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Radio Noise

 
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jluckey(at)pacbell.net
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PostPosted: Mon Sep 25, 2023 10:14 am    Post subject: Radio Noise Reply with quote
Seeking with wisdom of the Collective.
I'm hearing an intermittent "crackle" in the audio of an ICOM com radio but only when engine is running. It is not ignition noise.  I know this because when I turn-off the squelch, I can hear the Ignition "ripple" in the background. This "crackle" is a different sound.  (sorry, it's hard to describe sounds with words)

Environment:
Older ICOM A200 Com radio

There is a Dynon intercom in the system.
Old Narco transponder

2-place airplane, headsets only, no speaker
IO-360 with conventional mags

Symptoms:
1. A loud short-duration "crackle" occurs randomly every 3 to 10 seconds accompanied by a RECEIVE indication on the face of the radio.
2. Only happens when engine is running
3. This "crackle" is breaking squelch

My first guess was a loose connection in the antenna circuit. I have checked the antenna connection at the antenna and it appears to be OK. The coax is split-out and soldered to the antenna. The solder connection looks good and nothing is loose at the antenna.
The radio is very difficult to get to. The airplane seems to have been "built around" the avionics.
I'm trying to check the easy stuff first before tearing-up the air frame to gain access to the radio.
Suggestions?


Cheers,
-Jeff

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finn.lassen(at)verizon.ne
Guest
PostPosted: Mon Sep 25, 2023 11:49 am    Post subject: Radio Noise Reply with quote
Do you have strobes installed and on when you hear that?

Independent of engine RPM (vibrations)?

Finn

On 9/25/2023 2:13 PM, Jeff Luckey wrote:

Quote:
Seeking with wisdom of the Collective.


I'm hearing an intermittent "crackle" in the audio of an ICOM com radio but only when engine is running.  It is not ignition noise.  I know this because when I turn-off the squelch, I can hear the Ignition "ripple" in the background.  This "crackle" is a different sound.  (sorry, it's hard to describe sounds with words)



Environment:
Older ICOM A200 Com radio

There is a Dynon intercom in the system.
Old Narco transponder

2-place airplane, headsets only, no speaker
IO-360 with conventional mags







Symptoms:
1. A loud short-duration "crackle" occurs randomly every 3 to 10 seconds accompanied by a RECEIVE indication on the face of the radio.
2. Only happens when engine is running
3. This "crackle" is breaking squelch



My first guess was a loose connection in the antenna circuit.  I have checked the antenna connection at the antenna and it appears to be OK.  The coax is split-out and soldered to the antenna.  The solder connection looks good and nothing is loose at the antenna.


The radio is very difficult to get to.  The airplane seems to have been "built around" the avionics.  


I'm trying to check the easy stuff first before tearing-up the air frame to gain access to the radio.


Suggestions?




Cheers,


-Jeff






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nuckolls.bob(at)aeroelect
Guest
PostPosted: Mon Sep 25, 2023 12:46 pm    Post subject: Radio Noise Reply with quote
Quote:
Symptoms:
1. A loud short-duration "crackle" occurs randomly every 3 to 10 seconds accompanied by a RECEIVE indication on the face of the radio.

This suggests that the noise is coming in thru
the antenna. Try disconnecting the antenna to
see if noise goes away. Also, noises coming in
thru this pathway are affected by the radio's
volume control.

Quote:
2. Only happens when engine is running

Does turning alternator on/off make and difference?

Does running one mag at a time make a difference?




Bob . . .

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of the-best-we-know-how-to-do based
on physics and good practice.

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