[rebel-builders] radio noise

Bob Patterson · Post by **Bob Patterson** » Sun Feb 19, 2012 10:47 am

Hi Cec !

I've run into the ICOM thing with their PTT's - you DO need THEIR
switches (and they're a bit pricey !) - they have been like this for
many years ! Thought the new ones were supposed to use standard
stuff - guess not ...

Is it a crackle, or a whine ?? Does it get worse with RPM,
or with airspeed ??? This will give clues - if it's a whine, and
gets worse when you turn on landing and/or nav lights, or strobes,
it's most likely alternator noise, and can be eliminated with
a filter. If it's a crackle, it could be a loose electrical connection,
bad PTT, or your mike is too sensitive, and is picking up wind noise,
etc. - sometimes (often !) intercoms just do not match radios, and there
is a clash of squelch functions --- try the radio without the intercom,
and on it's internal battery, instead of hooked to the cigarette lighter.
That will eliminate a couple of possibilities.

If it's a pop that changes with RPM, you could have a bad plug
lead (or 2 ...) - be good to check them over.

Sounds like the first thing would be to get the proper ICOM
wiring harness & PTT switch - you might be amazed !

......bobp

-------------------------------orig.-------------------------
On Thursday 11 May 2006 01:31 am, british thunder wrote:

I started to get allot of static through the com and the radio.
so I bought a new com and now Icom A6.
the static is still there ( BAD )
If I touch the rubber antenna it lets up a lot, If I have it on the
external antenna it is unbearable. and the com is almost unusable, too much
static and noise when you talk. It wasn't this bad last year only when the
battery was really low. On top of all this I cannot transmit only receive.
I talked to ICOM they said it was noise from the mags or the alt. and I
have to buy there ptt switch to be able to transmit. Any ideas or
solutions??
Has anyone delta with this??
Thanks
Cec
014R

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british thunder · Post by **british thunder** » Sun Feb 19, 2012 10:47 am

Thanks Bob.
the strobe and nav lights don't seem to affect it.
Cant remember if rpm does?
Think I got fed up before that, work clear when engine not running, good as
long as I stay on the ground.
I figured if I had a bad wire it would show up in the mag test on run up
but nothing.
Icom thinks it might have to do with the points in the mags??
I will check the wires and rpm this week if get good enough weather, looks
like rain all next week, go figure I'm off all week.
thanks
Cec
014R

----- Original Message -----
From: "Bob Patterson" <beep@sympatico.ca>
To: <rebel-builders@dcsol.com>
Sent: Wednesday, May 10, 2006 3:47 PM
Subject: Re: [rebel-builders] radio noise

Hi Cec !

I've run into the ICOM thing with their PTT's - you DO need THEIR
switches (and they're a bit pricey !) - they have been like this for
many years ! Thought the new ones were supposed to use standard
stuff - guess not ...

Is it a crackle, or a whine ?? Does it get worse with RPM,
or with airspeed ??? This will give clues - if it's a whine, and
gets worse when you turn on landing and/or nav lights, or strobes,
it's most likely alternator noise, and can be eliminated with
a filter. If it's a crackle, it could be a loose electrical connection,
bad PTT, or your mike is too sensitive, and is picking up wind noise,
etc. - sometimes (often !) intercoms just do not match radios, and there
is a clash of squelch functions --- try the radio without the intercom,
and on it's internal battery, instead of hooked to the cigarette lighter.
That will eliminate a couple of possibilities.

If it's a pop that changes with RPM, you could have a bad plug
lead (or 2 ...) - be good to check them over.

Sounds like the first thing would be to get the proper ICOM
wiring harness & PTT switch - you might be amazed !

......bobp

-------------------------------orig.-------------------------
On Thursday 11 May 2006 01:31 am, british thunder wrote:
I started to get allot of static through the com and the radio.
so I bought a new com and now Icom A6.
the static is still there ( BAD )
If I touch the rubber antenna it lets up a lot, If I have it on the
external antenna it is unbearable. and the com is almost unusable, too

much

static and noise when you talk. It wasn't this bad last year only when

the

battery was really low. On top of all this I cannot transmit only

receive.

