About 20 years ago, I met some guys in the Dallas area who were using modified commercial Motorola radios on 2m and 70cm. I never saw a dual-band radio but the radios they had were pretty nice. Tough as nails, too. They were a bit pricy and I was happy with my Icom HT and mobile radio so I chalked it up to learning something new about ham radio.
Fast-forward a few years and I decided I wanted to get on 900 MHz. I don’t remember why, but I’m glad I did. I bought a Motorola Spectra from a guy who sent it pre-programmed and ready to go for most all areas in the US that have 900 MHz repeaters. It was a 15 watt model and worked great in my car. I wanted something for the house so I got a 30 wall Spectra from the same seller. Several years later I got a MTX-9250 HT and a Motortrbo XPR 4380 (last week).
When I first got the Spectras, of course I wanted to monkey around with the programming. You can’t just program these from the front panel like you can with radios sold in the amateur market. You plug these into a computer and use Motorola’s proprietary CPS software. The software has a learning curve but once I got the hang of it, I was able to program all of my radios whenever changes needed to be made.
The downside is two-fold. With the Spectras, you need to use a very old computer, and by today’s standards, downright ancient hardware is REQUIRED. I’m talking about a 386 and maybe a 486 if the speed is 66 MHz or less. This is because the older hardware uses slightly different UART signalling on the serial port and the radio will not talk to the computer if the signalling isn’t just right. There are some hacks out there such as “slomo” that will emulate a proper serial port. I’m reading into it now but I’ve always been a little paranoid to try to program my radio with anything but the real McCoy. And besides, CPS needs Windows and I’m a Linux user so I have to run it in a virtual machine. It works for programming newer Motorolas but not the old ones. Unfortunately, my old machines have all died so I’m currently on the hunt for a “new” dinosaur computer.
The second downside that makes working with Motorola radios the most difficult is the programming software. Once the proper mods are made to the radio (not all models will require hardware mods), then you get to worry about the software playing ball. CPS is not open source and unless you know someone with a copy, you’ll need to register with Motorola to download it. Thankfully, the software is free but a pain in the ass to get. Once you have the software in hand, will it program your radio? The software is made with commercial radios in mind so not all of them will include the amateur bands out-of-the-box, even after making hardware mods. If the CPS doesn’t let you enter amateur frequencies, you have two choices: 1. modify the codeplug in memory as you use CPS or 2. hack the CPS itself. There may be another method but I’m new at this and these are the ones I’m familiar with. Perhaps one can hack the codeplug file itself, I don’t know yet.
I’ve tried changing CPS values in memory but haven’t had much success yet. Hacking the CPS is a whole ‘nother story. You have to know what you’re looking for, how to change it, and then find something else you can change in order to satisfy a checksum. Lots of fun! Both methods require the use of a hex editor. Figuring out what to change seems to be very model-specific, just as the software is. From what I can tell so far, some CPS versions are easier to hack than others. There is a lot of documentation on the internet that I won’t repeat here but this part is the most challenging.
From what I understand, the newer Motorola models don’t require as much modification in most cases. My MTX-9250 required none. Just be careful about which model Motorola you buy. For example, the XPR-4350 is offered in a VHF version as well as two different UHF versions so make sure you get the right one if you want coverage on 440-450.
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