Today's Message Index:
----------------------
1. 05:22 AM - Re: P-mag Internal Power Test (Andrew Butler)
2. 06:25 AM - Flightcom headset (luigit@freemail.it)
3. 06:25 AM - Re: Kitplanes article on solar power (Joe)
4. 07:15 AM - Re: P-mag Internal Power Test (Robert L. Nuckolls, III)
5. 07:22 AM - Dual Battery Dual Alternator Grounding (dsyvert)
6. 07:26 AM - Re: Re: Fixed connector on the Transponder Mounting Tray (Robert L. Nuckolls, III)
7. 07:29 AM - Re: Flightcom headset (Robert L. Nuckolls, III)
8. 08:33 AM - Re: Dual Battery Dual Alternator Grounding (Robert L. Nuckolls, III)
9. 10:53 AM - Re: Bus Voltage (Speedy11@aol.com)
10. 01:09 PM - Re: Van's gauges (Robert L. Nuckolls, III)
11. 01:37 PM - Re: Re: Filter for Hand held devices (Robert L. Nuckolls, III)
12. 02:22 PM - Re: Re: Filter for Hand held devices (Ian)
13. 03:45 PM - Re: Van's gauges (John Danielson)
14. 07:21 PM - Aerobatics and Instrument Damage (PeterHunt1@aol.com)
15. 08:19 PM - Re: Aerobatics and Instrument Damage (BobsV35B@aol.com)
16. 09:32 PM - Re: Re: Filter for Hand held devices (Robert L. Nuckolls, III)
17. 10:17 PM - Transmit problem on both comm radios. (DEAN PSIROPOULOS)
18. 11:16 PM - Re: Re: Filter for Hand held devices (Jay Hyde)
Message 1
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Subject: | Re: P-mag Internal Power Test |
Hi Mike,
Here is some additional info. I got from Emagair directly last year when researching
the units. I personally have wired up according to Z13, with two switches
for each unit, p-lead and power. I don't have CBs for the circuits, rather fuses.
Regards, Andrew.
-------------------------------------------------------------------------------------------------------------------
From: info@emagair.com [mailto:info@emagair.com]
Sent: 09 May 2008 16:57
Subject: RE: Startup Checks
Andrew:
When an ignition is first powered up it has to wake up, load the operating code,
track engine position, determine when the next spark even needs to happen, and
finally trigger that spark event. If you power up while the engine is running
all this has to happen very quickly. Since P models make their own power
(as long as the engine is running), you cannot shut down the processor. You
can turn both the p-lead and the 12 supply OFF and it will still be "awake" doing
its business as usual, waiting to resume firing as soon as the p-lead is ungrounded.
With E models, however, you can power them OFF when running, and the
ignition (truly) will go dark - still no problem. Powering the E model OFF
is not the issue. It's when you 1) power an E model ON (while the engine is
running) and 2) with the p-lead ungrounded that you are asking it to instantaneously
wake up and start firing as described above. The condition can be avoided
(if encountered) by making sure the p-lead is grounded (OFF) before powering
(12 volt) ON an E model ignition while the engine is running.
Even so, if this happens, we aren't predicting disaster. It will probably resume
operation just fine, but there is no reason to do it in the first place - that's
all.
I don't recall any customers (yet) in Ireland - congratulations, you'll be number
1.
Kindest Regards,
Brad Dement
E-MAG Ignitions
2014 Greg Street Box 112
Azle, Texas 76020
(817) 444-5310
From: Butler, Andrew [mailto:andrew.butler@nuigalway.ie]
Sent: Friday, May 09, 2008 10:29 AM
Subject: RE: Startup Checks
Thanks very much Brad.
What is the logic behind not switching off power to an E-MAG while the
engine is running? I am assuming that switching off power is okay, that it is
switching power back on while the engine is turning that is the problem. What
exactly is the event sequence associated with switching on power while the engine
is turning that is problematic?
Why is it problematic to turn power on while the P-MAG is live i.e ungrounded?
I am not installing a rotary key switch, rather an individual power switch for
each ignition. It appears that I will need a two position switch that allows me
to control access to power and ground individually.
Cheers, Andrew.
RV71700
Galway, Ireland.
