tracing
> an unrelated fault discovered it, but all the shipped product had worked
> just fine.
>
> So just don't make voltage measurements like this.
>
> See attached for a better way.
>
> --------
> Eric M. Jones
> www.PerihelionDesign.com
> 113 Brentwood Drive
> Southbridge, MA 01550
> (508) 764-2072
> emjones(at)charter.net
>
>
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=373387#373387
>
>
>
>
> Attachments:
>
> http://forums.matronics.com//files/diode_test_116.pdf
>
>
>
>
>
>
>
>
> _-
> ====================================================
> ======
> _-
> ====================================================
> ======
> _-
> ====================================================
> ======
> _-
> ====================================================
> ======
>
>
Message 4
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| Subject: | Ground plane for GPS antenna? |
Hi all,
I am building an RV 8. Per the suggestion of several builders, I make a
bracket to hold my GPS antenna under the cowl, just forward of the firewall.
The bracket is bolted to the firewall. I painted it to match my engine and
plenum. I got to wondering if the paint was an error. I know that the
nav and com antennae don't work without connection to the ground plane of
the aircraft. Is that also true for a GPS antenna? The antenna is the one
that came with a Garmin 430W.
It would be easy enough to buff off the paint where the antenna rests.
The bracket is pretty will grounded to the airframe by its bolts. Would that
suffice for a ground plane if it is needed?
Thanks,
Michael Wynn
RV 8 Finishing
San Ramon, CA
Message 5
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| Subject: | Re: AEC9001 Schottky diode in Z-13/8 |
Bill,
12Volts at the relay could/did exist - but if you did NOT have an adequate
return path (ground) for CURRENT to flow then no current would flow through
the relay, no power to close the relay would develop and nothing would
happen. You must have a path for current flow. So once you took the relay
back and hooked it up to a good ground - it worked.
Voltage is similar to water pressure - you can have 12PSI of water pressure
on one side of a water valve leading to a water turbine - but if you do not
open the valve (provide a path for water flow) then the 12PSI does nothing
for you, no work is produced and the turbine never spins(relay never
closes).
When I was just getting interested in electronics (around 10 years old), I
would go to the local dump and haul out old discarded radios and cut out the
components. I would take a resistor and measure the resistance with an ohm
meter and sure enough the resistance measure was close(more or less) to the
color code on the resistor - so ah, I thought another good one.
Then I would put voltage (12 volts) to one end of the resistor and then
measure the voltage at the other end and much to my puzzlement and dismay -
no voltage was dropped, it still read 12 volts. So the resistor must have
somehow gone bad - but, measured the resistance again and it was on the
money.
Later the light bulb came on - the impedance of the voltmeter was too high
to draw any significant current through the resistor, therefore there was
only a very small (unnoticable to me) voltage drop across the resistor. Of
course once I grounded one end of the resistor then max current would flow
through it and all 12 volts would be dropped across the resistor. Without
current flow through a resistor (V=I*R) there is no voltage dropped across
it and the voltage will measure the same on both ends of the resistor. In
other words if I (current) = 0 then Voltage Drop V = 0 * R = 0 or no voltage
drop.
Ed
--------------------------------------------------
From: "Bill Bradburry" <bbradburry@bellsouth.net>
Sent: Sunday, May 20, 2012 9:50 AM
Subject: RE: AeroElectric-List: Re: AEC9001 Schottky diode in Z-13/8
> <bbradburry@bellsouth.net>
>
> Eric,
> This sounds like the possible explanation for a problem that I solved but
> never understood. Still don't... even if this is the explanation! :>)
>
> 20 years ago, I had a sprinkler zone that would not come on. I checked
> voltage at the solenoid and found 12V, so I assumed that the solenoid was
> bad. I replaced it...still didn't work! I then checked the original
> solenoid at the control box. It worked! Hmmmm!
>
> I ran new wires out to the valve from the controller box hooked up the
> original solenoid and it worked! Problem solved.
>
> I have never understood how I could have 12V at the solenoid and it would
> not work. Is this an explanation and if so how??
