GTR 225 & PM3000 Transmit Noise

Hi All

I have a Garmin 225 8.33 Radio coupled with the PM3000 Intercom. The intercom works fine and it receives transmissions fine. When I transmit, I get a ringing/clanging sound in my ears through the headset sidetone.

I have read other posts on the forum about turning the sidetone down to zero. I have been into the GTR 225 menu and have done this but it still is the same.

Any ideas where I can find the cause of this issue? My wiring was originally for a D180 and I converted it to the Skyview wiring for the Skyview D1000 system. - Thanks to Bill H for this - I could not have done this without reading his excellent posts!.

Having no radio/electrical background, I'm flumuxed - Any advice on where to start looking for the cause of my problem?

Regards

Anthony

The usual techniques are:
1. Try easy stuff first, no matter how unlikely. You've already started by turning down the sidetone volume to zero.
2. Divide and conquer. Disconnect the side tone wire from behind the intercom. If the problem remains, then the RF is being picked up somewhere else, you may have to disconnect wires one at a time until you find the culprit, then go from there. If the problem goes away with the sidetone disconnected, then figure out how the signal is getting into that wire. etc. It can be painstaking.

I'm assuming you don't have a second radio which could be the source of the signal.

Thanks Bob. I've only got one radio so it is a bit easier. I vaguely remember having to splice either the intercom wires or the PTT wires in the avionics bay. I'll have a look here and work back and forwards from there.

Anthony

I said "sidetone wire" as if it were something separate. On the Garmin the sidetone is carried on the com audio output wire.
Not sure there should be any need for splicing wires(?) unless some were just too short.

Make sure the radio is fully seated in its tray. Also check the radio antenna coax cable, especially the connectors on each end.
The headset jacks should not be grounded at the seat floor.
If you have a music input jack, try disconnecting it at the panel end.