It works . . . I think

After programming the Motorola GM300 VHF radio yesterday, I built a simple interface cable to be able to connect up a non-Motorola microphone and a PTT button.  For that, I used a headset I had lying around and a big button designed to be used on a commercial video game.  I also took the time to add a Dean's power connector to the pigtail I was using for the radio so I could connect it up to the power supply the right way.  For the antenna, I picked up a mini-uhf to so-239 adapter at Radio-Shack and hooked up my usual 3 element yagi.

I was able to key the repeater, but the operator I talked with said my audio was low.  And that's entirely possible.  Motorola uses a pre-amplified microphone, so there may not have been enough output from the setup I was using.

So I'd say that this purchase was a qualified success.  Qualified in that there will need to be more testing done to see if the radio is able to actually perform the functions I have in mind for it.  Function one is as a digital coms radio.  Both APRS and digital packet.  APRS will require that I get a TNC, but general packet I can do with a simple homebrew interface and a computer.  My junkbox has expanded enough that I should be able to bolt together the interface, and I have a spare quad core AMD computer around that I can use as the host system.  Function 2 would be an Echolink radio.  Again, I need the interface and computer.  But I think I can use the same interface and computer for general digital and Echolink.  The last function would be as a repeater system when combined with another radio.  This fits in with my original overall project for this year. 

Having worked with Motorola radios for years in law enforcement, I've come to view them as sturdy and well built.  Pretty much able to take any punishment dished out to them.  After some continued research on the net, I find that this isn't the case for the GM300.  It's very much a consumer level device, meaning it's the standard 5-5-90 duty cycle.  I'm hoping that by adding a temerature controlled fan or fans on the heatsink for the PA deck, that I can "adjust" the duty cycle into something a little more useable.

Time for work.  Have a wonderful day!

73
Steve
KDØWSW