Motorola GTX
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The Motorola GTX name, confusingly, refers to both a portable and mobile radio, with models for 800 or 900 MHz.
They don't natively support operation in the 900 MHz ham band, but a modification to the programming software seems to be all that is required to achieve good operation there.
Caveat Emptor
There appear to be a lot of hams using the GTX on 900 MHz, including myself (with some help on the programming). There are some things you need to be aware of, though:
- Programming is a bear:
- The radios can be programmed only with Motorola's proprietary RSS. If is unclear to me if it is even sold anymore.
- You will need a RIB (Radio Interface Box) to go between your computer and the radio for programming.
- GTX RSS runs in DOS! RSS of this vintage tended to use timing loops (!) in software to avoid writing to the radio too fast; running on a remotely-modern computer may fail to work.
- The software needs to be hex-edited to program for the ham bands.
- (Mobiles) Although these have an internal speaker, you'll need to rig something up on accessory port to get the radio to actually use it. (Some radios apparently also require another connection on the accessory port for ignition sense, or the radio won't turn on.)
- (Mobiles) Most of these only put out 10-12 Watts.
- These are all (?) trunking radios that happen to do conventional. There are some weird quirks, like requiring having a dummy trunked channel, in order to use it.
- Only a limited number of channels is supported—between 4 and 10, depending on the radio.
In short -- these can make very solid, reliable radios, but it goes _much_ easier if you know someone who can help you get started.
Resources
I'm still new to this. Here are some resources I found along the way:
- N1SU's 900 MHz page is an excellent overview
- N1OTY's MMRA presentation (PDF) is also a great overview
- Repeater Builder, as always, has a wealth of information. Their GTX index is a great starting point, and has a bunch of linked pages with further details, including whole pages on the portable and mobile variants.
- KC7GR's GTX page specifically addresses how to hex-edit RSS to allow programming in the ham bands, and permitting more (but still few) channels.