>
> Bill B
>
> -----Original Message-----
> From: owner-aeroelectric-list-server@matronics.com
> [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Eric M.
> Jones
> Sent: Sunday, May 20, 2012 9:22 AM
> To: aeroelectric-list@matronics.com
> Subject: AeroElectric-List: Re: AEC9001 Schottky diode in Z-13/8
>
> <emjones@charter.net>
>
> As others have mentioned, the problem is in how you use your tools...like
> the voltmeter.
>
> Imagine that you have a voltmeter that is infinitely sensitive (infinite
> impedance). Now it will measure the battery voltage even thru an open
> switch. In fact, it will measure 500 volts between your belt buckle and
> your
> shoe laces. And the top of your hat will be 1000 volts higher than the
> soles
> of your New Balance sneakers. You can actually extract some tiny amount of
> power this way.
>
> So meter impedance is not a lack of quality in a meter, it is a necessary
> and useful characteristic of the measuring device. And in a solid state
> circuit (like a diode), there will almost always be a voltage on the
> output
> that is similar to the input voltage even when the meter is off. And in
> fact
> the "leakage voltage" will not be able to light even the tiniest LED...so
> ignore it.
>
> I once designed a Cmos circuit where somebody (okay, me...) forgot to add
> the power trace to the IC. Years later, an inquisitive technician, tracing
> an unrelated fault discovered it, but all the shipped product had worked
> just fine.
>
> So just don't make voltage measurements like this.
>
> See attached for a better way.
>
> --------
> Eric M. Jones
> www.PerihelionDesign.com
> 113 Brentwood Drive
> Southbridge, MA 01550
> (508) 764-2072
> emjones(at)charter.net
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=373387#373387
>
>
> Attachments:
>
> http://forums.matronics.com//files/diode_test_116.pdf
>
>
> -----
> No virus found in this message.
> Checked by AVG - www.avg.com
>
Message 6
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| Subject: | Re: AEC9001 Schottky diode in Z-13/8 |
Bill B.:
Hard to know. But the lesson is that a voltmeter should never, and I mean NEVER
be used as a makeshift continuity tester. A 12V indicator lamp is a much better
tool.
I used to know an 85-year old electrician nicknamed Sparky (really) who told me
that in the early days they never used meters, he would just put his two fingers
across the line (even 440V!). But there was a technique to it--one finger
on the hot and one on the ground or neutral AT THE SAME INSTANT--And don't touch
anything else. Same when removing them. It is easy to do this with 12V, but
you have to lick your fingers and press hard. Every kid knows you can test a
9V battery on your tongue and a 1.5V cell can be tested UNDER the tongue.
--------
Eric M. Jones
www.PerihelionDesign.com
113 Brentwood Drive
Southbridge, MA 01550
(508) 764-2072
emjones(at)charter.net
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=373400#373400
Message 7
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| Subject: | Re: Anti Corrosive Zinc Paste |
>There are several posts from people about this, and I see two more
>that I haven't read. Let me see what they say and hopefully one of
>them will stand out on a recommended good grease at a good price and
>readily available.
I would suggest the use of ductile sealants on joints that
are exposed to most severe combinations of contaminants+water+
heat. Battery terminals come to mind. Joints that are made up
once and expected to run the lifetime of the airplane (crimped
terminals, fat-wire connections to accessories, busses, etc)
and not splashed or gassed are generally fine without added
insurance.
While I was working at Cessna, I recall an optional 'corrosion
resistant' treatment that was offered to individuals who lived
on the coasts, and owners of planes on floats or agricultural
spray planes. Over the years, there have been numerous spray-
on treatments for the interior surfaces of aluminum airplanes
with a notion of slowing corrosion. But all of these offsets
were directed at structural corrosion issues as opposed to
the make up of a joint between two conductors in the electrical
system.
Intrusion of conductive moisture is antagonistic to the
copper/aluminum joint right at the edges of the joint. Usually
right under the terminal flag, out of sight but also not gas-
tight to the environment.