I talked to ICOM they said it was noise from the mags or the alt. and I
have to buy there ptt switch to be able to transmit. Any ideas or
solutions??
Has anyone delta with this??
Thanks
Cec
014R

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Bill Maxwell · Post by **Bill Maxwell** » Sun Feb 19, 2012 10:47 am

hmmm, if you cant transmit then it sounds like you have an antenna
connection problem or a mis-wired PTT/ microphone combination. Ignition or
alternator noise wont stop a transmission, it usually just gets superimposed
on the voice audio and transmitted with it for all the world to hear. That
noise suggests inadequate shielding of the mic and phone connections. It
shouldn't be necessary to use Icoms own PTT switch etc, provided adequate
shielding of the audio lines is carried out, although having said that, I am
not familiar with the A6 but I am with the A200, the old A20Mk2, the A22
etc, all of which can be made to work perfectly with home built cabling and
PTT.

Bill
----- Original Message -----
From: "british thunder" <britishthunder@sympatico.ca>
To: <rebel-builders@dcsol.com>
Sent: Thursday, May 11, 2006 11:31 AM
Subject: [rebel-builders] radio noise

I started to get allot of static through the com and the radio.
so I bought a new com and now Icom A6.
the static is still there ( BAD )
If I touch the rubber antenna it lets up a lot, If I have it on the
external antenna it is unbearable. and the com is almost unusable, too
much static and noise when you talk.
It wasn't this bad last year only when the battery was really low.
On top of all this I cannot transmit only receive.
I talked to ICOM they said it was noise from the mags or the alt. and I
have to buy there ptt switch to be able to transmit.
Any ideas or solutions??
Has anyone delta with this??
Thanks
Cec
014R

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Bob Patterson · Post by **Bob Patterson** » Sun Feb 19, 2012 10:47 am

You're absolutely right, Bill. It's almost certainly a shielding/
bad wiring problem that is stopping the transmission, and it may be
allowing the noise leakage as well ... From trying to homebrew one on
my old A22, I can see what Cec is up against ... While it IS possible
to 'do it yourself', I gave up and just bought the ICOM stuff - it
worked perfectly, as it should !!

Does sound like new condensers for the mag points wouldn't hurt ...

......bobp
-------------------------------orig.-------------------------
On Thursday 11 May 2006 01:12 am, Bill Maxwell wrote:

hmmm, if you cant transmit then it sounds like you have an antenna
connection problem or a mis-wired PTT/ microphone combination. Ignition or
alternator noise wont stop a transmission, it usually just gets
superimposed on the voice audio and transmitted with it for all the world
to hear. That noise suggests inadequate shielding of the mic and phone
connections. It shouldn't be necessary to use Icoms own PTT switch etc,
provided adequate shielding of the audio lines is carried out, although
having said that, I am not familiar with the A6 but I am with the A200, the
old A20Mk2, the A22 etc, all of which can be made to work perfectly with
home built cabling and PTT.

Bill
----- Original Message -----
From: "british thunder" <britishthunder@sympatico.ca>
To: <rebel-builders@dcsol.com>
Sent: Thursday, May 11, 2006 11:31 AM
Subject: [rebel-builders] radio noise

I started to get allot of static through the com and the radio.
so I bought a new com and now Icom A6.
the static is still there ( BAD )
If I touch the rubber antenna it lets up a lot, If I have it on the
external antenna it is unbearable. and the com is almost unusable, too
much static and noise when you talk.
It wasn't this bad last year only when the battery was really low.
On top of all this I cannot transmit only receive.
I talked to ICOM they said it was noise from the mags or the alt. and I
have to buy there ptt switch to be able to transmit.
Any ideas or solutions??
Has anyone delta with this??
Thanks
Cec
014R

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Bill Maxwell · Post by **Bill Maxwell** » Sun Feb 19, 2012 10:47 am

Yes, Icom stuff ceratinly should work out of the box, as they say. One
problem I have encountered in trying to use an A20 ( if memory serves )
where an A200 had gone before was the different PTT wiring itself. In the
A200, the PTT line is grounded, while the pilot's mic is simultaneously
switched from the intercom to coms pin. The hand held that my friend was
trying to use in its stead simply grounded the mic switch to achieve both
mic and ptt switching. Something similar might be going on with Cec's
installation. Just a thought ....

Bill
----- Original Message -----
From: "Bob Patterson" <beep@sympatico.ca>
To: <rebel-builders@dcsol.com>
Sent: Thursday, May 11, 2006 10:00 AM
Subject: Re: [rebel-builders] radio noise

You're absolutely right, Bill. It's almost certainly a shielding/
bad wiring problem that is stopping the transmission, and it may be
allowing the noise leakage as well ... From trying to homebrew one on
my old A22, I can see what Cec is up against ... While it IS possible
to 'do it yourself', I gave up and just bought the ICOM stuff - it
worked perfectly, as it should !!

