Dave (W7AQK), if the microphone you are referring to is for the K3, then it works perfectly with the low cost Kenwood MC-43S fist microphone (UK price £19.95 or so). I have the microphone selection as "FP.H" in the K3 menu and a mic gain of 40. Excellent audio reports. 73 Dave, G4AON K3/100 #80