microphone feedback

I connected a headset to the passenger jacks on my last flight for the first time and had some problems.
I get microphone feedback whenever I key either mic.
I checked to verify that it was not the headsets, it only occurs when a mic is plugged into the passenger jack and either PTT is activated, even with only one headset installed.
It does not interfere with the intercom.
The feedback is being transmitted because the tower called me on it.

Any Ideas where to start looking??

Gary

Is someone wearing the headset when feedback occurs? A person's head between the earphones blocks the sound from reaching the mic. Are the insulating washers installed to prevent the mic jack from contacting the aluminum seat?
Joe Gores

Check your grounding at the microphone jacks and the headphone jacks. The microphone jack MUST be insulated from the fuselage (using the insulating washer) and the headphone jack must be grounded to the fuselage at the jack. Use an ohmeter to verify the headphone jack.

If that does not work, ring out the wires to/from each jack to the back of the connector on the intercom.

Pilot Mic Sleeve = Pin 13
Pilot Mic Ring (Audio) - Pin 2
Pilot Headphone Tip = Pin 9
Pilot Headphone Ring = Pin 10
Pilot PTT = Pin 7

CoPilot Mic Sleeve = Pin 13
CoPilot Mic Ring (Audio) - Pin 3
CoPilot Headphone Tip = Pin 11
CoPilot Headphone Ring = Pin 12
CoPilot PTT = Pin 6

Thanks

Thanks for the info....

Will check it out.


Gary