From: info@emagair.com [mailto:info@emagair.com]
Sent: 08 May 2008 17:07
Subject: RE: Startup Checks
Hi Andrew:
Thanks for considering us for your project.
The ignition check for E-MAG ignitions is very similar to that of magnetos. You'll
do your regular L/R (p-lead) check to make sure both ignitions operate.
The only difference is that for each P model ignition you have installed (one
or both) you'll add one additional sequence. While switched to the individual
P model(s), simply turn OFF the 12 volt power that feeds that ignition for a
few seconds to verify the engine continues to run. If the engine runs, the internal
alternator is operating. If the engine quits, the alternator is not working.
The engine speed should be 1000 rpm or greater when you do this check.
There is no need to do this test with an E model as they don't have an alternator.
The L/R test is a p-lead (ON/OFF) test applicable to both E and P models.
The 12 power (ON/OFF) test is applicable to P models only, and we discourage
doing it with E models, so the FAQ you refer to is not in conflict with the pre-flight
ignition tests.
The Installation and Operating Guide also has some recommendations on starting
with our equipment - see Downloads page on our web site.
Don't hesitate to call or drop us a note if you have any other questions.
Kindest Regards,
Brad Dement
E-MAG Ignitions
2014 Greg Street Box 112
Azle, Texas 76020
(817) 444-5310
-------------------------------------------------------------------------------------------------------
----- Original Message -----
From: "Robert L. Nuckolls, III" <nuckolls.bob@aeroelectric.com>
Sent: Monday, 21 September, 2009 2:11:36 AM GMT +00:00 GMT Britain, Ireland, Portugal
Subject: Re: AeroElectric-List: P-mag Internal Power Test
At 03:45 PM 9/20/2009, you wrote:
>
>I am getting my wiring started and have a question on how some of
>you with P-Mags wired your systems. There are two tests for th
>P-Mag as I understand things. One is just like a traditional
>magneto check, you turn off (ground the p-lead) and check for mag
>drop. The other check for a P-Mag is to turn off the 12v power to
>the P-Mag to check that the internal alternator keeps the magneto
>running. The check of the internal alternator does not seem like
>something that needs to be check each flight. I am considering just
>pulling the CB for each P-Mag to make this check rather than wiring
>a switch to serve this purpose.
>
>What have others done with regard to this, I don't want to use a
>switched breaker, I will just add the switch if it is required. My
>thinking is to just pull the breaker. We pull breaker on the B-767
>at the end of each flight to turn some equipment off while the plane
>sits between flights, so I don't think there is an issue of waring
>out a breaker. Thanks for any pointers.
What you've proposed is consistent with Emagair's
recommendations. In fact, Figure Z13/8 was crafted
with a similar philosophy.
http://www.aeroelectric.com/PPS/Adobe_Architecture_Pdfs/Z13-8Q.pdf
Note that with ship's power taken through
a fuse from the main bus, the internal power
source integrity can be verified occasionally
by checking engine operations on the p-mag while
the main bus is down. Easy to do under comfortable
conditions and only occasionally.
Bob . . .
---------------------------------------
( . . . a long habit of not thinking )
( a thing wrong, gives it a superficial )
( appearance of being right . . . )
( )
( -Thomas Paine 1776- )
---------------------------------------
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Subject: | Flightcom headset |
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Message 3
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Subject: | Re: Kitplanes article on solar power |
Carlos,
Try this link: http://www.kitplanes.com/issues/pdfs/0107-6566.pdf
Jim Weir's website: http://www.rst-engr.com/rst/contact_us.html
I will send an email to you with a scanned copy of the schematic.
Joe
Michigan USA
Message 4
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Subject: | Re: P-mag Internal Power Test |
At 06:47 AM 9/21/2009, you wrote:
><andrewbutler@ireland.com>
>
>Hi Mike,
>
>Here is some additional info. I got from Emagair directly last year
>when researching the units. I personally have wired up according to
>Z13, with two switches for each unit, p-lead and power. I don't have
>CBs for the circuits, rather fuses.
>
>Regards, Andrew.
<snip>
Thanks for that expansion Andrew. I had a similar
dissertation from the guys at Emagair but couldn't
lay my hands on it last night.
Bob . . .