Does sound like new condensers for the mag points wouldn't hurt ...

......bobp
-------------------------------orig.-------------------------
On Thursday 11 May 2006 01:12 am, Bill Maxwell wrote:
hmmm, if you cant transmit then it sounds like you have an antenna
connection problem or a mis-wired PTT/ microphone combination. Ignition
or
alternator noise wont stop a transmission, it usually just gets
superimposed on the voice audio and transmitted with it for all the world
to hear. That noise suggests inadequate shielding of the mic and phone
connections. It shouldn't be necessary to use Icoms own PTT switch etc,
provided adequate shielding of the audio lines is carried out, although
having said that, I am not familiar with the A6 but I am with the A200,
the
old A20Mk2, the A22 etc, all of which can be made to work perfectly with
home built cabling and PTT.

Bill
----- Original Message -----
From: "british thunder" <britishthunder@sympatico.ca>
To: <rebel-builders@dcsol.com>
Sent: Thursday, May 11, 2006 11:31 AM
Subject: [rebel-builders] radio noise

I started to get allot of static through the com and the radio.
so I bought a new com and now Icom A6.
the static is still there ( BAD )
If I touch the rubber antenna it lets up a lot, If I have it on the
external antenna it is unbearable. and the com is almost unusable, too
much static and noise when you talk.
It wasn't this bad last year only when the battery was really low.
On top of all this I cannot transmit only receive.
I talked to ICOM they said it was noise from the mags or the alt. and I
have to buy there ptt switch to be able to transmit.
Any ideas or solutions??
Has anyone delta with this??
Thanks
Cec
014R

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Ken · Post by **Ken** » Sun Feb 19, 2012 11:16 am

Mike

I don't have any radio noise from the engine but I don't have any nav
radios either. I have not shielded anything but the headset wires.
Chances are reasonable that your problem is something simple and easy to
fix once you isolate it.

First thing I'd suggest is to find out whether it is RF radiation or
coming through the power wiring. The aeroelectric book has a good
chapter on tracking this stuff but my suggestion would be to
temporarilly power a suspect device (nav receiver?) from a separate
battery to see if the noise is still there. A $30. self contained
booster battey thing from someplace like Wally-Mart is handy for stuff
like that (as well as powering a 120 volt inverter and my tools when I'm
at the hangar).

Static/popping may be ignition but even that can come via RF or through
the wiring. Whine that increases pitch with rpm is often alternator
noise from a bad diode.

Ken

Mike Kimball wrote:

This is for you guys using automotive engine conversions. I've got a fair
amount of radio noise that increases in pitch as engine RPM is increased.
This generally means the source is somewhere in the ignition system. I have
shielded the distributer pickup wires and the wires to the coils. I also
shielded the wires from the alternator to the main bus. All shielding is
grounded at one end. All headset jacks have isolators. I have spiral wrap
spark plug wires that are supposed to be good for RF suppression but they
are not shielded. For some reason the radio noise is much worse on the nav
side. My transmissions are loud and clear. Do any of you automotive
conversion folks have radio noise problems? What have you done to reduce
radio noise.

Mike
044SR

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N.Smith · Post by **N.Smith** » Sun Feb 19, 2012 11:16 am

Hi Mike
If you disconnect the alternator (I mean disconnect all wires and insulate
from the alternator) and run the engine and the noise is still there then it
is likely ignition based. If it's not there then its likely noise generated
in the rectifier/regulator on the alternator. Switcher regulators can be
very noisy, and a linear regulator can reduce that noise to almost zero. See
Aeroelectric connection book for stuff on that problem area.
Nig
745E

-----Original Message-----
From: mike.davis@dcsol.com [mailto:mike.davis@dcsol.com]On Behalf Of
Mike Kimball
Sent: 19 October 2006 02:42
To: Rebel Builder's List
Subject: [rebel-builders] Radio noise

This is for you guys using automotive engine conversions. I've got a fair
amount of radio noise that increases in pitch as engine RPM is increased.
This generally means the source is somewhere in the ignition system. I have
shielded the distributer pickup wires and the wires to the coils. I also
shielded the wires from the alternator to the main bus. All shielding is
grounded at one end. All headset jacks have isolators. I have spiral wrap
spark plug wires that are supposed to be good for RF suppression but they
are not shielded. For some reason the radio noise is much worse on the nav
side. My transmissions are loud and clear. Do any of you automotive
conversion folks have radio noise problems? What have you done to reduce
radio noise.

