Professional Radio GP300 Series Basic Service Manual 68P64115B18C. The Motorola products described in this manual may include copyrighted Motorola computer programs stored in semiconductor memories or other media. Laws in the United States and other countries preserve for Motor. Initialize the radio using the GM300 RSS were obtained from the official Motorola GM300 Service Manual. View and Download Motorola RADIUS GM300 instruction manual GM300 Mobile Radios to the transmitter unless specifically licensed to do so by The Dealer’s Radio Service Software Manual in this manual may include.
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Programming / Service software for the Motorola Radius GM300
It has been pointed out to me that this software only works with the GM300 so I have adjusted the page.
After searching for the genuine Motorola program I came across Motorola Radius GM300 Radio Doctor. This program runs fine under Windows XP and will do all the functions that the genuine Motorola radio service software does. Here is the main screen.
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See a video of the software in use
If you want a copy of Motorola Doctor software just join the following group
You will also need a simple interface to connect the radio to your PC. You can make your own or just search on Ebay for 'GM300 programming' or make programming interface from below 'at your own risk'
GM300 programming connection When looking at the radio here are the numbers
As you can see to make the programming interface for your GM300 is very basic.
Connection your Motorola GM300 for Echolink or IRLP etc.
If you want to use the COS/COR output from your GM300 the COS/COR on pin 8 is (active low). Many interfaces need a COS/COR input that is (active high) at 2 to 5vdc. You can make up a circuit to convert the output from pin 8 or take a COS/COR output from inside the radio that will give you a (active high) output. You will need to access the logic board on the underside of the radio. Remove the front of radio and the bottom cover and lift off the RF shield. See photo below.
If you use thin wire you will be able to feed this out the edge of the 16 way connector. I tied a knot round the connector on the board to stop it being pulled off the board. Take care not to short this COS/COR out because it will damage the radio.
Attention Ebay buyers and sellers: If you are buying or selling a MaxTrac, Radius mobile, or GM300 you need to read the warning on this page.
Any Motorola prices mentioned on this page (or on any page at this web site) should be taken only as a rough guideline. Motorola adjusts prices quarterly, and offers one set of prices to their dealers/service shops (the so called 'NSO' Pricing ('National Service Organization')), another to 'self-maintaining' fleet customers (i.e. those that have their own radio shops... cities, counties, police departments, fire departments, etc) and a third on their telephone order desk (i.e. retail sales to the public). Prices are changed quarterly, so use the mentioned prices only as a rough indication. If you encounter a large price change on anything where we've mentioned a price we'd appreciate an emailed update.
Radio Modification and Descriptive Articles:
Caution: A lot of the information in the articles below is valid only for MaxTracs and MaxTrac-based Radius radios (the Radius mobiles that have the letters LRA in the middle of the model number). The MaxTracs came first, then when Motorola needed radios to sell as Radius models (i.e. retail sales products) they changed the label and the firmware. There are some very slight differences, but there is a lot of commonality between the hardware (the circuit boards, etc) inside the MaxTrac and Radius LRA series mobiles.
The later GM300 series (which includes the Radius M10, M120 and M130 radios) look a lot like the MaxTrac and Radius LRA series, have similar specifications and physical construction, but are actually quite different internally. The GM300 series do not respond well to being blanked by the MaxTrac Lab RSS. There is no Radius or GM300 series Lab RSS floating around (yet) so unsuspecting experimenters can turn one of these radios into an expensive brick if not careful. See the GM300 article below for more details.
Astron makes a power supply for the MaxTrac / Radius LRA / GM300 series that has a sleeve on the top that the radio slides into. The SL-11-RRA supplies 13.8V at 11 amps. Click here for a photo.
Note that the MaxTrac / Radius / GM300 radios have a 10% transmit duty cycle and that translates to 10 seconds of transmit and 90 seconds of receive, or 30 seconds of transmit and 4.5 minutes of receive. This is definitely not repeater service or any kind of amateur radio service that I'm familiar with! And besides, the rear mounted heat sink does not cool the pin diodes or any other PC-board mounted components. Reducing the transmit power can help, but some models have a minimum rated power level (like not less than 25 watts and not more than 45 watts). In other words, the MaxTrac, Radius and GM300 are nowhere near the conservatively rated and over-heat-sinked designs of the MICOR, Syntor or Mitrek era radios.
Model-Specific Articles:
Some additional GM300 information is available from Colin Lowe G1IVG at http://www.g1ivg.com/motgm300.htm (offsite link).
Interfacing Articles:
Modification and Repair Articles:
Manuals and Documentation: If anybody wants to contribute additional part numbers (or even manual scans) we will post them.
Parts Catalogs:
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This page originally posted 05-Jan-2005
Credits and Acknowledgements:
MaxTrac, Radius, GM300, Spectra, GT, GTX, GR300, GR400, GR500, Hear Clear, Radio Service Software, RSS and many other names are trademarks of Motorola Inc. Front-view photos of the two-channel and multi-channel radios at the top of the pageby Robert Meister WA1MIK. Edited text, artistic layout, and the hand-coded HTML is ©Copyright 2005 and date of last update by Mike Morris WA6ILQ.
This web page, this web site, the information presented in and on its pages and in these modifications and conversions is © Copyrighted 1995 and (date of last update) by Kevin Custer W3KKC and multiple originating authors. All Rights Reserved, including that of paper and web publication elsewhere.
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