---------------------------------------
( . . . a long habit of not thinking )
( a thing wrong, gives it a superficial )
( appearance of being right . . . )
( )
( -Thomas Paine 1776- )
---------------------------------------
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Subject: | Dual Battery Dual Alternator Grounding |
I have two #2 AWG cables running from the back of my RV-10 to the firewall. My
question is if I put in two batteries and two alternators, where do I ground each
one. Van's plans show the grounding at the behind the baggage bulk head. Could
both batteries be grounded there to a common ground? I intended to use the
second cable as a ground from the battery to the firewall, but Van's shows it
to be grounded to the battery box.
Sorry if this has already been addressed
dsyvert
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=264118#264118
Message 6
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Subject: | Re: Fixed connector on the Transponder Mounting |
Tray
>How does a BNC connector hook up with these connectors, like the end
>on a TED aerial???
>
These connectors accept a prepared end of the antenna's
feed-line coax. They are solder joints for both the
center conductor and shield.
If you want to break that feedline with a connector
adjacent to the radio, then the segment that comes
off the slip-connector is simply shortened to a pigtail
of the desired length which is then terminated in a
cable-female . . .
http://www.aeroelectric.com/Pictures/Connectors/Coax/BNC_Cable_Female_2.jpg
Bob . . .
---------------------------------------
( . . . a long habit of not thinking )
( a thing wrong, gives it a superficial )
( appearance of being right . . . )
( )
( -Thomas Paine 1776- )
---------------------------------------
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Subject: | Re: Flightcom headset |
At 07:58 AM 9/21/2009, you wrote:
>
><snip>
>
>Not usual for me this kind of assistance.
>
>Thank you Becky and thank you Flightcom.
>
>A very good headset and an excellent service.
>
>Luigi
Your observations agree with my own. The few times
I've had occasion to communicate with Flightcom,
their willingness to share has been exemplary . . .
and I'm not even a customer!
Bob . . .
---------------------------------------
( . . . a long habit of not thinking )
( a thing wrong, gives it a superficial )
( appearance of being right . . . )
( )
( -Thomas Paine 1776- )
---------------------------------------
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Subject: | Re: Dual Battery Dual Alternator Grounding |
At 09:20 AM 9/21/2009, you wrote:
>
>I have two #2 AWG cables running from the back of my RV-10 to the
>firewall. My question is if I put in two batteries and two
>alternators, where do I ground each one. Van's plans show the
>grounding at the behind the baggage bulk head. Could both batteries
>be grounded there to a common ground? I intended to use the second
>cable as a ground from the battery to the firewall, but Van's shows
>it to be grounded to the battery box.
Independent grounds to structure will be
consistent with design goals for elimination
of single points of failure. See . . .
http://aeroelectric.com/Pictures/Batteries/Battery_Install_OBrien_2.jpg
do this for EACH battery. Also, 4AWG welding cable
jumpers from battery(+) to contactor and battery(-)
to ground are a good idea to minimize mechanical
stress on terminals.
Bob . . .
---------------------------------------
( . . . a long habit of not thinking )
( a thing wrong, gives it a superficial )
( appearance of being right . . . )
( )
( -Thomas Paine 1776- )
---------------------------------------
Message 9
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Joe,
I took careful notice of the bus voltage yesterday as I loaded up the bus
and you've brought up a good point. At an 8 amp load, the bus voltage was
13.5. At 29 amps it dropped to 13.2 and stayed there until I reduced the
load. So, I must have too small a wire from the alternator to the bus.
I'll consider changing it.
Thanks,
Stan Sutterfield
Joe,
Thanks for your comment.
I have taken notice of the voltage during light and heaviest loads and it
remains steady at 13.5. The light loading was about 3 Amps and heavy was
about 32A (everything on).
So, I'll take readings as Bob suggested and see what I find.
Stan
Stan,
A good test is to compare the bus voltage with light loads to the bus
voltage with heavy loads. If there is a big difference, then there is a
lot of resistance in the circuit, possibly from too small wire or from
bad connections.
Joe
Message 10
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Subject: | Re: Van's gauges |
At 12:46 PM 9/14/2009, you wrote:
>In 420 house over three plus years a number of Van's gauges have
>failed (fuel quantity, volts, amps, oil pressure). Now I must
>install the third volt meter. I like the look of Van's gauges and
>the fact that they match, but don't like the failure rate. What
>have your experiences been?