Emacs!
For all the concerns about fending off oxidation of metals
on the aircraft structure, I don't recall ever reading about
a generalized treatment of electrical components beyond the
use of tin plated terminals to take a ground wire down to
an aluminum skin. The value of this process is illustrated
here:
Emacs!
Adding the layer of tin to the copper by plating insures
gas-tightness between the copper and tin but the mechanical
limitations of getting gas tightness between tin and aluminum
are unchanged . . . the advantage of this process is that the
Seebeck voltage developed between aluminum-tin thermocouple
is lower than aluminum-copper . . . hence the rate of corrosion
in the presence of dirty moisture is reduced. It's still not
zero but it is smaller. Virtually any, viscous, non-conductive
material in this space is an effective deterrent to the ingress
of dirty moisture.
For the most part, getting excited to action for the purpose
of preserving one's electrical joints has a poor return on
investment. I've never seen a callout on a production airplane
drawing for any form of guckem to be applied between electrical
parts before mating.
Cost of ownership risks are much greater for other members of
the family of attackers. I've seen devastating effects on the
tailcone of a nice ol' C-140 where colonies of mice took up
residence. That was the only airplane I ever thought about
buying and refurbishing . . . until I looked behind the
seats. Even the bulkhead flanges had big holes in them.
Bob . . .
Message 8
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| Subject: | Re: Ground plane for GPS antenna? |
At 09:55 AM 5/20/2012, you wrote:
>Hi all,
>
>I am building an RV 8. Per the suggestion of several builders, I
>make a bracket to hold my GPS antenna under the cowl, just forward
>of the firewall. The bracket is bolted to the firewall. I painted
>it to match my engine and plenum. I got to wondering if the paint
>was an error. I know that the nav and com antennae don't work
>without connection to the ground plane of the aircraft. Is that
>also true for a GPS antenna? The antenna is the one that came with
>a Garmin 430W.
>
>It would be easy enough to buff off the paint where the antenna
>rests. The bracket is pretty will grounded to the airframe by its
>bolts. Would that suffice for a ground plane if it is needed?
>
>Thanks,
>
>Michael Wynn
>RV 8 Finishing
>San Ramon, CA
>
GPS antennas do not generally rely on any sort of
ground plane provided by surrounding support structure.
The little flat GPS antennas are generally of the
"patch" variety. See:
http://home.iae.nl/users/plundahl/antenne/patchant.htm
So paint UNDER the antenna is of no significance. Paint
over the antenna MIGHT be significant.
Bob . . .
Message 9
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| Subject: | Re: AEC9001 Schottky diode in Z-13/8 |
So you guys now know why, as an electrician, I am a middling carpenter!
Bill B
-----Original Message-----
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Eric M.
Jones
Sent: Sunday, May 20, 2012 11:38 AM
Subject: AeroElectric-List: Re: AEC9001 Schottky diode in Z-13/8
<emjones@charter.net>
Bill B.:
Hard to know. But the lesson is that a voltmeter should never, and I mean
NEVER be used as a makeshift continuity tester. A 12V indicator lamp is a
much better tool.
I used to know an 85-year old electrician nicknamed Sparky (really) who told
me that in the early days they never used meters, he would just put his two
fingers across the line (even 440V!). But there was a technique to it--one
finger on the hot and one on the ground or neutral AT THE SAME INSTANT--And
don't touch anything else. Same when removing them. It is easy to do this
with 12V, but you have to lick your fingers and press hard. Every kid knows
you can test a 9V battery on your tongue and a 1.5V cell can be tested UNDER
the tongue.
--------
Eric M. Jones
www.PerihelionDesign.com
113 Brentwood Drive
Southbridge, MA 01550
(508) 764-2072
emjones(at)charter.net
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=373400#373400
Message 10
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| Subject: | Klixon CB - split lock washer and how best to secure |
#6 ring
Guys,
Searching the archives I couldn't locate tips on how best to secure the threaded
fasteners for the switches and Klixon CBs that don't use FASTON tabs.
