Today's Message Index:
----------------------
1. 01:41 AM - Re: Radio Master Switch (Werner Schneider)
2. 05:39 AM - Re: Trim on e-buss? (willfly)
3. 06:59 AM - Re: 10204 Simpkins (Robert L. Nuckolls, III)
4. 07:05 AM - Re: Trim on e-buss? (Robert L. Nuckolls, III)
5. 07:46 AM - (Gary Casey)
6. 07:46 AM - Avionics Masters (Gary Casey)
7. 08:18 AM - Re: Dual regulator OV protection (David Swartzendruber)
8. 08:27 AM - Re: GPS antenna (Robert L. Nuckolls, III)
9. 08:29 AM - Re: 10198 Clabots (Robert L. Nuckolls, III)
10. 09:29 AM - Re: Antenna Electronics (Robert L. Nuckolls, III)
11. 09:31 AM - Need some help . . . (Robert L. Nuckolls, III)
12. 09:39 AM - Re: Emp wire bundle (Robert L. Nuckolls, III)
13. 10:20 AM - Re: Perm magnet alternator & fuel pump (Robert L. Nuckolls, III)
14. 10:24 AM - Re: Re: AeroElectric-Pulse charger (Robert L. Nuckolls, III)
15. 10:56 AM - Re: Avionics Masters (Walter Casey)
16. 11:02 AM - Re: Antenna Electronics (John Rourke)
17. 11:37 AM - Re: Antenna Electronics (David Lundquist)
18. 11:38 AM - Re: Antenna Electronics (SportAV8R@aol.com)
19. 11:42 AM - Re: Antenna Electronics (Robert L. Nuckolls, III)
20. 11:45 AM - Re: Avionics Masters (Robert L. Nuckolls, III)
21. 11:57 AM - Re: Antenna Electronics (MATTHEW PRATHER)
22. 12:20 PM - Re: Antenna Electronics (Cy Galley)
23. 12:27 PM - Re: Avionics Masters (Cy Galley)
24. 12:47 PM - Re: Antenna Electronics (Rod Kimmell)
25. 01:07 PM - Re: Radio Master Switch (Robert L. Nuckolls, III)
26. 01:13 PM - Good price on battery tester (Robert L. Nuckolls, III)
27. 01:42 PM - Re: Good price on battery tester (BobsV35B@aol.com)
28. 01:55 PM - Dead Dimmer? (John Slade)
29. 06:17 PM - Re: Dead Dimmer? (Robert L. Nuckolls, III)
30. 06:18 PM - Re: Good price on battery tester (Robert L. Nuckolls, III)
31. 06:53 PM - Re: Avionics Masters (Robert L. Nuckolls, III)
32. 06:57 PM - Re: Dead Dimmer? (John Schroeder)
33. 07:19 PM - CESSNA Cardinal NO AVIONICS MASTER (Don Boardman)
34. 07:38 PM - Re: Dead Dimmer? (John Slade)
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| Subject: | Re: 10198 Clabots |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <bob.nuckolls@cox.net>
At 06:59 PM 1/4/2003 -0800, you wrote:
>Below is the result of your inquiry. It was submitted by
>Gerald Clabots (gclabots@execpc.com) on Saturday, January 4, 2003 at 18:59:39
>
>Saturday, January 4, 2003
>
>Gerald Clabots
>
>,
>Email: gclabots@execpc.com
>Comments/Questions: I plan on ordering you fuse block and fuses, My
>question is my pitot tube draws 8.5 amps. Is a 10 amp fuse to small? That
>would be 85% of rating. What is a recommended loading of fuses?
Pitot heaters are unique in that they have a rather long duration
warm-up inrush current. For an 8A pitot heater, I would fuse it
at 15A and wire the circuit with 14AWG wire. Every other
system in the airplane will be fine with a fuse rated only
slightly higher than running current for the device.
>Thanks
>Gerry
Bob . . .
|-------------------------------------------------------|
| The man who does not read good books has no advantage |
| over the man who cannot read them. |
| - Mark Twain |
|-------------------------------------------------------|
Message 10
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| Subject: | Re: Antenna Electronics |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <bob.nuckolls@cox.net>
At 09:37 PM 1/4/2003 -0500, you wrote:
>--> AeroElectric-List message posted by: "Duane Bentley" <dbentley@fuse.net>
>
>Maybe I have some new, defective antennas or I don't understand the
>electronics. I've read Bob's chapter on antenna theory, but don't readily
>see the answer to my questions.
>
>I'm installing the various nav & com antennas on my RV6 and decided to do a
>continuity check on them before connecting the cables. On the Aeroelectric
>transponder antenna, at the connector, the inner pin is insulated from the
>outer, and the inner has continuity with the shaft, all as I would expect.
>
>On my Comant VOR/LOC/GS cat wiskers, the ohm meter says the inner pin and
>outer connector are hooked together somewhere inside and have complete
>continuity, but the two "whiskers" are insulated from everything.
>
>The Comant marker beacon antenna also has continuity between the inner pin
>and the outer connector shell, but the actual antenna is buried inside the
>housing and I can't check that out.
>
>The bent whip Com antenna is different from the rest. The inner pin and
>outer shell are insulated from each other, but there is also no continuity
>between the inner pin and the whip.
>
>So, are the electronics correct, or do I have some defective antenna?
As a general rule, antennas cannot always be "tested" with an ohmmeter.
Some antennas may have matching networks consisting of various
inductors and capacitors that will make continuity measurements
confusing or meaningless. Active testing by exciting the antenna
with a source at the frequency of interest and measuring resistive
and reactive components (SWR) is the only effective means for
testing an antenna.