>
>Pete in Clearwater
>RV-6 - Reserve Grand Champion, S 'n F 2006 and other awards
>
>----------
Peter,
Sorry to hear about this . . . I've got a Van's ammeter
on the bench which I disassembled to look at. Hand-
assembled, thru-hole components (not necessarily
a 'bad' thing, especially in TC aviation!). However,
the ammeter proved to be exceptionally vulnerable
to radio-frequency fields (hand held).
It's a line-item on my things-to-do list to see what
sort of filter/shielding would reduce the effects to
acceptable levels.
My discovery raises a perplexing question . . .
How much of the technology and design goals for
the ammeter are common to the rest of the product
line? Of course, my question only goes to system
integration . . . a question which is moot if the
critters have an unacceptable failure rate.
Your question is the first I've heard of it. I'd
be pleased to have updates from the rest of List
membership.
P.S. Sorry we didn't get together while attending
to Dr. Dee at the convention last winter. It was
an interesting and opportunity-packed event. I don't
think we got out of the hotel more than a half dozen
trips to local eateries!
Bob . . .
---------------------------------------
( . . . a long habit of not thinking )
( a thing wrong, gives it a superficial )
( appearance of being right . . . )
( )
( -Thomas Paine 1776- )
---------------------------------------
Message 11
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Subject: | Re: Filter for Hand held devices |
At 08:11 AM 9/14/2009, you wrote:
>
>I think that I do need one; I am using a cigarette lighter type connection
>to power an Ipod power supply. When I connect this to the Ipod no noise is
>heard, but when I connect the Ipod to the radio/ intercom system I
>immediately get a high pitched noise in the earphones.
Okay, 'high pitched' is not alternator noise. It
MIGHT be an artifact of the dc/dc converter in your
ipod power adapter. Try first to power the Ipod internally
without the adapter. Does the noise go away? Try powering
the adapter fromits own 12 battery pack NOT connected to the a/c
in any way. A couple of el-cheeso 6v lantern batteries in
series a good diagnostic supply.
> I separated the
>power and signal leads and the noise stayed. I moved the power supply of
>the cigarette/ Ipod charger directly to the battery and the noise stayed. I
>will still try a twisted pair on the power supply to the radio/intercom but
>it seems to me that the noise is generated by the Ipod charger so I thought
>that a filter might do the trick. Perhaps even a ferrite bead on the
>positive in to the radio will work.
>
>The only other thing that I can think of is that the loop formed by the
>plug->Ipod charger->Ipod audio out->radio/intercom is somehow causing the
>problem; but how does one get rid of that loop- its intrinsic to the music
>input?
It's most likely to be a ground loop issue which will be
re-enforced or denied by the above experiments.
In any case, it's almost a certainty that filtering
is not solution for root cause.
We may have to incorporate an isolation transformer
where audio from your Ipod goes to one winding and
audio to the ship's system is taken from the other
winding. See:
http://www.radioshack.com/product/index.jsp?productId=2103994
Bob . . .
Message 12
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Subject: | Re: Filter for Hand held devices |
Just for information of those on the list, I recently had a faulty 12V
charger on an AV8OR. The manufacturer willingly changed it. The
symptoms were more your conventional white noise type static, like a
very weak radio signal - there when charging the AV8OR, gone when not.
It interfered with radio reception in the car and in the aircraft. I'm
not proposing it as the cause of the IPOD problem below, just a useful
data point. Faulty chargers do indeed seem capable of generating
interference but not, in my case, a high pitched noise.
Ian Brown
Bromont, Quebec
> >The only other thing that I can think of is that the loop formed by the
> >plug->Ipod charger->Ipod audio out->radio/intercom is somehow causing the
> >problem; but how does one get rid of that loop- its intrinsic to the music
> >input?
>
> It's most likely to be a ground loop issue which will be
> re-enforced or denied by the above experiments.
>
> In any case, it's almost a certainty that filtering
> is not solution for root cause.
>
> We may have to incorporate an isolation transformer
> where audio from your Ipod goes to one winding and
> audio to the ship's system is taken from the other
> winding. See:
Message 13
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I also used Van's Gauges.
I had trouble with the ammeter also. Never did get it to work quite right.
