Clearcom to M1


Nov 17, 2014

I'm trying to make my Motorola PMMN4013a 2-way radio speaker/mic play nice with my Clearcom unit, standard 4-pin. I soldered it up based on another thread here ( )- got input to the unit (but PTT was disabled) and no output. I wired it using what standard wire colors to the pinout made sense, but no cigar. My wire colors are:
Black, White, Red, Blue

Has anyone had success with this? Any help? The audio engineer in me wants to think this would be easy....

Thanks, jw


CB Mods
Premium Member
Departed Member
Jul 15, 2005
Sydney, Australia
I've moved your thread over to the Sound (and Intercom) forum, please do drop back to the New Members Board to introduce yourself.

The pinout listed in that other thread is accurate, the challenge is working out how the Motorola device is wired, colour codes are at the whim of the manufacturer...

If it's assembled with screws, then opening up the other end might be a worthwhile step. Otherwise get out a multimeter on ohms and start looking at resistance on wire combinations.

With 4 wires, you will PROBABLY have a pair for mic and a pair for speaker, but you MIGHT have a common ground for all of it, and single wires for mic, speaker and PTT.

***This is a general approach, see note below***
The speaker wires will be the easiest to find, look for a DC resistance in the order of Ohms.
Then I'd probably go looking for PTT, see if holding down the switch shorts or changes any of the resistances you found in looking for the speaker (so write them down as you go).
You should then be able to go through a process of elimination on the mic.

But since you have a working mic input, you can change your approach. What resistance are you seeing between the 2 non mic wires?
What about between current mic wire 1 and each of the others and again with mic wire 2?
Repeat with a rubber band holding the PTT switch down (or a willing volunteer)

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