As a general rule also, antennas are quite rugged. I cannot
recall ever having to replace an antenna that did not suffer
some catastrophic damage (collision, lighting stroke, etc).
So if your coax feedlines check out, go ahead and stick everything
together. If you find performance lacking after every thing is installed,
it is MORE likely that you have a problem with a radio but it's
easy to test the antenna as installed with test equipment that
will be in the possession of every decent avionics shop.
Bob . . .
Message 11
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| Subject: | Need some help . . . |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <bob.nuckolls@cox.net>
We've set a date for the annual weekend seminar in Ft. Worth.
It's a rather short coupled date (Mar 22/23). I'd really
appreciate it if folks who frequent other list servers would
make an announcement for me (assuming list-manager would not
dis-approve).
Link to the Ft. Worth page is
http://www.aeroelectric.com/seminars/Ft.Worth.html
Thanks guys . . .
Bob . . .
|-------------------------------------------------------|
| The man who does not read good books has no advantage |
| over the man who cannot read them. |
| - Mark Twain |
|-------------------------------------------------------|
Message 12
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| Subject: | Re: Emp wire bundle |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <bob.nuckolls@cox.net>
At 12:02 AM 1/5/2003 -0500, you wrote:
>--> AeroElectric-List message posted by: "Larry Bowen" <Larry@BowenAero.com>
>
>I have wire runs going to the empannage area for three things: trim
>servo, Pointer ELT, and rudder position/strobe combo light. The ELT and
>strobe wires are shielded. (The ELT itself and its antennea are both
>beneath the VS.)
>
>Should there be any problems bundling all three of these wire runs
>together?
>
>-
Risks are quite low . . .
Bob . . .
Message 13
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| Subject: | Re: Perm magnet alternator & fuel pump |
trouble
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <bob.nuckolls@cox.net>
At 09:10 AM 1/3/2003 -0500, you wrote:
>--> AeroElectric-List message posted by: DHPHKH@aol.com
>
><<I suspect the pump (which I believe is solid state electronics to control
>motor coil) may be sensitive to the severe ripple voltage that is present
>with the permanent alternators. >>
>
> Bob, can you expand on the subject of PM alternator ripple? Didn't
>realize that, nor the part about an old battery not being able to smooth
>things for the system.
>
>
>Thanks
>Dan
PM alternators in general are single phase devices with
an unfiltered ripple voltage equal to full output from the
device. 3-phase alternators on the other hand have only
about 5% pk-pk ripple after rectification.
All of our diagrams show a hefty filter capacitor on
each PM alternator installation . . . which should be
replaced every 4-5 years. We also recommend periodic
battery replacement for the purposes of maintaining
both battery capacity and battery filtering effectiveness.
Bob . . .
Message 14
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| Subject: | Re: AeroElectric-Pulse charger |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <bob.nuckolls@cox.net>
At 07:02 AM 1/3/2003 -0800, you wrote:
>--> AeroElectric-List message posted by: "Jim Robinson"
><jbr@hitechnetworks.net>
>
>Bob
>There was a thread awhile back on battery chargers that helped
>desulfonate a battery to prolong it's life. I wonder what was found
>out regarding the units. Do they work as stated? Are they worth
>buying? any suggestions as to brands/ sources?
>Jim Robinson
>Glasair 79R
I have a sample product that's supposed to recover
lost capacity in a battery due to sulfation . . . the
limited testing I've been able to conduct haven't been
conclusive in support of the claims. I wasn't able
to recover a battery that was pulled from service
after it failed to start a car . . . I did see some
increase in battery capacity for a few cycles of testing.
I let the battery sit on the shelf for a month with the
de-sulfater installed . . . took it down and attempted
to charge and retest . . . battery wouldn't accept any
significant charge and it's capacity had dropped to
a few percent of new.
If it were my airplane, I'd still have to opt for
the new-battery-every-year technique for making sure
I was carrying the expected reserve capacity.
Dave S. You guys were looking at some de-sulfator
type products, any new info on that program?
Bob . . .
Message 15
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| Subject: | Re: Avionics Masters |
--> AeroElectric-List message posted by: Walter Casey <mikec@caseyspm.com>
Does anyone remember vacuum tube radios in automobiles. The vacuum
tubes required high voltage (over 90V) and to get this voltage the 6V
DC had to be converted to AC an run through a transformer. The DC to AC
converted was called vibrator and worked like an electric door bell.
When you turned on the radio the first thing you heard was the hum of
the vibrator. The vibrator was quite prone to failure due to contacts
sticking. As I understood it, it was to prevent the contact sticking
that the starter button was removed and replaced by the key
switch/starter which prevented the radio from being on while the car
was started.
Old habits die hard.
Best wishes,
Walter Casey
Message 16
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| Subject: | Re: Antenna Electronics |
--> AeroElectric-List message posted by: John Rourke <jrourke@allied-computer.com>
I would agree that an "open circuit" as shown with an ohmmeter is
entirely possible in a properly functioning antenna, but if it shows a
dead short of 0 ohms from the shielding to the center conductor, I can't
think of any way that antenna could function properly.
If that is the case, I wouldn't want to initiate any transmission test
until the short is found - although I guess today's transceivers can
handle that, it still just doesn't sound like a good idea to me. Am I wrong?
-John R.
P.S.: Other than an RF power/SWR meter, what test equipment ought we to
have to run such tests?
Robert L. Nuckolls, III wrote:
> --> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <bob.nuckolls@cox.net>
>
> At 09:37 PM 1/4/2003 -0500, you wrote:
>
>>--> AeroElectric-List message posted by: "Duane Bentley" <dbentley@fuse.net>
>>
>>Maybe I have some new, defective antennas or I don't understand the
>>electronics. I've read Bob's chapter on antenna theory, but don't readily
>>see the answer to my questions.