Mike
044SR

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Ken · Post by **Ken** » Sun Feb 19, 2012 11:16 am

Yes that will confirm if the noise is from the alternator.

I could be wrong of course but FWIW, certainly a linear regulator is
theoretically quieter but every vehicle I've ever owned has had a
switching regulator and that has never been a problem. The battery
should be quite sufficient for smoothing out the system when properly
wired unless there is something else going on. That said, I have no
doubt that the B and C linear regulator is an extremely reliable premium
product but I guess I don't believe that it will do anything that can't
be accomplished with decent electrical system design 99 times out of
100. Alternator fields often draw less current than the ignition coil
which generally implies less switching noise althought the frequencies
are likely different. Most airplanes are flying with switching regulators.

I guess I can imagine some remotely possible situations where a linear
regulator is the cure. Color me doubtful but always willing to learn...

Ken

N.Smith wrote:

Hi Mike
If you disconnect the alternator (I mean disconnect all wires and insulate
from the alternator) and run the engine and the noise is still there then it
is likely ignition based. If it's not there then its likely noise generated
in the rectifier/regulator on the alternator. Switcher regulators can be
very noisy, and a linear regulator can reduce that noise to almost zero. See
Aeroelectric connection book for stuff on that problem area.
Nig
745E

-----Original Message-----
From: mike.davis@dcsol.com [mailto:mike.davis@dcsol.com]On Behalf Of
Mike Kimball
Sent: 19 October 2006 02:42
To: Rebel Builder's List
Subject: [rebel-builders] Radio noise

This is for you guys using automotive engine conversions. I've got a fair
amount of radio noise that increases in pitch as engine RPM is increased.
This generally means the source is somewhere in the ignition system. I have
shielded the distributer pickup wires and the wires to the coils. I also
shielded the wires from the alternator to the main bus. All shielding is
grounded at one end. All headset jacks have isolators. I have spiral wrap
spark plug wires that are supposed to be good for RF suppression but they
are not shielded. For some reason the radio noise is much worse on the nav
side. My transmissions are loud and clear. Do any of you automotive
conversion folks have radio noise problems? What have you done to reduce
radio noise.

Mike
044SR

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Richard Wampach · Post by **Richard Wampach** » Sun Feb 19, 2012 11:16 am

How about trying the capacitor across the alternator A+ output lug to
ground as Cessna does. This was a must on an airplane with an ADF, but
helps reduce most other radio noise as well. It's over $30 from Cessna,
you can try Spruce or one of the other suppliers, or maybe an automotive
parts store.

Dick Wampach SR-108

-----Original Message-----
From: mike.davis@dcsol.com [mailto:mike.davis@dcsol.com] On Behalf Of
Ken
Sent: Thursday, October 19, 2006 9:18 AM
To: rebel-builders@dcsol.com
Subject: Re: [rebel-builders] Radio noise

Yes that will confirm if the noise is from the alternator.

I could be wrong of course but FWIW, certainly a linear regulator is
theoretically quieter but every vehicle I've ever owned has had a
switching regulator and that has never been a problem. The battery
should be quite sufficient for smoothing out the system when properly
wired unless there is something else going on. That said, I have no
doubt that the B and C linear regulator is an extremely reliable premium

product but I guess I don't believe that it will do anything that can't
be accomplished with decent electrical system design 99 times out of
100. Alternator fields often draw less current than the ignition coil
which generally implies less switching noise althought the frequencies
are likely different. Most airplanes are flying with switching
regulators.

I guess I can imagine some remotely possible situations where a linear
regulator is the cure. Color me doubtful but always willing to learn...

Ken

N.Smith wrote:

Hi Mike
If you disconnect the alternator (I mean disconnect all wires and

insulate

from the alternator) and run the engine and the noise is still there

then it

is likely ignition based. If it's not there then its likely noise

generated

in the rectifier/regulator on the alternator. Switcher regulators can

be

very noisy, and a linear regulator can reduce that noise to almost

zero. See

Aeroelectric connection book for stuff on that problem area.
Nig
745E

-----Original Message-----
From: mike.davis@dcsol.com [mailto:mike.davis@dcsol.com]On Behalf Of
Mike Kimball
Sent: 19 October 2006 02:42
To: Rebel Builder's List
Subject: [rebel-builders] Radio noise

This is for you guys using automotive engine conversions. I've got a

fair

amount of radio noise that increases in pitch as engine RPM is

increased.

