[TowerTalk] Balun Recommendation

[Rick Stealey]

Would a current balun (choke?) be a possible solution to a problem of "RF on your audio, OM" in my mobile installation?
I'm planning to try one on the coax line either at the antenna end or the transceiver end.
My 20 meter Hamstick antenna is mounted on the rear deck of a sedan with one of those triple magnet mounts.
I have the frame of it tied to the car chassis with a copper strap.  If I move the antenna to the roof
it clears up the audio, but I don't want to operate with an 8 ft whip on top of the car.
I also have a 2.4 inch ferrite #31 toroid on order to install on the 12 volt power cable.
But I'm wondering if I need to also treat the microphone cable.  Is there a straightforward way to determine
what's causing the problem?

Rick  k2XT