HI Guys

I have a 10m CRT 6900N, nice little radio, does what I need it for, however, the audio is terible with the standard mic and I was recommended a KPO DMC 110, however I am a little flummoxed, the radio has a no connection pin, it supplies a voltage, and a TX, Audio and common, but no RX? the mic has AF, GND, RX and TX, my question is where do I stick the RX? keep it clean guys, your help would be really appreciated, its sending me around the twist as they say.