This generally means the source is somewhere in the ignition system. I

have

shielded the distributer pickup wires and the wires to the coils. I

also

shielded the wires from the alternator to the main bus. All shielding

is

grounded at one end. All headset jacks have isolators. I have spiral

wrap

spark plug wires that are supposed to be good for RF suppression but

they

are not shielded. For some reason the radio noise is much worse on the

nav

side. My transmissions are loud and clear. Do any of you automotive
conversion folks have radio noise problems? What have you done to

reduce

radio noise.

Mike
044SR

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Ron Shannon · Post by **Ron Shannon** » Sun Feb 19, 2012 11:16 am

B & C has a good alternator filter kit for $33, at

http://tinyurl.com/y8foa6

Ron

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Mike Kimball · Post by **Mike Kimball** » Sun Feb 19, 2012 11:16 am

I forgot to mention that I have the Ameri-King AK-950 DC line filter on the
alternator output wire and the Amer-King AK-950-FTR1 alternator filter
(capacitor to ground from the alternator as suggested) and I later added the
"Eliminator" power line filter to the NAV/COM power input. The Eliminator
did help noticeably but there is still too much noise.

I'm quite interested in automotive engine conversions with respect to the
spark plug wires, coils, and distributer. Just using stock stuff or doing
something to shield RF. My avionics guy started talking about building a
box around the distributer and shielding the spark plug wires and stuff and
I thought, oh no, really?! I don't remember anything like that being
necessary on other conversions I've seen.

Oh yeah, just for thoroughness, I am using Taylor 409 spiral wrap spark plug
wires. One of the features of these wires as advertised by Taylor is low RF
interference. Of course, they are talking about car stereos, not aircraft
NAV/COMs.

Mike

-----Original Message-----
From: mike.davis@dcsol.com [mailto:mike.davis@dcsol.com] On Behalf Of
Richard Wampach
Sent: Thursday, October 19, 2006 9:41 AM
To: rebel-builders@dcsol.com
Subject: RE: [rebel-builders] Radio noise

How about trying the capacitor across the alternator A+ output lug to
ground as Cessna does. This was a must on an airplane with an ADF, but
helps reduce most other radio noise as well. It's over $30 from Cessna,
you can try Spruce or one of the other suppliers, or maybe an automotive
parts store.

Dick Wampach SR-108

-----Original Message-----
From: mike.davis@dcsol.com [mailto:mike.davis@dcsol.com] On Behalf Of
Ken
Sent: Thursday, October 19, 2006 9:18 AM
To: rebel-builders@dcsol.com
Subject: Re: [rebel-builders] Radio noise

Yes that will confirm if the noise is from the alternator.

I could be wrong of course but FWIW, certainly a linear regulator is
theoretically quieter but every vehicle I've ever owned has had a
switching regulator and that has never been a problem. The battery
should be quite sufficient for smoothing out the system when properly
wired unless there is something else going on. That said, I have no
doubt that the B and C linear regulator is an extremely reliable premium

product but I guess I don't believe that it will do anything that can't
be accomplished with decent electrical system design 99 times out of
100. Alternator fields often draw less current than the ignition coil
which generally implies less switching noise althought the frequencies
are likely different. Most airplanes are flying with switching
regulators.

I guess I can imagine some remotely possible situations where a linear
regulator is the cure. Color me doubtful but always willing to learn...

Ken

N.Smith wrote:

Hi Mike
If you disconnect the alternator (I mean disconnect all wires and

insulate

from the alternator) and run the engine and the noise is still there

then it

is likely ignition based. If it's not there then its likely noise

generated

in the rectifier/regulator on the alternator. Switcher regulators can

be

very noisy, and a linear regulator can reduce that noise to almost

zero. See

Aeroelectric connection book for stuff on that problem area.
Nig
745E

-----Original Message-----
From: mike.davis@dcsol.com [mailto:mike.davis@dcsol.com]On Behalf Of
Mike Kimball
Sent: 19 October 2006 02:42
To: Rebel Builder's List
Subject: [rebel-builders] Radio noise

This is for you guys using automotive engine conversions. I've got a

fair

amount of radio noise that increases in pitch as engine RPM is

increased.