It worked OK until you transmitted.
The oil pressure gauge only worked when the engine oil was cold. After the
temperature climbed to normal temps, the pressure would drop to 20 of 30 ps
i, sometimes to 0.
The rest of my Vans gauges (fuel quant, fuel pressure, tachometer, volt met
er, manifold pressure) worked great after 300 hrs.
John Danielson
________________________________
From: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectr
ic-list-server@matronics.com] On Behalf Of Robert L. Nuckolls, III
Sent: Monday, September 21, 2009 2:08 PM
Subject: Re: AeroElectric-List: Van's gauges
At 12:46 PM 9/14/2009, you wrote:
In 420 house over three plus years a number of Van's gauges have failed (fu
el quantity, volts, amps, oil pressure). Now I must install the third volt
meter. I like the look of Van's gauges and the fact that they match, but
don't like the failure rate. What have your experiences been?
Pete in Clearwater
RV-6 - Reserve Grand Champion, S 'n F 2006 and other awards
________________________________
Peter,
Sorry to hear about this . . . I've got a Van's ammeter
on the bench which I disassembled to look at. Hand-
assembled, thru-hole components (not necessarily
a 'bad' thing, especially in TC aviation!). However,
the ammeter proved to be exceptionally vulnerable
to radio-frequency fields (hand held).
It's a line-item on my things-to-do list to see what
sort of filter/shielding would reduce the effects to
acceptable levels.
My discovery raises a perplexing question . . .
How much of the technology and design goals for
the ammeter are common to the rest of the product
line? Of course, my question only goes to system
integration . . . a question which is moot if the
critters have an unacceptable failure rate.
Your question is the first I've heard of it. I'd
be pleased to have updates from the rest of List
membership.
P.S. Sorry we didn't get together while attending
to Dr. Dee at the convention last winter. It was
an interesting and opportunity-packed event. I don't
think we got out of the hotel more than a half dozen
trips to local eateries!
Bob . . .
---------------------------------------
( . . . a long habit of not thinking )
( a thing wrong, gives it a superficial )
( appearance of being right . . . )
( )
( -Thomas Paine 1776- )
---------------------------------------
Message 14
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Subject: | Aerobatics and Instrument Damage |
I have completed some excellent Unusual Attitude training in a Cap-10 which
included loops, rolls and spins and will soon complete additional aerobatic
training. Then I would like to try some of these aerobatics maneuvers in
my RV-6. However, I am a little concern that the gyro tumbling and/or G
forces of aerobatics may hurt my instruments. I have an AI, HSI and S-TEC
autopilot all containing electric gyros and would hate to damage them. What has
been your experience with aerobatics and instrument damage? Should I be
concerned about this?
Pete in Clearwater
RV-6, Day/night IFR, Reserve Grand Champion S 'n F
Message 15
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Subject: | Re: Aerobatics and Instrument Damage |
Good Evening Peter,
As Always, It All Depends! <G>
Your S-Tec uses the canted gyro in the Turn Coordinator for it's sensing
device. That gyro will not be harmed by aerobatics. The attitude and heading
gyros MAY be damaged! There are many different designs and your best bet is
to check with the manufacturer of your instrumentation. Some of the newer
instruments are suitable for aerobatic use. There were some fully aerobatic
artificial horizons built about fifty years ago, but the pitch indication
was just the opposite of what is standard today. There are a few older
gyros that allow the gyros to be caged, but that is not a real good idea. It
can keep the gyro from banging the stops, but the bearings will still incur
abnormal wear.
The best bet is to have a removable gyro panel to be used when not flying
aerobatics. A few of the professional aerobatic pilots have made such a set
up to save wear and tear during violent aerobatic flight.
One more comment if you don't mind.
The turn Coordinator (as is used by S-Tec for sensing) is an abominable
instrument in that it never tells the truth. For use during aerobatics, I much
prefer a standard old fashioned Turn needle combined with an inclinometer
Ball. The classic needle and ball. It is the most reliable directional
instrument you can buy and it can be used for spin recovery as well as
unusual attitude recovery. A turn coordinator can provide confusing and
counterproductive indications during a spin recovery. However, neither the T&B
nor
the TC will be damaged by doing such maneuvers.