For example the two Klixon 7277-1-5 CB (5amp) used for the alternator fields use
a #6 screw with a split ring lock washer.
What's the best way to secure the wire ring connector to ensure it doesn't vibrate
loose? Thread sealant?
Thanks,
Howard
(GlaStar in Cincinnati, OH)
--------
Howard Plevyak
GlaStar / North Bend, Ohio
hplevyak@mac.com
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=373408#373408
Message 11
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| Subject: | Re: Ground plane for GPS antenna? |
The install manual for my Garmin GTN-635 specified that the antenna be
grounded to the airframe and have a minimum of 7.5 radius around the
perimeter. Here's an excerpt from the manual:
2.5.5 Ground Plane
Ensure that the GPS/NAV/COM antennas are electrically bonded to the
aircraft. Follow the aircraft manufacturers=98 instructions for the N
AV and
COM antenna installations, or obtain other FAA approval.
The GPS/WAAS antenna requires a minimum ground plane radius of 7.5 inches
around the perimeter of the antenna. Refer to Figure 2-10. For metal
aircraft, the surrounding metal skin on which the antenna is mounted
supplies the ground plane. For non-metal aircraft, the ground plane can be
composed of heavy duty aluminum foil tape, such as 3M P/N 438 or other
adhesive backed dead soft aluminum foil minimum 0.012 inches thick. It
should be noted that if the antenna is struck by lightning, the foil by
itself may not be sufficient to dissipate lightning currents. Additional
protection may be needed depending on the construction of the structure to
which the antenna is mounted.
jason
On May 20, 2012 at 11:53 AM "Robert L. Nuckolls, III"
<nuckolls.bob@aeroelectric.com> wrote:
> At 09:55 AM 5/20/2012, you wrote:
> >Hi all,
> >
> >I am building an RV 8. Per the suggestion of several builders, I
> >make a bracket to hold my GPS antenna under the cowl, just forward
> >of the firewall. The bracket is bolted to the firewall. I painted
> >it to match my engine and plenum. I got to wondering if the paint
> >was an error. I know that the nav and com antennae don't work
> >without connection to the ground plane of the aircraft. Is that
> >also true for a GPS antenna? The antenna is the one that came with
> >a Garmin 430W.
> >
> >It would be easy enough to buff off the paint where the antenna
> >rests. The bracket is pretty will grounded to the airframe by its
> >bolts. Would that suffice for a ground plane if it is needed?
> >
> >Thanks,
> >
> >Michael Wynn
> >RV 8 Finishing
> >San Ramon, CA
> >
>
> GPS antennas do not generally rely on any sort of
> ground plane provided by surrounding support structure.
> The little flat GPS antennas are generally of the
> "patch" variety. See:
>
> http://home.iae.nl/users/plundahl/antenne/patchant.htm
>
> So paint UNDER the antenna is of no significance. Paint
> over the antenna MIGHT be significant.
>
> Bob . . .
Message 12
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| Subject: | Re: Klixon CB - split lock washer and how best to secure |
#6 ring
Good Afternoon Howard,
All I have ever done is use the screw and washer provided for that purpose.
It does help a lot to make a harness of the wires so that they are not pro
viding a strain on the joint which may tend to loosen the connection. Screw
s with washers have done the job quite well in production aircraft for at l
east sevent-five years or more. Why try to reinvent the wheel?
Happy Skies,
Old Bob
-----Original Message-----
From: plevyakh <hplevyak@mac.com>
Sent: Sun, May 20, 2012 12:05 pm
Subject: AeroElectric-List: Klixon CB - split lock washer and how best to s
ecure #6 ring
Guys,
Searching the archives I couldn't locate tips on how best to secure the thr
eaded
fasteners for the switches and Klixon CBs that don't use FASTON tabs.
For example the two Klixon 7277-1-5 CB (5amp) used for the alternator field
s use
a #6 screw with a split ring lock washer.
What's the best way to secure the wire ring connector to ensure it doesn't
vibrate loose? Thread sealant?