This generally means the source is somewhere in the ignition system. I

have

shielded the distributer pickup wires and the wires to the coils. I

also

shielded the wires from the alternator to the main bus. All shielding

is

grounded at one end. All headset jacks have isolators. I have spiral

wrap

spark plug wires that are supposed to be good for RF suppression but

they

are not shielded. For some reason the radio noise is much worse on the

nav

side. My transmissions are loud and clear. Do any of you automotive
conversion folks have radio noise problems? What have you done to

reduce

radio noise.

Mike
044SR

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Ken · Post by **Ken** » Sun Feb 19, 2012 11:16 am

I have 10 Taylor spiral core ignition wires with no apparent ignition
noise in the intercom or com radio regardless of what combination of
ignitions that I use. It is very unusual to have a problem with those.
Shielding high voltage components will only help radiated noise. So far
I don't think you know that it is radiated RF noise. In fact if power
line filters helped at all, I think that indicates that it is likely NOT
radiated RF although more than one thing could be happening. Shielding
will not help with noise on the power line or magnetic cross coupling.

Note that all the band aid filters in the world won't help much if there
is a bad diode in the alternator. Shots in the dark may not be the best
way to troubleshoot this. I'd still probably try running the nav
receiver off an independant battery or at least try running the engine
with the alternator turned off or with its drive belt removed.

Ken

Mike Kimball wrote:

I forgot to mention that I have the Ameri-King AK-950 DC line filter on the
alternator output wire and the Amer-King AK-950-FTR1 alternator filter
(capacitor to ground from the alternator as suggested) and I later added the
"Eliminator" power line filter to the NAV/COM power input. The Eliminator
did help noticeably but there is still too much noise.

I'm quite interested in automotive engine conversions with respect to the
spark plug wires, coils, and distributer. Just using stock stuff or doing
something to shield RF. My avionics guy started talking about building a
box around the distributer and shielding the spark plug wires and stuff and
I thought, oh no, really?! I don't remember anything like that being
necessary on other conversions I've seen.

Oh yeah, just for thoroughness, I am using Taylor 409 spiral wrap spark plug
wires. One of the features of these wires as advertised by Taylor is low RF
interference. Of course, they are talking about car stereos, not aircraft
NAV/COMs.

Mike

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Bob Patterson · Post by **Bob Patterson** » Sun Feb 19, 2012 11:16 am

Hi Mike !

This might be a silly question, but how effective is the squelch
on your radio & intercom working ??? Might you have an open mike
connection somewhere ???? How about trying a different headset ??

May be 'way off there, but I've had some really unpleasant
experiences just from having 2 different makes of headsets - one
with a dynamic mike, and one old carbon mike !! Squelch would
break way too easily, and I suffered a deafening roar, while
my co-pilot could hardly hear the radio....

--
......bobp
http://bpatterson.qhealthbeauty.com
http://apatterson2.qhealthzone.com
http://apatterson2.qbeautyzone.com
-------------------------------orig.-------------------------
On Thursday 19 October 2006 11:42 pm, Mike Kimball wrote:

I forgot to mention that I have the Ameri-King AK-950 DC line filter on the
alternator output wire and the Amer-King AK-950-FTR1 alternator filter
(capacitor to ground from the alternator as suggested) and I later added the
"Eliminator" power line filter to the NAV/COM power input. The Eliminator
did help noticeably but there is still too much noise.

I'm quite interested in automotive engine conversions with respect to the
spark plug wires, coils, and distributer. Just using stock stuff or doing
something to shield RF. My avionics guy started talking about building a
box around the distributer and shielding the spark plug wires and stuff and
I thought, oh no, really?! I don't remember anything like that being
necessary on other conversions I've seen.

Oh yeah, just for thoroughness, I am using Taylor 409 spiral wrap spark plug
wires. One of the features of these wires as advertised by Taylor is low RF
interference. Of course, they are talking about car stereos, not aircraft
NAV/COMs.

Mike

-----Original Message-----
From: mike.davis@dcsol.com [mailto:mike.davis@dcsol.com] On Behalf Of
Richard Wampach
Sent: Thursday, October 19, 2006 9:41 AM
To: rebel-builders@dcsol.com
Subject: RE: [rebel-builders] Radio noise

How about trying the capacitor across the alternator A+ output lug to
ground as Cessna does. This was a must on an airplane with an ADF, but
helps reduce most other radio noise as well. It's over $30 from Cessna,
you can try Spruce or one of the other suppliers, or maybe an automotive
parts store.