>>
>>I'm installing the various nav & com antennas on my RV6 and decided to do a
>>continuity check on them before connecting the cables. On the Aeroelectric
>>transponder antenna, at the connector, the inner pin is insulated from the
>>outer, and the inner has continuity with the shaft, all as I would expect.
>>
>>On my Comant VOR/LOC/GS cat wiskers, the ohm meter says the inner pin and
>>outer connector are hooked together somewhere inside and have complete
>>continuity, but the two "whiskers" are insulated from everything.
>>
>>The Comant marker beacon antenna also has continuity between the inner pin
>>and the outer connector shell, but the actual antenna is buried inside the
>>housing and I can't check that out.
>>
>>The bent whip Com antenna is different from the rest. The inner pin and
>>outer shell are insulated from each other, but there is also no continuity
>>between the inner pin and the whip.
>>
>>So, are the electronics correct, or do I have some defective antenna?
>
>
> As a general rule, antennas cannot always be "tested" with an ohmmeter.
> Some antennas may have matching networks consisting of various
> inductors and capacitors that will make continuity measurements
> confusing or meaningless. Active testing by exciting the antenna
> with a source at the frequency of interest and measuring resistive
> and reactive components (SWR) is the only effective means for
> testing an antenna.
>
> As a general rule also, antennas are quite rugged. I cannot
> recall ever having to replace an antenna that did not suffer
> some catastrophic damage (collision, lighting stroke, etc).
> So if your coax feedlines check out, go ahead and stick everything
> together. If you find performance lacking after every thing is installed,
> it is MORE likely that you have a problem with a radio but it's
> easy to test the antenna as installed with test equipment that
> will be in the possession of every decent avionics shop.
>
> Bob . . .
>
>
>
>
>
>
>
>
Message 17
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| Subject: | Re: Antenna Electronics |
--> AeroElectric-List message posted by: "David Lundquist" <lundquist@ieee.org>
It is entirely possible that a perfectly good antenna can be either open or
a dead short when checked with an ohm meter. The ohm meter is only useful
if you know what the antenna is supposed to be.
Dave Lundquist
lundquist@ieee.org
----- Original Message -----
From: "John Rourke" <jrourke@allied-computer.com>
Subject: Re: AeroElectric-List: Antenna Electronics
> --> AeroElectric-List message posted by: John Rourke
<jrourke@allied-computer.com>
>
> I would agree that an "open circuit" as shown with an ohmmeter is
> entirely possible in a properly functioning antenna, but if it shows a
> dead short of 0 ohms from the shielding to the center conductor, I can't
> think of any way that antenna could function properly.
>
> If that is the case, I wouldn't want to initiate any transmission test
> until the short is found - although I guess today's transceivers can
> handle that, it still just doesn't sound like a good idea to me. Am I
wrong?
>
> -John R.
>
> P.S.: Other than an RF power/SWR meter, what test equipment ought we to
> have to run such tests?
>
>
> Robert L. Nuckolls, III wrote:
> > --> AeroElectric-List message posted by: "Robert L. Nuckolls, III"
<bob.nuckolls@cox.net>
> >
> > At 09:37 PM 1/4/2003 -0500, you wrote:
> >
> >>--> AeroElectric-List message posted by: "Duane Bentley"
<dbentley@fuse.net>
> >>
> >>Maybe I have some new, defective antennas or I don't understand the
> >>electronics. I've read Bob's chapter on antenna theory, but don't
readily
> >>see the answer to my questions.
> >>
> >>I'm installing the various nav & com antennas on my RV6 and decided to
do a
> >>continuity check on them before connecting the cables. On the
Aeroelectric
> >>transponder antenna, at the connector, the inner pin is insulated from
the
> >>outer, and the inner has continuity with the shaft, all as I would
expect.
> >>
> >>On my Comant VOR/LOC/GS cat wiskers, the ohm meter says the inner pin
and
> >>outer connector are hooked together somewhere inside and have complete
> >>continuity, but the two "whiskers" are insulated from everything.
> >>
> >>The Comant marker beacon antenna also has continuity between the inner
pin
> >>and the outer connector shell, but the actual antenna is buried inside
the
> >>housing and I can't check that out.
> >>
> >>The bent whip Com antenna is different from the rest. The inner pin and
> >>outer shell are insulated from each other, but there is also no
continuity
> >>between the inner pin and the whip.
> >>
> >>So, are the electronics correct, or do I have some defective antenna?
> >
> >
> > As a general rule, antennas cannot always be "tested" with an
ohmmeter.
> > Some antennas may have matching networks consisting of various
> > inductors and capacitors that will make continuity measurements
> > confusing or meaningless. Active testing by exciting the antenna
> > with a source at the frequency of interest and measuring resistive
> > and reactive components (SWR) is the only effective means for
> > testing an antenna.
> >
> > As a general rule also, antennas are quite rugged. I cannot
> > recall ever having to replace an antenna that did not suffer
> > some catastrophic damage (collision, lighting stroke, etc).
> > So if your coax feedlines check out, go ahead and stick everything
> > together. If you find performance lacking after every thing is
installed,
> > it is MORE likely that you have a problem with a radio but it's
> > easy to test the antenna as installed with test equipment that
> > will be in the possession of every decent avionics shop.
> >
> > Bob . . .