Thanks,
Howard
(GlaStar in Cincinnati, OH)
--------
Howard Plevyak
GlaStar / North Bend, Ohio
hplevyak@mac.com
Message 13
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| Subject: | Re: Ground plane for GPS antenna? |
Good Afternoon Jason,
I think if you read between the lines you will see that the concern is for
static build up or lightning strike considerations.
The antenna will work just fine as long as it is NOT in a major shadow of a
large component of the metallic airframe with no connection to the airfram
e at all. The bonding and grounding of the antenna, unlike a normal comm an
tenna, has nothing to do with it's efficiency as an antenna.
Make any sense at all?
Happy Skies,
Old Bob
Downers Grove, IL
-----Original Message-----
From: jason <jason@jasonbeaver.com>
Sent: Sun, May 20, 2012 12:09 pm
Subject: Re: AeroElectric-List: Ground plane for GPS antenna?
The install manual for my Garmin GTN-635 specified that the antenna
be grounded to the airframe and have a minimum of 7.5 radius around the per
imeter. Here's an excerpt from the manual:
2.5.5 Ground Plane
Ensure that the GPS/NAV/COM antennas are electrically bonded to the air
craft. Follow the aircraft manufacturers=98 instructions for the NAV
and COM antenna installations, or obtain other FAA approval.
The GPS/WAAS antenna requires a minimum ground plane radius of 7.5 inch
es around the perimeter of the antenna. Refer to Figure 2-10. For metal air
craft, the surrounding metal skin on which the antenna is mounted supplies
the ground plane. For non-metal aircraft, the ground plane can be composed
of heavy duty aluminum foil tape, such as 3M P/N 438 or other adhesive back
ed dead soft aluminum foil minimum 0.012 inches thick. It should be noted t
hat if the antenna is struck by lightning, the foil by itself may not be su
fficient to dissipate lightning currents. Additional protection may be need
ed depending on the construction of the structure to which the antenna is m
ounted.
jason
On May 20, 2012 at 11:53 AM "Robert L. Nuckolls, III" <nuckolls.bob@aero
electric.com> wrote:
> At 09:55 AM 5/20/2012, you wrote:
> >Hi all,
> >
> >I am building an RV 8. Per the suggestion of several builders, I
> >make a bracket to hold my GPS antenna under the cowl, just forward
> >of the firewall. The bracket is bolted to the firewall. I painted
> >it to match my engine and plenum. I got to wondering if the paint
> >was an error. I know that the nav and com antennae don't work
> >without connection to the ground plane of the aircraft. Is that
> >also true for a GPS antenna? The antenna is the one that came with
> >a Garmin 430W.
> >
> >It would be easy enough to buff off the paint where the antenna
> >rests. The bracket is pretty will grounded to the airframe by its
> >bolts. Would that suffice for a ground plane if it is needed?
> >
> >Thanks,
> >
> >Michael Wynn
> >RV 8 Finishing
> >San Ramon, CA
> >
>
> GPS antennas do not generally rely on any sort of
> ground plane provided by surrounding support structure.
> The little flat GPS antennas are generally of the
> "patch" variety. See:
>
> http://home.iae.nl/users/plundahl/antenne/patchant.htm
>
> So paint UNDER the antenna is of no significance. Paint
> over the antenna MIGHT be significant.
>
> Bob . . .
Message 14
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| Subject: | Re: Ground plane for GPS antenna? |
Thanks, guys. Now I can leave my nice paint job intact.
Regards,
Michael Wynn
RV 8 Finishing
San Ramon, CA
In a message dated 5/20/2012 10:22:52 A.M. Pacific Daylight Time,
bobsv35b@aol.com writes:
Good Afternoon Jason,
I think if you read between the lines you will see that the concern is for
static build up or lightning strike considerations.
The antenna will work just fine as long as it is NOT in a major shadow of
a large component of the metallic airframe with no connection to the
airframe at all. The bonding and grounding of the antenna, unlike a normal
comm
antenna, has nothing to do with it's efficiency as an antenna.
Make any sense at all?
