The GM300 uses a proprietary Motorola DB25 (25-pin) connector on the back of the radio. To connect to a modern PC, you need a RIB (Radio Interface Box) or a RIB-less programming cable.

Once you have the software running on Windows 10, here is the typical workflow:

Vital Note: The GM300 does not support out-of-band frequency ranges without hardware modification. Trying to program a VHF GM300 (146-174 MHz) to 2-meter HAM band (144-148 MHz) usually works, but forcing UHF (403-470 MHz) to 440 MHz HAM band requires a frequency adjustment tool—not just software.


The GM300 uses a proprietary connector. There are two types of cables available: