Problems with headsets or the radio?
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Join Date: Jul 2001
Location: N.E. Derbyshire, UK
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Problems with headsets or the radio?
Not sure if this belongs on a tech. forum or Private Flying (BRL - feel free to move if you see fit).
I fly a 172 and use three Avcomm headsets (more or less the same models, but purchased at different times). The headsets all work perfectly as they are nearly new. I've had no problems with compatibility with other headsets I've occasionally borrowed for a 3rd passenger when all the seats have been full.
Recently, I've had problems with one of the radios in the 172. The problem is major distortion and interference, but only seems to be an issue with the engine running. If I make a call to the tower before startup, I get "readability 5". With the engine running this can be as low as "3" when right next to the tower, and the last time I flew it was "unreadable" as I entered the runway to backtrack.
I've tried just using one headset at a time - same result with each one. This suggests that the problem lies with the radio and not the headsets - perhaps some kind of suppressor failure? I'm not a techie and don't know the particular model of radio (Bendix King I think - that's about all I know).
The odd thing is that everyone else who flies the 'plane never has a problem. Always "readability 5" so they tell me.
And when I switch over to the second radio everything is perfect - it's just COM1 that gives me the trouble (COM2 is the original Cessna radio and whilst it's fine, it doesn't have the frequency toggle etc of COM1). Clearly I can fly with one radio working ok (I'm only a VFR daytime pilot) but I'd like to understand what the issue is (or might be) so I can point the owner in the right direction. He has had the radio tested (including a bench test) and no-one can replicate the problems I have every time I fly!
Any wise owls out there with any ideas?
Thanks!
I fly a 172 and use three Avcomm headsets (more or less the same models, but purchased at different times). The headsets all work perfectly as they are nearly new. I've had no problems with compatibility with other headsets I've occasionally borrowed for a 3rd passenger when all the seats have been full.
Recently, I've had problems with one of the radios in the 172. The problem is major distortion and interference, but only seems to be an issue with the engine running. If I make a call to the tower before startup, I get "readability 5". With the engine running this can be as low as "3" when right next to the tower, and the last time I flew it was "unreadable" as I entered the runway to backtrack.
I've tried just using one headset at a time - same result with each one. This suggests that the problem lies with the radio and not the headsets - perhaps some kind of suppressor failure? I'm not a techie and don't know the particular model of radio (Bendix King I think - that's about all I know).
The odd thing is that everyone else who flies the 'plane never has a problem. Always "readability 5" so they tell me.
And when I switch over to the second radio everything is perfect - it's just COM1 that gives me the trouble (COM2 is the original Cessna radio and whilst it's fine, it doesn't have the frequency toggle etc of COM1). Clearly I can fly with one radio working ok (I'm only a VFR daytime pilot) but I'd like to understand what the issue is (or might be) so I can point the owner in the right direction. He has had the radio tested (including a bench test) and no-one can replicate the problems I have every time I fly!
Any wise owls out there with any ideas?
Thanks!
Join Date: Sep 2004
Location: Leeds
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Have YOU tried it with different types of headset??
I have noticed that with Avcomm headsets the mic or the leads pick up the radiated transmit signal, which can cause a feedback or squeal in the sidetone, use a David Clark or similar and the transmissions are fine.
This happens when you have a SPA400 intercom with the insulated mic sockets.
At the low end of the freq band you will find it ok, the top end poor transmissions.
Make sure the antenna system for that radio is ok, and get a Avionics Eng to do a VSWR check.
Make sure that the mic sockets are ground properly.
It is one of these silly radio things!!
I have noticed that with Avcomm headsets the mic or the leads pick up the radiated transmit signal, which can cause a feedback or squeal in the sidetone, use a David Clark or similar and the transmissions are fine.
This happens when you have a SPA400 intercom with the insulated mic sockets.
At the low end of the freq band you will find it ok, the top end poor transmissions.
Make sure the antenna system for that radio is ok, and get a Avionics Eng to do a VSWR check.
Make sure that the mic sockets are ground properly.
It is one of these silly radio things!!
