I've become irritated with the crackling noise my transponder (King 76C) gives
off into my headset when turned on.  I've got the Bose X headset.  The
transponder antenna is a blade type mounted on the belly under the co-pilot
seat.  There's a small ground plane installed. Can someone advise where I
should begin to look to isolate and stop this noise?  This is an e-glass 360.

Ed de Chazal
N361DC