Many of the modern glass panels use solid state "gyros" that are not
damaged by aerobatics, but some will lose proper sensing.
Any help at all?
Happy Skies,
Old Bob
AKA
Bob Siegfried
Downers Grove, Illinois
LL22
Stearman N3977A
In a message dated 9/21/2009 9:22:37 P.M. Central Daylight Time,
PeterHunt1@aol.com writes:
I have completed some excellent Unusual Attitude training in a Cap-10
which included loops, rolls and spins and will soon complete additional
aerobatic training. Then I would like to try some of these aerobatics maneuvers
in my RV-6. However, I am a little concern that the gyro tumbling and/or G
forces of aerobatics may hurt my instruments. I have an AI, HSI and S-TEC
autopilot all containing electric gyros and would hate to damage them.
What has been your experience with aerobatics and instrument damage? Should I
be concerned about this?
Pete in Clearwater
RV-6, Day/night IFR, Reserve Grand Champion S 'n F
(http://www.matronics.com/Navigator?AeroElectric-List)
(http://www.matronics.com/contribution)
Message 16
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Subject: | Re: Filter for Hand held devices |
At 04:18 PM 9/21/2009, you wrote:
>Just for information of those on the list, I recently had a faulty
>12V charger on an AV8OR. The manufacturer willingly changed
>it. The symptoms were more your conventional white noise type
>static, like a very weak radio signal - there when charging the
>AV8OR, gone when not. It interfered with radio reception in the
>car and in the aircraft. I'm not proposing it as the cause of the
>IPOD problem below, just a useful data point. Faulty chargers do
>indeed seem capable of generating interference but not, in my case,
>a high pitched noise.
The modern DC/DC converter technology has become smaller
and more efficient as the components became available to
operate at high and higher frequencies. The DC to DC
converters that we used in the Cessna Nav/Com 300 in 1965
ran at about 1 Khz . . . and had relatively benign
RF interference potential. That little nugget of electronics
that exists in the cigar lighter plug on your ipod or cell
phone charger probably operates at 1000 to 2000 times higher
frequency. These guys are much more likely to become
noise emitters in the AM radio band. I've had
several devices that I had to throw away and substitute
another brand.
Bob . . .
Bob . . .
---------------------------------------
( . . . a long habit of not thinking )
( a thing wrong, gives it a superficial )
( appearance of being right . . . )
( )
( -Thomas Paine 1776- )
---------------------------------------
Message 17
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Subject: | Transmit problem on both comm radios. |
Hi all:
Maybe you can help with my transmit problems. I have a UPS Aviation
Technologies (now Garmin AT) radio stack with SL-30 Nav Comm, GX-65
GPS/Comm, SL-70 transponder and SL-10MS audio panel (actually a PS-6000 with
UPS AT nameplate). I checked out everything according to the installation
manuals while the airplane was sitting on the ramp and the engine NOT
running. Now that I've been flying a lot, I'm getting a crackling in the
sidetone and when I look at the "TX" light on the radio it's flickering as
if someone were pulsing the press-to-talk switch 4-5 times per second, even
though I'm holding the PTT down tight. This happens on both radios and
people in the pattern say I'm breaking up and garbled. I've tried several
things looking for a solution, they are:
1) Turn down the MIC gains on both radios (in steps, a little at a time,
over several flights). In the end I had them turned down so much I couldn't
get a side tone in the earphones and suspect no-one could hear me at all.
2) I tried a couple different headsets (inexpensive non ANR types,
Sigtronics and Pilot Avionics units, both around 15 years old but well taken
care of and worked just fine in the Cessnas I used to rent). No joy.
3) I tried both headsets with and without foam muffs over the microphones.
No difference that I could tell with or without the muffs.
4) Placed ferrite beads over both coax lines running to the transmit
antennas (about 3/4 of the way down to the antennas, don't have access to
the base of the antennas right now, but will when I remove the floor panels
for annual inspection). No help!
5) Shut off the field in my B&C LR-60 alternator (with external regulator)
to operate on battery only. No change (I'm using forest of ground tabs ala
AEC philosophy and I'm NOT getting alternator noise in the reception of
either radio so I didn't expect this to help but it was easy to test).