> >
> >
> >
> >
> >
> >
> >
> >
>
>
Message 18
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| Subject: | Re: Antenna Electronics |
--> AeroElectric-List message posted by: SportAV8R@aol.com
In a message dated 01/07/2003 2:02:30 PM Eastern Standard Time,
jrourke@allied-computer.com writes:
> if it shows a
> dead short of 0 ohms from the shielding to the center conductor, I can't
> think of any way that antenna could function properly.
>
I can: balun transformer between feedline and cat-whiskers. The standard
arrangement, I believe.
Bill B
Message 19
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| Subject: | Re: Antenna Electronics |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <bob.nuckolls@cox.net>
At 12:57 PM 1/7/2003 -0600, you wrote:
>--> AeroElectric-List message posted by: John Rourke
><jrourke@allied-computer.com>
>
>I would agree that an "open circuit" as shown with an ohmmeter is
>entirely possible in a properly functioning antenna, but if it shows a
>dead short of 0 ohms from the shielding to the center conductor, I can't
>think of any way that antenna could function properly.
There are LOTS of antenna designs that measure zero ohms (or
close to it) at the connector that work just fine as an antenna.
The ohmmeter is NOT the tool for antenna testing. . . .
>If that is the case, I wouldn't want to initiate any transmission test
>until the short is found - although I guess today's transceivers can
>handle that, it still just doesn't sound like a good idea to me. Am I wrong?
>
>-John R.
>
>P.S.: Other than an RF power/SWR meter, what test equipment ought we to
>have to run such tests?
An SWR meter is good . . . like
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=4671&item=1949914808
. . . . or an antenna analyzer like
http://www.mfjenterprises.com/products.php?prodid=MFJ-259B
is handy. Perhaps your EAA chapter could purchase one and
rent/loan it to members.
Bob . . .
Message 20
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| Subject: | Re: Avionics Masters |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <bob.nuckolls@cox.net>
At 11:54 AM 1/7/2003 -0700, you wrote:
>--> AeroElectric-List message posted by: Walter Casey <mikec@caseyspm.com>
>
>
>Does anyone remember vacuum tube radios in automobiles. The vacuum
>tubes required high voltage (over 90V) and to get this voltage the 6V
>DC had to be converted to AC an run through a transformer. The DC to AC
>converted was called vibrator and worked like an electric door bell.
>When you turned on the radio the first thing you heard was the hum of
>the vibrator. The vibrator was quite prone to failure due to contacts
>sticking. As I understood it, it was to prevent the contact sticking
>that the starter button was removed and replaced by the key
>switch/starter which prevented the radio from being on while the car
>was started.
>
>Old habits die hard.
My first mobile rig was vibrator power supply powered. Had
it installed in a 6-volt, 1941 Pontiac. Here's some more
info on this bit of ancient but elegant technology at
http://www.geocities.com/vintage_radio/vpwrsup.htm
Bob . . .
Message 21
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| Subject: | Re: Antenna Electronics |
--> AeroElectric-List message posted by: "MATTHEW PRATHER" <mprather@spro.net>
At the risk of being argumentative, and to somewhat amplify on what Bob
said, I believe that an impedance matching balun may be very close to a dc
short across its inputs. Check out http://www.kc7nod.20m.com/new_page_1.htm.
The reason that doesn't damage a transmitter is that the AC impedance of the
inductor will always be greater than the measured DC resistance. What short
circuit protection scheme is designed into the output stage of the
transmitter
shouldn't matter when driving into an inductive load (like a matching
transformer).
I would imagine that your ADF antenna might look like a DC short because of
just such an impedance matcher. This is so because an efficiently sized
dipole
for lower (ADF) frequencies might be quite large. Not relevant example for
transmitter damage, but if you are playing with an ohmeter and your airplane
antennas, don't be surprised...
Regards,
Matt Prather
N34RD
> --> AeroElectric-List message posted by: John Rourke
> <jrourke@allied-computer.com>
>
> I would agree that an "open circuit" as shown with an ohmmeter is
> entirely possible in a properly functioning antenna, but if it shows a
> dead short of 0 ohms from the shielding to the center conductor, I can't
> think of any way that antenna could function properly.
>
> If that is the case, I wouldn't want to initiate any transmission test
> until the short is found - although I guess today's transceivers can
> handle that, it still just doesn't sound like a good idea to me. Am I
> wrong?
>
> -John R.
>
> P.S.: Other than an RF power/SWR meter, what test equipment ought we to
> have to run such tests?
>
>
> Robert L. Nuckolls, III wrote:
>> --> AeroElectric-List message posted by: "Robert L. Nuckolls, III"
>> <bob.nuckolls@cox.net>
>>
>> At 09:37 PM 1/4/2003 -0500, you wrote:
>>
>>>--> AeroElectric-List message posted by: "Duane Bentley"
>>> <dbentley@fuse.net>
>>>
>>>Maybe I have some new, defective antennas or I don't understand the
>>> electronics. I've read Bob's chapter on antenna theory, but don't
>>> readily see the answer to my questions.
>>>
>>>I'm installing the various nav & com antennas on my RV6 and decided to
>>> do a continuity check on them before connecting the cables. On the
>>> Aeroelectric transponder antenna, at the connector, the inner pin is
>>> insulated from the outer, and the inner has continuity with the shaft,
>>> all as I would expect.
>>>
>>>On my Comant VOR/LOC/GS cat wiskers, the ohm meter says the inner pin
>>> and outer connector are hooked together somewhere inside and have
>>> complete continuity, but the two "whiskers" are insulated from
>>> everything.
>>>
>>>The Comant marker beacon antenna also has continuity between the inner
>>> pin and the outer connector shell, but the actual antenna is buried
>>> inside the housing and I can't check that out.