Happy Skies,
Old Bob
Downers Grove, IL
-----Original Message-----
From: jason <jason@jasonbeaver.com>
Sent: Sun, May 20, 2012 12:09 pm
Subject: Re: AeroElectric-List: Ground plane for GPS antenna?
The install manual for my Garmin GTN-635 specified that the antenna be
grounded to the airframe and have a minimum of 7.5 radius around the
perimeter. Here's an excerpt from the manual:
2.5.5 Ground Plane
Ensure that the GPS/NAV/COM antennas are electrically bonded to the
aircraft. Follow the aircraft manufacturers=98 instructions for the
NAV and COM
antenna installations, or obtain other FAA approval.
The GPS/WAAS antenna requires a minimum ground plane radius of 7.5 inches
around the perimeter of the antenna. Refer to Figure 2-10. For metal
aircraft, the surrounding metal skin on which the antenna is mounted suppl
ies the
ground plane. For non-metal aircraft, the ground plane can be composed of
heavy duty aluminum foil tape, such as 3M P/N 438 or other adhesive backed
dead soft aluminum foil minimum 0.012 inches thick. It should be noted tha
t
if the antenna is struck by lightning, the foil by itself may not be
sufficient to dissipate lightning currents. Additional protection may be n
eeded
depending on the construction of the structure to which the antenna is
mounted.
jason
On May 20, 2012 at 11:53 AM "Robert L. Nuckolls, III"
<_nuckolls.bob@aeroelectric.com_ (mailto:nuckolls.bob@aeroelectric.com) >
wrote:
> At 09:55 AM 5/20/2012, you wrote:
> >Hi all,
> >
> >I am building an RV 8. Per the suggestion of several builders, I
> >make a bracket to hold my GPS antenna under the cowl, just forward
> >of the firewall. The bracket is bolted to the firewall. I painted
> >it to match my engine and plenum. I got to wondering if the paint
> >was an error. I know that the nav and com antennae don't work
> >without connection to the ground plane of the aircraft. Is that
> >also true for a GPS antenna? The antenna is the one that came with
> >a Garmin 430W.
> >
> >It would be easy enough to buff off the paint where the antenna
> >rests. The bracket is pretty will grounded to the airframe by its
> >bolts. Would that suffice for a ground plane if it is needed?
> >
> >Thanks,
> >
> >Michael Wynn
> >RV 8 Finishing
> >San Ramon, CA
> >
>
> GPS antennas do not generally rely on any sort of
> ground plane provided by surrounding support structure.
> The little flat GPS antennas are generally of the
> "patch" variety. See:
>
> _http://home.iae.nl/users/plundahl/antenne/patchant.htm_
(http://home.iae.nl/users/plundahl/antenne/patchant.htm)
>
> So paint UNDER the antenna is of no significance. Paint
> over the antenna MIGHT be significant.
>
> Bob . . .
ist" target="_blank">http://www.matronics.com/Navigator?AeroElectric-Lis
t
tp://forums.matronics.com _blank">http://www.matronics.com/contribution
(http://www.matronics.com/Navigator?AeroElectric-List)
(http://www.matronics.com/contribution)
Message 15
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| Subject: | Re: Ground plane for GPS antenna? |
Hi Bob,
I don't think you can infer that their concern is lightning strike
protection since they specify that a foil ground plane be installed on
non-metal aircraft and then go on to state that the foil may not be
sufficient to dissipate lightning currents. The inference is that the
ground plane is improving its efficiency as an antenna.
jason
On May 20, 2012 at 1:21 PM bobsv35b@aol.com wrote:
>
> Good Afternoon Jason,
>
> I think if you read between the lines you will see that the concern is
for static build up or lightning strike considerations.
>
> The antenna will work just fine as long as it is NOT in a major shadow of
a large component of the metallic airframe with no connection to the
airframe at all. The bonding and grounding of the antenna, unlike a normal
comm antenna, has nothing to do with it's efficiency as an antenna.
>
> Make any sense at all?
