what do the rf gain and mic gain buttons do on a 2 way radio?

Answer 1

Not sure what this has to do with car audio...

RF = Radio Frequency, so it adjusts the gain (roughly explained as a volume control, very roughly).

The same for MIC gain, it adjusts the sensitivity.

Answer 2

As you describe it, the radio might be either a Citizen Band Radio, PMR Radio or Amateur Radio. The answer you have already explains the rf gain and mic gain correctly but as a legal Radio Amateur I advise you to consult the appropriate body as you will probably require a licence to operate the radio, or risk of prosecution in some cases might ensue. OFCOM are responsible for the regulation and control of all transmitting equipment other than the 'kiddy' sets used for very short distance communication.

Answer 3

RF gain will make the receiver more sensitive as it is turned-up allowing more distant signals to be received, and Mic Gain increases the sensitivity of the mic so that your transmission is louder to the receiver.