>>>
>>>The bent whip Com antenna is different from the rest. The inner pin
>>> and outer shell are insulated from each other, but there is also no
>>> continuity between the inner pin and the whip.
>>>
>>>So, are the electronics correct, or do I have some defective antenna?
>>
>>
>> As a general rule, antennas cannot always be "tested" with an
>> ohmmeter. Some antennas may have matching networks consisting of
>> various inductors and capacitors that will make continuity
>> measurements confusing or meaningless. Active testing by exciting
>> the antenna with a source at the frequency of interest and
>> measuring resistive and reactive components (SWR) is the only
>> effective means for testing an antenna.
>>
>> As a general rule also, antennas are quite rugged. I cannot
>> recall ever having to replace an antenna that did not suffer some
>> catastrophic damage (collision, lighting stroke, etc).
>> So if your coax feedlines check out, go ahead and stick everything
>> together. If you find performance lacking after every thing is
>> installed, it is MORE likely that you have a problem with a radio
>> but it's easy to test the antenna as installed with test equipment
>> that will be in the possession of every decent avionics shop.
>>
>> Bob . . .
>>
Message 22
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| Subject: | Re: Antenna Electronics |
--> AeroElectric-List message posted by: "Cy Galley" <cgalley@qcbc.org>
Radio waves are AC and you are measuring DC resistance.
----- Original Message -----
From: "David Lundquist" <lundquist@ieee.org>
Subject: Re: AeroElectric-List: Antenna Electronics
> --> AeroElectric-List message posted by: "David Lundquist"
<lundquist@ieee.org>
>
> It is entirely possible that a perfectly good antenna can be either open
or
> a dead short when checked with an ohm meter. The ohm meter is only useful
> if you know what the antenna is supposed to be.
>
> Dave Lundquist
> lundquist@ieee.org
>
> ----- Original Message -----
> From: "John Rourke" <jrourke@allied-computer.com>
> To: <aeroelectric-list@matronics.com>
> Subject: Re: AeroElectric-List: Antenna Electronics
>
>
> > --> AeroElectric-List message posted by: John Rourke
> <jrourke@allied-computer.com>
> >
> > I would agree that an "open circuit" as shown with an ohmmeter is
> > entirely possible in a properly functioning antenna, but if it shows a
> > dead short of 0 ohms from the shielding to the center conductor, I can't
> > think of any way that antenna could function properly.
> >
> > If that is the case, I wouldn't want to initiate any transmission test
> > until the short is found - although I guess today's transceivers can
> > handle that, it still just doesn't sound like a good idea to me. Am I
> wrong?
> >
> > -John R.
> >
> > P.S.: Other than an RF power/SWR meter, what test equipment ought we to
> > have to run such tests?
> >
> >
> > Robert L. Nuckolls, III wrote:
> > > --> AeroElectric-List message posted by: "Robert L. Nuckolls, III"
> <bob.nuckolls@cox.net>
> > >
> > > At 09:37 PM 1/4/2003 -0500, you wrote:
> > >
> > >>--> AeroElectric-List message posted by: "Duane Bentley"
> <dbentley@fuse.net>
> > >>
> > >>Maybe I have some new, defective antennas or I don't understand the
> > >>electronics. I've read Bob's chapter on antenna theory, but don't
> readily
> > >>see the answer to my questions.
> > >>
> > >>I'm installing the various nav & com antennas on my RV6 and decided to
> do a
> > >>continuity check on them before connecting the cables. On the
> Aeroelectric
> > >>transponder antenna, at the connector, the inner pin is insulated from
> the
> > >>outer, and the inner has continuity with the shaft, all as I would
> expect.
> > >>
> > >>On my Comant VOR/LOC/GS cat wiskers, the ohm meter says the inner pin
> and
> > >>outer connector are hooked together somewhere inside and have complete
> > >>continuity, but the two "whiskers" are insulated from everything.
> > >>
> > >>The Comant marker beacon antenna also has continuity between the inner
> pin
> > >>and the outer connector shell, but the actual antenna is buried inside
> the
> > >>housing and I can't check that out.
> > >>
> > >>The bent whip Com antenna is different from the rest. The inner pin
and
> > >>outer shell are insulated from each other, but there is also no
> continuity
> > >>between the inner pin and the whip.
> > >>
> > >>So, are the electronics correct, or do I have some defective antenna?
> > >
> > >
> > > As a general rule, antennas cannot always be "tested" with an
> ohmmeter.
> > > Some antennas may have matching networks consisting of various
> > > inductors and capacitors that will make continuity measurements
> > > confusing or meaningless. Active testing by exciting the antenna
> > > with a source at the frequency of interest and measuring resistive
> > > and reactive components (SWR) is the only effective means for
> > > testing an antenna.
> > >
> > > As a general rule also, antennas are quite rugged. I cannot
> > > recall ever having to replace an antenna that did not suffer
> > > some catastrophic damage (collision, lighting stroke, etc).
> > > So if your coax feedlines check out, go ahead and stick everything
> > > together. If you find performance lacking after every thing is
> installed,
> > > it is MORE likely that you have a problem with a radio but it's
> > > easy to test the antenna as installed with test equipment that
> > > will be in the possession of every decent avionics shop.
> > >
> > > Bob . . .
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> >
> >
>
>
Message 23
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| Subject: | Re: Avionics Masters |
--> AeroElectric-List message posted by: "Cy Galley" <cgalley@qcbc.org>
What a great site for old radios. Brought back many old memories of my
expensive 1948 Buick with the dual point vibrator. Never could get the hash
out!