Dick Wampach SR-108

-----Original Message-----
From: mike.davis@dcsol.com [mailto:mike.davis@dcsol.com] On Behalf Of
Ken
Sent: Thursday, October 19, 2006 9:18 AM
To: rebel-builders@dcsol.com
Subject: Re: [rebel-builders] Radio noise

Yes that will confirm if the noise is from the alternator.

I could be wrong of course but FWIW, certainly a linear regulator is
theoretically quieter but every vehicle I've ever owned has had a
switching regulator and that has never been a problem. The battery
should be quite sufficient for smoothing out the system when properly
wired unless there is something else going on. That said, I have no
doubt that the B and C linear regulator is an extremely reliable premium

product but I guess I don't believe that it will do anything that can't
be accomplished with decent electrical system design 99 times out of
100. Alternator fields often draw less current than the ignition coil
which generally implies less switching noise althought the frequencies
are likely different. Most airplanes are flying with switching
regulators.

I guess I can imagine some remotely possible situations where a linear
regulator is the cure. Color me doubtful but always willing to learn...

Ken

N.Smith wrote:

Hi Mike
If you disconnect the alternator (I mean disconnect all wires and
insulate
from the alternator) and run the engine and the noise is still there
then it
is likely ignition based. If it's not there then its likely noise
generated
in the rectifier/regulator on the alternator. Switcher regulators can
be
very noisy, and a linear regulator can reduce that noise to almost
zero. See
Aeroelectric connection book for stuff on that problem area.
Nig
745E

-----Original Message-----
From: mike.davis@dcsol.com [mailto:mike.davis@dcsol.com]On Behalf Of
Mike Kimball
Sent: 19 October 2006 02:42
To: Rebel Builder's List
Subject: [rebel-builders] Radio noise

This is for you guys using automotive engine conversions. I've got a
fair
amount of radio noise that increases in pitch as engine RPM is
increased.
This generally means the source is somewhere in the ignition system. I
have
shielded the distributer pickup wires and the wires to the coils. I
also
shielded the wires from the alternator to the main bus. All shielding
is
grounded at one end. All headset jacks have isolators. I have spiral
wrap
spark plug wires that are supposed to be good for RF suppression but
they
are not shielded. For some reason the radio noise is much worse on the
nav
side. My transmissions are loud and clear. Do any of you automotive
conversion folks have radio noise problems? What have you done to
reduce
radio noise.

Mike
044SR

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Mike Kimball · Post by **Mike Kimball** » Sun Feb 19, 2012 11:16 am

Yep. I need to try eliminating the alternator. I had the alternator tested
on NAPA's machine before I installed it and it passed then but you never
know. I could have lost a diode since then. I only just got the engine
running again so I can return to chasing radio noise. It looks possible
that my fuel pump is pushing the float needle off the seat and causing
problems. I am only reading 6 psi at the carb so I'm a little surprised but
I had much better luck starting and running the engine at low RPM with the
fuel pumps off, gravity feed only. However, the engine will not run above
3000 RPM unless I turn a fuel pump on. Unless I want to adopt a fuel pump
off at low RPM and on at high RPM operating technique I guess I'll need to
add a fuel pressure regulator. I'm off to NAPA for a pressure regulator.
Thanks for the tips on radio noise Ken and Bob. In answer to Bob's
suggestions, my comm does not have a squelch but the audio panel does and
seems to be working properly. I am using a 30 year old David Clark right
now but I definitely plan an upgrade. No stuck mike problem.

Mike

-----Original Message-----
From: mike.davis@dcsol.com [mailto:mike.davis@dcsol.com] On Behalf Of Ken
Sent: Friday, October 20, 2006 4:11 AM
To: rebel-builders@dcsol.com
Subject: Re: [rebel-builders] Radio noise

I have 10 Taylor spiral core ignition wires with no apparent ignition
noise in the intercom or com radio regardless of what combination of
ignitions that I use. It is very unusual to have a problem with those.
Shielding high voltage components will only help radiated noise. So far
I don't think you know that it is radiated RF noise. In fact if power
line filters helped at all, I think that indicates that it is likely NOT
radiated RF although more than one thing could be happening. Shielding
will not help with noise on the power line or magnetic cross coupling.

