Making a USB Programming Cable for old Motorolas

I've become quite a fan of old Motorola VHF and UHF radios, largely thanks to Kenneth Finnegan, aka The Life of Kenneth. He showed me that all it takes is a little software and a USB to RJ-45 adapter to program them, and you've got an inexpensive 2-meter VHF radio ready for tinkering.

Here is a quick-and-dirty how-to for making your own programming cable that works great with Motorola GM300 Maxtrac radios as well as the CDM series (750/1250).

Start with an FTDI cable/chip, these are readily available off Amazon, eBay, etc. You can see here I have a Maxton Data USB cable with the shell popped off to show the pins:

Really all we're working with here is the green wire (TX) and the black wire (Ground). The white and red wires are shorted together inside the shell — I'm guessing to bring the signal high on the Motorola radio to trigger the programming mode.

After some searching I finally came up with this wire configuration:

Pin 1	Pin 2	Pin 3	Pin 4	Pin 5	Pin 6	Pin 7	Pin 8
	Green		Black	Red	White

Grab your trusty RJ-45 Ethernet crimper and a standard RJ-45 plug, carefully line up the wires, and give it a crimp. Now plug it into the front microphone jack of your old Motorola and you are ready to program.