Cy Galley, TC - Chair, Emergency Aircraft Repair, Oshkosh
Editor, EAA Safety Programs
cgalley@qcbc.org or experimenter@eaa.org
Always looking for articles for the Experimenter
----- Original Message -----
From: "Robert L. Nuckolls, III" <bob.nuckolls@cox.net>
Subject: Re: AeroElectric-List: Avionics Masters
> --> AeroElectric-List message posted by: "Robert L. Nuckolls, III"
<bob.nuckolls@cox.net>
>
> At 11:54 AM 1/7/2003 -0700, you wrote:
> >--> AeroElectric-List message posted by: Walter Casey
<mikec@caseyspm.com>
> >
> >
> >Does anyone remember vacuum tube radios in automobiles. The vacuum
> >tubes required high voltage (over 90V) and to get this voltage the 6V
> >DC had to be converted to AC an run through a transformer. The DC to AC
> >converted was called vibrator and worked like an electric door bell.
> >When you turned on the radio the first thing you heard was the hum of
> >the vibrator. The vibrator was quite prone to failure due to contacts
> >sticking. As I understood it, it was to prevent the contact sticking
> >that the starter button was removed and replaced by the key
> >switch/starter which prevented the radio from being on while the car
> >was started.
> >
> >Old habits die hard.
>
> My first mobile rig was vibrator power supply powered. Had
> it installed in a 6-volt, 1941 Pontiac. Here's some more
> info on this bit of ancient but elegant technology at
> http://www.geocities.com/vintage_radio/vpwrsup.htm
>
> Bob . . .
>
>
Message 24
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|
| Subject: | Antenna Electronics |
--> AeroElectric-List message posted by: "Rod Kimmell" <rod.kimmell@worldnet.att.net>
What looks like a dead short or open to DC current flow on an antenna
will look entirely differerent to RF energy whether received or
transmitted.
Impedance is the AC equivalent of DC resistance and is a combination of
resistance, reactance, and frequency. Depending on the antenna design,
the DC measurement could be anythings for 0 to infinity. Most VHF/UHF
radios, including aircraft, typically expect to see a 50 ohm impedance
at the operating frequency. Some antennas have capacitance coupling
which would look like an open. Ever wonder how those glass mounted
cellular antennas work? Capacitive coupling through the glass.
For those interested, any Amateur Radio Relay League Handbook will have
more information.
Rod
-----Original Message-----
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Cy
Galley
Subject: Re: AeroElectric-List: Antenna Electronics
--> AeroElectric-List message posted by: "Cy Galley" <cgalley@qcbc.org>
Radio waves are AC and you are measuring DC resistance.
----- Original Message -----
From: "David Lundquist" <lundquist@ieee.org>
Subject: Re: AeroElectric-List: Antenna Electronics
> --> AeroElectric-List message posted by: "David Lundquist"
<lundquist@ieee.org>
>
> It is entirely possible that a perfectly good antenna can be either
> open
or
> a dead short when checked with an ohm meter. The ohm meter is only
> useful if you know what the antenna is supposed to be.
>
> Dave Lundquist
> lundquist@ieee.org
>
> ----- Original Message -----
> From: "John Rourke" <jrourke@allied-computer.com>
> To: <aeroelectric-list@matronics.com>
> Subject: Re: AeroElectric-List: Antenna Electronics
>
>
> > --> AeroElectric-List message posted by: John Rourke
> <jrourke@allied-computer.com>
> >
> > I would agree that an "open circuit" as shown with an ohmmeter is
> > entirely possible in a properly functioning antenna, but if it shows
> > a dead short of 0 ohms from the shielding to the center conductor, I
> > can't think of any way that antenna could function properly.
> >
> > If that is the case, I wouldn't want to initiate any transmission
> > test until the short is found - although I guess today's
> > transceivers can handle that, it still just doesn't sound like a
> > good idea to me. Am I
> wrong?
> >
> > -John R.
> >
> > P.S.: Other than an RF power/SWR meter, what test equipment ought we
> > to have to run such tests?
> >
> >
> > Robert L. Nuckolls, III wrote:
> > > --> AeroElectric-List message posted by: "Robert L. Nuckolls, III"
> <bob.nuckolls@cox.net>
> > >
> > > At 09:37 PM 1/4/2003 -0500, you wrote:
> > >
> > >>--> AeroElectric-List message posted by: "Duane Bentley"
> <dbentley@fuse.net>
> > >>
> > >>Maybe I have some new, defective antennas or I don't understand
> > >>the electronics. I've read Bob's chapter on antenna theory, but
> > >>don't
> readily
> > >>see the answer to my questions.
> > >>
> > >>I'm installing the various nav & com antennas on my RV6 and
> > >>decided to
> do a
> > >>continuity check on them before connecting the cables. On the
> Aeroelectric
> > >>transponder antenna, at the connector, the inner pin is insulated
> > >>from
> the
> > >>outer, and the inner has continuity with the shaft, all as I
> > >>would
> expect.
> > >>
> > >>On my Comant VOR/LOC/GS cat wiskers, the ohm meter says the inner
> > >>pin
> and
> > >>outer connector are hooked together somewhere inside and have
> > >>complete continuity, but the two "whiskers" are insulated from
> > >>everything.
> > >>
> > >>The Comant marker beacon antenna also has continuity between the
> > >>inner
> pin
> > >>and the outer connector shell, but the actual antenna is buried
> > >>inside
> the
> > >>housing and I can't check that out.
> > >>
> > >>The bent whip Com antenna is different from the rest. The inner
> > >>pin
and
> > >>outer shell are insulated from each other, but there is also no
> continuity
> > >>between the inner pin and the whip.
> > >>
> > >>So, are the electronics correct, or do I have some defective
> > >>antenna?
