squealing Plantronic mic

Howdy,

Has anyone experienced a squealing plantronics headset mic? Ours was
replaced by the company and started squealing again. It is hooked into
a Becker 4201 which was tweaked by the factory as a troubleshooting
measure. It seems like the mic is being affected by the antenna RF. If
I hold it below the cockpit outside, it improves. Used to work just
fine. Don't know what happened. Any ideas?

BTW, the side tone is turned off.

Tim

The last time I had this problem (with a homemade Les Sebald-designed
clip-on mic), I search high and low in the mic circuit and didn't find
the problem. It turned out that it was caused by a bad connection in
the antenna cable. The problem went away when I cleaned all the BNC
connections and the antenna ground terminal attachment.

Just a thought. Good luck!

Bob K.

Thanks, Bob. I'll give the connections a good going-over and see what
happens....

Cheers,
Tim




Bob Kuykendall wrote:
The last time I had this problem (with a homemade Les Sebald-designed
clip-on mic), I search high and low in the mic circuit and didn't find
the problem. It turned out that it was caused by a bad connection in
the antenna cable. The problem went away when I cleaned all the BNC
connections and the antenna ground terminal attachment.

Just a thought. Good luck!

Bob K.

wrote:
Howdy,

Has anyone experienced a squealing plantronics headset mic?

Around here, they never live that long. We hate stoolies.

Tony V.
:-)

Mike problems could be caused by the antenna as Bob suggests, or it could be
caused by a ground loop.

A ground loop in the mike circuit might occur if there is more than one
grounding point - for example where the shielded mike cable is grounded at
the radio and also grounded at the metal panel where the mike connector is
mounted.

Sometimes simply insulating the mike connector from the panel will cure the
problem.

Colin