Note that all the band aid filters in the world won't help much if there
is a bad diode in the alternator. Shots in the dark may not be the best
way to troubleshoot this. I'd still probably try running the nav
receiver off an independant battery or at least try running the engine
with the alternator turned off or with its drive belt removed.

Ken

Mike Kimball wrote:

I forgot to mention that I have the Ameri-King AK-950 DC line filter on the
alternator output wire and the Amer-King AK-950-FTR1 alternator filter
(capacitor to ground from the alternator as suggested) and I later added

the

"Eliminator" power line filter to the NAV/COM power input. The Eliminator
did help noticeably but there is still too much noise.

I'm quite interested in automotive engine conversions with respect to the
spark plug wires, coils, and distributer. Just using stock stuff or doing
something to shield RF. My avionics guy started talking about building a
box around the distributer and shielding the spark plug wires and stuff and
I thought, oh no, really?! I don't remember anything like that being
necessary on other conversions I've seen.

Oh yeah, just for thoroughness, I am using Taylor 409 spiral wrap spark

plug

wires. One of the features of these wires as advertised by Taylor is low

RF

interference. Of course, they are talking about car stereos, not aircraft
NAV/COMs.

Mike

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Brian · Post by **Brian** » Sun Feb 19, 2012 11:16 am

Mike - get a Bose Headset!

Brian

-----Original Message-----
From: mike.davis@dcsol.com [mailto:mike.davis@dcsol.com] On Behalf Of Mike
Kimball
Sent: Friday, October 20, 2006 10:14 PM
To: rebel-builders@dcsol.com
Subject: RE: [rebel-builders] Radio noise

Yep. I need to try eliminating the alternator. I had the alternator tested
on NAPA's machine before I installed it and it passed then but you never
know. I could have lost a diode since then. I only just got the engine
running again so I can return to chasing radio noise. It looks possible
that my fuel pump is pushing the float needle off the seat and causing
problems. I am only reading 6 psi at the carb so I'm a little surprised but
I had much better luck starting and running the engine at low RPM with the
fuel pumps off, gravity feed only. However, the engine will not run above
3000 RPM unless I turn a fuel pump on. Unless I want to adopt a fuel pump
off at low RPM and on at high RPM operating technique I guess I'll need to
add a fuel pressure regulator. I'm off to NAPA for a pressure regulator.
Thanks for the tips on radio noise Ken and Bob. In answer to Bob's
suggestions, my comm does not have a squelch but the audio panel does and
seems to be working properly. I am using a 30 year old David Clark right
now but I definitely plan an upgrade. No stuck mike problem.

Mike

-----Original Message-----
From: mike.davis@dcsol.com [mailto:mike.davis@dcsol.com] On Behalf Of Ken
Sent: Friday, October 20, 2006 4:11 AM
To: rebel-builders@dcsol.com
Subject: Re: [rebel-builders] Radio noise

I have 10 Taylor spiral core ignition wires with no apparent ignition
noise in the intercom or com radio regardless of what combination of
ignitions that I use. It is very unusual to have a problem with those.
Shielding high voltage components will only help radiated noise. So far
I don't think you know that it is radiated RF noise. In fact if power
line filters helped at all, I think that indicates that it is likely NOT
radiated RF although more than one thing could be happening. Shielding
will not help with noise on the power line or magnetic cross coupling.

Note that all the band aid filters in the world won't help much if there
is a bad diode in the alternator. Shots in the dark may not be the best
way to troubleshoot this. I'd still probably try running the nav
receiver off an independant battery or at least try running the engine
with the alternator turned off or with its drive belt removed.

Ken

Mike Kimball wrote:

I forgot to mention that I have the Ameri-King AK-950 DC line filter on the
alternator output wire and the Amer-King AK-950-FTR1 alternator filter
(capacitor to ground from the alternator as suggested) and I later added

the

"Eliminator" power line filter to the NAV/COM power input. The Eliminator
did help noticeably but there is still too much noise.

I'm quite interested in automotive engine conversions with respect to the
spark plug wires, coils, and distributer. Just using stock stuff or doing
something to shield RF. My avionics guy started talking about building a
box around the distributer and shielding the spark plug wires and stuff and
I thought, oh no, really?! I don't remember anything like that being
necessary on other conversions I've seen.

Oh yeah, just for thoroughness, I am using Taylor 409 spiral wrap spark

plug

wires. One of the features of these wires as advertised by Taylor is low

RF

interference. Of course, they are talking about car stereos, not aircraft
NAV/COMs.

Mike

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