Motorola’s Radius GP and GM series radios are now cancelled. But there were so many of these radios sold that there are still many around and still in use today! That’s why we’ve put together this guide to programming the Motorola Radius GP300 series two way radios.

NOTE: This guide does not tell you how to program the Radius GP300 and GM300 series radios. It outlines what you need to program them. If you would like to learn how to program these radios, we will link to a few guides at the bottom of this page. You might want to join this dedicated group on Facebook.

Portable radios covered by this guide:

  • GP300
  • P110
  • GP350
  • GP280
  • GP88

Mobile (vehicle) radios covered by this guide:

  • GM300
  • GM350

Programming Cables

It probably goes without saying that the portable radios and the mobile radios in the Radius GM/GP series have different programming cables. The portable radio is programmed via the back of the radio. Whereas the mobile (vehicle) are programmed using a cable that plugs into the front of the radio*.

* There is a method of programming the GM300 and GM350 radios from a connector on the back. We do not cover that method in this guide as there is not enough information about it.

Prerequisite: USB to Serial Cable

No matter what radio or cable you will need to use, if you do not have a COM port directly on your PC or laptop, you will need a USB to Serial cable. It is important that you buy an FTDI chipset USB to serial cable.

Buy from Radiotronics UK:

Portable Radio Programming Cable

Radios covered: GP300, P110, GP350, GP280 & GP88

The portable radios in this series are programmed using a cable that connects to the back of the radio. Because the programming kit replaces the battery, you will also need a 9v supply. Unfortunately, the original cable is long since discontinued by Motorola. But there are some aftermarket replacement cables.

Note: The GP300 and GP350 have a different battery profile and therefore require different cables.

Motorola GP300 Radius Programming Cable

You can buy these cables from our friends at RadioArena here:

Mobile (Vehicle) Programming Cable

Radios covered: GM300 & GM350

If you have either the GM300 or GM350, you will be able to find a cable at Radio Arena here.

Programming Software

Batlabs has, by far, the most comprehensive list of programming software versions for these series radios. You can see the home page (or their mirror site at Angelfire).

You can download the Radius GP300 software from Radiotronics UK free of charge. However, it must be noted that we can’t give you any help programming.

The software only runs on MS DOS, not Windows.

Further Help

Please do not contact Radiotronics UK about programming this radio. Instead, you can find help in the following places:

The software only runs on MS DOS, not Windows. Here are some solutions online including a solution by G1IGVa solution by KK6JYT and a solution using DosBox.