> > >
> > >
> > > As a general rule, antennas cannot always be "tested" with an
> ohmmeter.
> > > Some antennas may have matching networks consisting of various
> > > inductors and capacitors that will make continuity
measurements
> > > confusing or meaningless. Active testing by exciting the
antenna
> > > with a source at the frequency of interest and measuring
resistive
> > > and reactive components (SWR) is the only effective means for
> > > testing an antenna.
> > >
> > > As a general rule also, antennas are quite rugged. I cannot
> > > recall ever having to replace an antenna that did not suffer
> > > some catastrophic damage (collision, lighting stroke, etc).
> > > So if your coax feedlines check out, go ahead and stick
everything
> > > together. If you find performance lacking after every thing is
> installed,
> > > it is MORE likely that you have a problem with a radio but
it's
> > > easy to test the antenna as installed with test equipment that
> > > will be in the possession of every decent avionics shop.
> > >
> > > Bob . . .
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> >
> >
>
>
direct advertising on the Matronics Forums.
Message 25
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| Subject: | Re: Radio Master Switch |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <bob.nuckolls@cox.net>
At 10:40 AM 1/7/2003 +0100, you wrote:
>--> AeroElectric-List message posted by: "Werner Schneider"
><WernerSchneider@compuserve.com>
>
> >
> > Yup . . . I've seen it, and others like it for
> > years. I can't remember if I wrote to this particular
> > author or not. I used to attempt contact with everyone who
> > published articles touting the virtues of an avionics
> > master with respect to protecting radios from airplane
> > gremlins. My question has always been, "Please identify
> > for me the source, duration and magnitude of any
> > transient that might endanger the health and well-being
> > of any piece of electronics.
> >
>.
> >
> > Bob . . .
> >
>Just started installing my "things" and I have a used Insight engine monitor
>GEM 602 in the installation instructions (Version 3.0 May 1996) Page 6
>
>
>.....If the aircraft installation does not include an Avionics Master switch
>circuit or bus, we recommend that one be installed or a separate switch
>provided to remove power from the Display during engine starts.
>
>Should I really follow the separate switch way (tube display) or just ignore
>(Bob, do you want the notes in pdf form for asking them =(;o))
What does Insight say are the consequences of not
waiting until after the engine is started to turn on
their system? I suspect they've not done their homework
on a microcontroller and the thing wanders off into the
weeds during brownout. If this is the case, and you
want to use the product, put the system on it's own
power switch and write a procedure into your manual for
keeping it OFF until after the engine is started.
Had a builder some years ago find that the display
processor on one of his instruments locked up during
brownout. He just added a normally closed pushbutton
next to the instrument that was in series with the
+14V power. After startup, he would hold the button
in for a second to interrupt the power and cause the
processor to do a normal re-set.
Some people put such products on the market thinking
they can hide their shortcomings behind somebody else's
avionics master switch. The normally closed push-button
might be an option for you too . . . you can label
Push for WAKE UP
Bob . . .
Message 26
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| Subject: | Good price on battery tester |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <bob.nuckolls@cox.net>
Check out the specials/consignment section of
http://www.aeroelectric.com/Catalog/AECcatalog.html
Bob . . .
|-------------------------------------------------------|
| The man who does not read good books has no advantage |
| over the man who cannot read them. |
| - Mark Twain |
|-------------------------------------------------------|
Message 27
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| Subject: | Re: Good price on battery tester |
--> AeroElectric-List message posted by: BobsV35B@aol.com
In a message dated 1/7/03 3:14:04 PM Central Standard Time,
bob.nuckolls@cox.net writes:
> Check out the specials/consignment section of
>
> http://www.aeroelectric.com/Catalog/AECcatalog.html
>
> Bob . . .
>
Good Afternoon Bob,
The battery tester sounds interesting. Is there anything similar available
for twenty-four volt batteries?
Happy Skies,
Old Bob
Message 28
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--> AeroElectric-List message posted by: "John Slade" <sladerj@bellsouth.net>
Bob,
My dimmer unit (DIM15-14 - came with the gooseneck light) seems to have
died. It gets hot, but doesnt light the lights. I had this problem a few
weeks ago, but it came back on. Last week I connected one of the dimmer
output's to the LEDs which light up my fuel sight guages. It worked fine,
but now it's acting up again.
Any suggestions?
John Slade
Cozy IV #757
Message 29
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| Subject: | Re: Dead Dimmer? |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <bob.nuckolls@cox.net>
At 04:52 PM 1/7/2003 -0500, you wrote:
>--> AeroElectric-List message posted by: "John Slade" <sladerj@bellsouth.net>
>
>Bob,
>My dimmer unit (DIM15-14 - came with the gooseneck light) seems to have
>died. It gets hot, but doesnt light the lights. I had this problem a few
>weeks ago, but it came back on. Last week I connected one of the dimmer
>output's to the LEDs which light up my fuel sight guages. It worked fine,
>but now it's acting up again.
>Any suggestions?
>John Slade
>Cozy IV #757
If the dimmer is getting hot but the light doesn't light
up, then there is most likely a short circuit that is
causing the dimmer to go into thermal shutdown. The short
would have to be in wiring between the dimmer and the
lamp fixture or in the fixture itself.
Bob . . .
Message 30
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| Subject: | Re: Good price on battery tester |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <bob.nuckolls@cox.net>
At 04:40 PM 1/7/2003 -0500, you wrote:
>--> AeroElectric-List message posted by: BobsV35B@aol.com
>
>In a message dated 1/7/03 3:14:04 PM Central Standard Time,
>bob.nuckolls@cox.net writes:
>
> > Check out the specials/consignment section of
> >
> > http://www.aeroelectric.com/Catalog/AECcatalog.html
> >
> > Bob . . .
> >
>
>Good Afternoon Bob,
>
>The battery tester sounds interesting. Is there anything similar available
>for twenty-four volt batteries?
>
>Happy Skies,
>
>Old Bob
Somebody probably makes one for commercial aviation and military
applications but you can bet it wouldn't be a $240 device. I'm
not aware of any specific products I can guide you toward . . .
Bob . . .
Message 31
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| Subject: | Re: Avionics Masters |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <bob.nuckolls@cox.net>
At 07:42 AM 1/7/2003 -0800, you wrote:
>--> AeroElectric-List message posted by: "Gary Casey" <glcasey@adelphia.net>
>
><<I was at Cessna when the avionics master was born, and
> we thought we had a good reason . . . . over the years
> the reasoning, experience and technology upon which
> the decision was made are long since gone the way of
> the buggy whip.
>
> Bob . . . >>
>
>Just as a point of reference, my Cardinal apparently was equipped with an
>"avionics master relay" which was a normally closed relay between the main
>buss and the avionics buss. The coil was connected to the starter terminal
>on the ignition switch so that when the starter was engaged the avionics
>were turned off. It either only showed up in the service manual, never
>being installed, or had been removed at some point in its life. Another
>single point of failure.
>
>As far as I can tell there are very minor voltage transients that occur
>during cranking. The first is when the starter is engaged and the battery
>voltage takes a virtually instantaneous drop to some lower voltage. During
>cranking the battery voltage will smoothly rise and fall with each
>compression stroke, accompanied by a ripple voltage from starter commutator
>segments. When the starter is released the voltage will step back to a
>no-load condition, not overshooting. The inductive surge from the starter
>exists on the STARTER side of the contactor and doesn't exist at the main
>buss. Car systems shut off some of the electronics during cranking because
>they only need to shut off the heater blower and the electronics were just
>hooked to the same switch terminal because it was there.
>
>It would be tempting, I suppose, to hook the starter contactor directly to
>the battery and leave the master off during cranking. But then there would
>be no way to disconnect the starter if the contactor welded.
>
>Gary Casey
I've had data acquisition systems tied to perhaps 30 different
airplanes over the years to look for voltage aberrations. Early
explorations were with relatively slow chart recorders. Later
measurements used 8000 sample/second data acquisition adapters
on a computer. I've never been able to catch a killer starting
transient in the wild . . . During contactor bounce, there
are some short fuzzy spikes of very low energy content when
measured at the bus. If there are any capacitors on the input
circuits to powered devices, these little fellers disappear
completely. the next most noted artifact is battery voltage
at starter inrush current levels that typically pulls the
battery down to 6 volts or so for about 2 milliseconds. It
rises quickly as the motor begins to turn an passes 8 volts
in about 10 milliseconds. After the engine starts and
the starter is released, there are no significant
transients when the contactor opens.
Some folks call the inrush artifact a "spike" and indeed
on the oscilloscope, it's pretty pointy . . . but it's
relatively long compared to the kinds of real spikes
that used to trip our ov modules by a factor of 50 or
more. Further, the negative going excursion stays inside
the range of voltages any device should expect
to see in normal operations . . . zero to 15 volts.
I prefer to call it a perfectly acceptable and
expected effect of hitting the battery with a 1000A
inrush transient and as such should not be a threat
to ANY other part of the airplane. DO-160 says so
too . . .
Bob . . .
Message 32
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| Subject: | Re: Dead Dimmer? |
--> AeroElectric-List message posted by: John Schroeder <jschroeder@perigee.net>
Bob . . .
John Slade mentioned that he can run LED's with the dimmer on your gooseneck
lamp.
Does the lamp have a LED or LED's?
Can you run more than one light off of the dimmer?
Thanks,
John Schroeder
>>My dimmer unit (DIM15-14 - came with the gooseneck light) seems to have
>>died. It gets hot, but doesnt light the lights. I had this problem a few
>>weeks ago, but it came back on. Last week I connected one of the dimmer
>>output's to the LEDs which light up my fuel sight guages. It worked fine,
>>but now it's acting up again.
> If the dimmer is getting hot but the light doesn't light
> ... .>
> Bob . . .
>
>
Message 33
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|
| Subject: | CESSNA Cardinal NO AVIONICS MASTER |
--> AeroElectric-List message posted by: Don Boardman <dboardm3@twcny.rr.com>
Hi all,
Funny thing, if Cessna put an avionics master in 100,000 airplanes they must
have missed my 1971 Cardinal RG ... or maybe this model was supposed to be
ahead of it's time?
Starting to wire my Murphy Moose soon and I think I will follow Cessna's
lead and leave out the avionics master!
Bob, I may be bugging you in the near future with some questions as I
proceed with my dual alt and single bat system.
Thanks for all the generosity you apply to this list,
Regards,
Don Boardman & Partner, Randy Bowers
Murphy Moose #130 M-14PF 400HP, MT-prop, Aerocet 3500 amphibs, Rome, NY
Message 34
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--> AeroElectric-List message posted by: "John Slade" <sladerj@bellsouth.net>
> Does the lamp have a LED or LED's?
No. Its a very low wattage bulb.
> Can you run more than one light off of the dimmer?
Bob may give you a more complete answer but yes, you can run any number of
LED's off the dimmer. It has five outputs. I use one for the fuel gauges,
one for the transponder / radio lights, one for the panel lights and one for
the goose neck light. I still have a spare output. My only complaint, other
than the fact that it aint working right now, is that it doesnt dim down far
enough.
Off to check my wiring.
John Slade
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