>
> Happy Skies,
>
> Old Bob
> Downers Grove, IL
>
>
> -----Original Message-----
> From: jason <jason@jasonbeaver.com>
> To: aeroelectric-list <aeroelectric-list@matronics.com>
> Sent: Sun, May 20, 2012 12:09 pm
> Subject: Re: AeroElectric-List: Ground plane for GPS antenna?
>
>
>
> The install manual for my Garmin GTN-635 specified that the
antenna be grounded to the airframe and have a minimum of 7.5 radius around
the perimeter. Here's an excerpt from the manual:
>
> 2.5.5 Ground Plane
>
> Ensure that the GPS/NAV/COM antennas are electrically bonded to the
aircraft. Follow the aircraft manufacturers=98 instructions for the N
AV and
COM antenna installations, or obtain other FAA approval.
>
> The GPS/WAAS antenna requires a minimum ground plane radius of 7.5
inches around the perimeter of the antenna. Refer to Figure 2-10. For metal
aircraft, the surrounding metal skin on which the antenna is mounted
supplies the ground plane. For non-metal aircraft, the ground plane can be
composed of heavy duty aluminum foil tape, such as 3M P/N 438 or other
adhesive backed dead soft aluminum foil minimum 0.012 inches thick. It
should be noted that if the antenna is struck by lightning, the foil by
itself may not be sufficient to dissipate lightning currents. Additional
protection may be needed depending on the construction of the structure to
which the antenna is mounted.
>
> jason
>
>
>
> On May 20, 2012 at 11:53 AM "Robert L. Nuckolls, III"
<nuckolls.bob@aeroelectric.com> wrote:
>
> > At 09:55 AM 5/20/2012, you wrote:
> > >Hi all,
> > >
> > >I am building an RV 8. Per the suggestion of several builders, I
> > >make a bracket to hold my GPS antenna under the cowl, just forward
> > >of the firewall. The bracket is bolted to the firewall. I painted
> > >it to match my engine and plenum. I got to wondering if the paint
> > >was an error. I know that the nav and com antennae don't work
> > >without connection to the ground plane of the aircraft. Is that
> > >also true for a GPS antenna? The antenna is the one that came with
> > >a Garmin 430W.
> > >
> > >It would be easy enough to buff off the paint where the antenna
> > >rests. The bracket is pretty will grounded to the airframe by its
> > >bolts. Would that suffice for a ground plane if it is needed?
> > >
> > >Thanks,
> > >
> > >Michael Wynn
> > >RV 8 Finishing
> > >San Ramon, CA
> > >
> >
> > GPS antennas do not generally rely on any sort of
> > ground plane provided by surrounding support structure.
> > The little flat GPS antennas are generally of the
> > "patch" variety. See:
> >
> > http://home.iae.nl/users/plundahl/antenne/patchant.htm
> >
> > So paint UNDER the antenna is of no significance. Paint
> > over the antenna MIGHT be significant.
> >
> > Bob . . .
>
>
Message 16
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|
| Subject: | Re: Ground plane for GPS antenna? |
Good Afternoon Jason,
Since I have no idea what they were trying to handle, I cannot say that you
r thoughts are incorrect. However, my feeling is that the foil is an effort
to better distribute static build up on the airframe.
As a WAG, I would think that having the antenna not well grounded to the ai
rframe could mean that more corrosion could develop where the antenna meets
the airframe. Still no effect on the signal until such time as the integri
ty of the component is compromised. Once again, that is an area in which I
have NO technical knowledge.
My experience with a whole lot of different GPS antennas has been that no g
round plane has any effect, positive or negative, on the performance of a G
PS antenna. My knowledge of radio frequencies is nil. Just a lot of actual
practical observation of results and a very small appreciation of the very
short wave lengths involved.
I should also add that for lightning to actually strike an airplane is an a
lmost implausible event. What we normally call a lightning strike is actual
ly a massive discharge of static electricity. A whole lot of static electri
city could interfere with any radio wave reception.
