This sounds like inadequate isolation in the audio source switching of
the audio panel. Most of modern audio panels (King, PSE, RST) do not
intrisically have this problem. I think you have a PSE, which shouldn't
do this.

Actually, I have a Narco CP-136 audio panel.

(See a picture of this model at http://www.ronhahn.com/Hawk-XP/CP136.html )

For further diagnosis, I'll bet that if you turn the volume control of
the non-selected comm radio down, then the bleedthrough will go away.

Yep, I believe it does. So this means the audio panel is wired incorrectly?

Also try switching the non-selected com receiver to the overhead speaker
while listening to the primary com on the ANR headsets, and report back.

Okay, will do. I should expect to hear the AWOS broadcasting quietly on the
speaker, I presume, same as I hear in my headset?
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"