Moto GR300 upgrade?

[Stripes]

So I have a Motorola GR300 that uses duel radius gm300 radios with a Rick. However I can not for the life of me get the RSS or even a XP cps to work with it. Therefore I want to replace the gm300's with something that will still work with the Rick. What should I look into getting?

[WRAM370]

If you are looking for a Motorola radio that will easily plug into the 16 pin connectors of the RICK, and can be programmed via CPS rather than RSS, the CDM series or CM series would probably work for you and not cost too much. But you will have to source the CPS for those radios. Sometimes you may find in in an internet search, or you may find it through a Motorola dealer that is “ham-friendly”, or in the case of this forum, GMRS-friendly.

Be aware that some of the later Motorola radios are narrow band out of the box, to meet FCC regulations regarding commercial service, and may require an entitlement ID or “key” to add the wide band menu option to the CPS. This is dependent on the CPS version your radios are programmed with, and is generally not backwards compatible with Motorola models.

You may have seen videos where DOSBox is used to program GM300 radios with modern computers, and the videos show success. I have had not such luck using DOSBox on my GM300 radios, but I have a Zenith desktop from 1995 running DOS 6.2 and Windows 3.1, so I didn’t try too hard to get DOSBox working. The communications port speeds are the real issue when trying to program via old RS-232 comms ports.

[Radioguy7268]

CDM's can work - but there's a learning curve with the CDM models. You also need to be real cautious with buying those off Ebay - as there are a ton of CDM radios that have been hacked and cracked. Things like LS+ trunking models that have been flashed over to conventional.... or LS models that only do 16 channels in conventional mode, and can't do MDC.

Personally - I'd tinker around with DOSBox for a GM300. The trick that worked for me was setting the "CPU Emulation" to act like a 386. The rest seemed pretty much standard. I have been able to program anything from Radius M300, M120's, SM50's or GM300's.

[Stripes]

From you guy's suggestion, I went ahead and looked into a CDM750 and a CDM1250 and I think duel 1250's will work perfectly fine for me. I noticed that they have additional pins but if im not mistaken, the outer 2 on each side can be disregarded and it should be plug-n-play. Ill have to compare the pinouts from the GM300 to the CDM1250 to make sure I dont fry anything, and just to be safe in knowing what im doing. 

 

I have tried working with DOSBox on the GM300 but with everything I've tried, I got no luck. I tried it on Windows 7 and Windows XP, changing the serial port settings, trying different cables, and on and on. I really have exhausted my options with it and if I do get it working, learning how to program it will be foreign to me completely. Im sure ill miss some settings that might be a no no. Thats why im wanting a more modern CPS to tinker with and I have successfully gotten my hands on the Professional Series CPS for the CDM. Thank you for the heads up on the eBay listings. I know there can be some bad eggs on there. I usually go to my state surplus first to see if they have anything and that's how I got the GR300 to begin with. They do a good job wiping and removing any passwords on radios when ever they do appear.

[Radioguy7268]

You are correct about the outer pins - they can be pretty much ignored, and the center 16 pins will follow the standard Moto conventions of Radius mobiles. Be aware that the CDM radios will not fit in the stock GR300 housing - the control heads are too big. I've seen people just screw in a mobile mount at the top of the GR300 housing for a cludged look.

Also, you really should wire in ignition sense for the CDM mobiles - as they will not automatically restart with loss/restoration of power otherwise. Not a big deal if the repeater is on your desk, but a PITA if the repeater is at a remote tower site.

One final consideration for the GM300's - consider finding yourself an old-timer "Elmer" who might already have all the cables/software/knowledge for programming the GR300. Even if you pay him $50 for the trouble or buy him lunch, it's still cheaper than buying a set of used CDM's.  Most commercial shops won't touch a 25+ year old repeater for anything other than a trade-in, but the guys who work there probably have the tools and knowledge to do the job if you get on their good side.