In spite of my agreement with most of the flames thrown at you about this,
there are certain applications where "curtesy tone" is warranted - as few as
they may be.

So that out of the way, often the RX is used to enable/mute the audio If the
RX is pulled low, it enables the audio path to the audio output. If open it
will mute.


"Ken C" wrote in message
...
I am trying to adapt a CB "roger beep" mic for ham radio and there is
some odd terminology for CB mic wiring.

The CB'ers call "PTT" "transmit (TX)"

They call "audio-out" "audio" (not too bad)

They have a separate line for "receive (RX)" which some call "receive
control." What is that for? Anyone know? By testing, I know it is
not for a speaker in the mic. It shows 6 ohms to ground.

Ken KC2JDY