Happy Skies,
Old Just an Observer, not an Engineer, Bob
-----Original Message-----
From: jason <jason@jasonbeaver.com>
Sent: Sun, May 20, 2012 12:46 pm
Subject: Re: AeroElectric-List: Ground plane for GPS antenna?
Hi Bob,
I don't think you can infer that their concern is lightning strike p
rotection since they specify that a foil ground plane be installed on non-m
etal aircraft and then go on to state that the foil may not be sufficien
t to dissipate lightning currents. The inference is that the ground plane
is improving its efficiency as an antenna.
jason
On May 20, 2012 at 1:21 PM bobsv35b@aol.com wrote:
>
> Good Afternoon Jason,
>
> I think if you read between the lines you will see that the concern is
for static build up or lightning strike considerations.
>
> The antenna will work just fine as long as it is NOT in a major shadow
of a large component of the metallic airframe with no connection to the ai
rframe at all. The bonding and grounding of the antenna, unlike a normal co
mm antenna, has nothing to do with it's efficiency as an antenna.
>
> Make any sense at all?
>
> Happy Skies,
>
> Old Bob
> Downers Grove, IL
>
>
> -----Original Message-----
> From: jason <jason@jasonbeaver.com>
> To: aeroelectric-list <aeroelectric-list@matronics.com>
> Sent: Sun, May 20, 2012 12:09 pm
> Subject: Re: AeroElectric-List: Ground plane for GPS antenna?
>
>
>
> The install manual for my Garmin GTN-635 specified that the ant
enna be grounded to the airframe and have a minimum of 7.5 radius around th
e perimeter. Here's an excerpt from the manual:
>
> 2.5.5 Ground Plane
>
> Ensure that the GPS/NAV/COM antennas are electrically bonded to th
e aircraft. Follow the aircraft manufacturers=98 instructions for the
NAV and COM antenna installations, or obtain other FAA approval.
>
> The GPS/WAAS antenna requires a minimum ground plane radius of 7.5
inches around the perimeter of the antenna. Refer to Figure 2-10. For meta
l aircraft, the surrounding metal skin on which the antenna is mounted supp
lies the ground plane. For non-metal aircraft, the ground plane can be comp
osed of heavy duty aluminum foil tape, such as 3M P/N 438 or other adhesive
backed dead soft aluminum foil minimum 0.012 inches thick. It should be no
ted that if the antenna is struck by lightning, the foil by itself may not
be sufficient to dissipate lightning currents. Additional protection may be
needed depending on the construction of the structure to which the antenna
is mounted.
>
> jason
>
>
>
> On May 20, 2012 at 11:53 AM "Robert L. Nuckolls, III" <nuckolls.bob
@aeroelectric.com> wrote:
>
> > At 09:55 AM 5/20/2012, you wrote:
> > >Hi all,
> > >
> > >I am building an RV 8. Per the suggestion of several builders,
I
> > >make a bracket to hold my GPS antenna under the cowl, just forwa
rd
> > >of the firewall. The bracket is bolted to the firewall. I paint
ed
> > >it to match my engine and plenum. I got to wondering if the pai
nt
> > >was an error. I know that the nav and com antennae don't work
> > >without connection to the ground plane of the aircraft. Is that
> > >also true for a GPS antenna? The antenna is the one that came w
ith
> > >a Garmin 430W.
> > >
> > >It would be easy enough to buff off the paint where the antenna
> > >rests. The bracket is pretty will grounded to the airframe by i
ts
> > >bolts. Would that suffice for a ground plane if it is needed?
> > >
> > >Thanks,
> > >
> > >Michael Wynn
> > >RV 8 Finishing
> > >San Ramon, CA
> > >
> >
> > GPS antennas do not generally rely on any sort of
> > ground plane provided by surrounding support structure.
> > The little flat GPS antennas are generally of the
> > "patch" variety. See:
> >
> > http://home.iae.nl/users/plundahl/antenne/patchant.htm ;
> >
> > So paint UNDER the antenna is of no significance. Paint
> > over the antenna MIGHT be significant.
> >
> > Bob . . .
>
>
>
>
>
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