6)Since I used fine (24 gauge 5 condutor MAC servo cable, no shielding) wire
to take the PTT signal from the PTT on the control stick to the pilots mic
jack, I thought maybe that was causing a problem so I tried using the
passengers PTT (wired with 22 ga shielded tefzel) instead of the pilots. No
change.
7) The audio panel has a built in fail-safe feature that routes the PTT and
mic/earphone signals direct to the number 1 NAV/COM in the event of audio
panel failure. I shut off the audio panel and tried that. The NAV/COMM TX
light comes on but still flickers and is crackly so it's not that. I of
course could not test the #2 radio this way but would expect it to be the
same.
Transmit antenna location is under the belly of the airplane (all metal
RV-6A). Two Comant bent whips about 40 inches apart just aft of the wing
spar.
The GPS portion of the GX-60 and VOR/ILS portion of the SL-30 work just
fine. Comm reception on both radios is loud and clear (at least I can hear
people in the pattern even if I can't talk to them).
When I originally ran through the installation checkout I left the settings
on the radios at the factory recommended (transmit worked fine so I left the
settings alone) and have been making changes to the Mic gains only. These
are computer controlled radios so I'm wondering if I need to adjust any
other parameters such as squelch (no pots to control squelch like the old
days) after making the Mic gain adjustments. Could the two be somehow
related through logic in the computer program that runs the radios?
I'm really stumped, any suggestions? Any UPS AT radio stack users have this
problem? How did you fix it? Should I run through the installation checkout
with the engine running so as to have more noise impinging on the microphone
while making adjustments? Don't like the idea of head down in the cockpit
with engine running but I can tie down the airplane while doing the checks
(I'm talking ground running here not trying to make adjustments in flight)!
Thanks for the help.
Dean Psiropoulos
RV-6A N197DM
Flying and tweeking.
Message 18
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Subject: | Re: Filter for Hand held devices |
Thanks Bob,
That does make sense; I had isolated it to the dc/dc converter in the same
manner that you suggest here- by powering the device internally. I knew
that it wasn't alternator noise since I was running off the a/c battery
only. I then found out that the same noise has presented itself on another
installation that I did, so it couldn't be installation specific. There the
owner simply let the Ipod charge up and then disconnected it from the system
and played the music into the audio system using the Ipod internal battery.
I'll try and get an isolation transformer here and see what effect that has;
it is simply a transformer with a 1:1 winding ratio?
Jay
-----Original Message-----
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Robert L.
Nuckolls, III
Sent: 21 September 2009 10:35 PM
Subject: RE: AeroElectric-List: Re: Filter for Hand held devices
<nuckolls.bob@aeroelectric.com>
At 08:11 AM 9/14/2009, you wrote:
>
>I think that I do need one; I am using a cigarette lighter type connection
>to power an Ipod power supply. When I connect this to the Ipod no noise is
>heard, but when I connect the Ipod to the radio/ intercom system I
>immediately get a high pitched noise in the earphones.
Okay, 'high pitched' is not alternator noise. It
MIGHT be an artifact of the dc/dc converter in your
ipod power adapter. Try first to power the Ipod internally
without the adapter. Does the noise go away? Try powering
the adapter fromits own 12 battery pack NOT connected to the a/c
in any way. A couple of el-cheeso 6v lantern batteries in
series a good diagnostic supply.
> I separated the
>power and signal leads and the noise stayed. I moved the power supply of
>the cigarette/ Ipod charger directly to the battery and the noise stayed.
I
>will still try a twisted pair on the power supply to the radio/intercom but
>it seems to me that the noise is generated by the Ipod charger so I thought
>that a filter might do the trick. Perhaps even a ferrite bead on the
>positive in to the radio will work.
>
>The only other thing that I can think of is that the loop formed by the
>plug->Ipod charger->Ipod audio out->radio/intercom is somehow causing the
>problem; but how does one get rid of that loop- its intrinsic to the music
>input?
It's most likely to be a ground loop issue which will be
re-enforced or denied by the above experiments.
In any case, it's almost a certainty that filtering
is not solution for root cause.
We may have to incorporate an isolation transformer
where audio from your Ipod goes to one winding and
audio to the ship's system is taken from the other
winding. See:
http://www.radioshack.com/product/index.jsp?productId=2103994
Bob . . .
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