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I have recently become interested in the 902MHz or 33cms band. Equipment for this band is somewhat scarce and none is made specifically for the Amateur Radio market so the only viable route is to convert some PMR or Business Band radios.

I bought from eBay a pair of Motorola GTX900 mobile radio's which were programmed to work with a trunked radio system. The radio can support both trunked and "conventional" systems and so I was able to re-program them to work on the amateur band.

Here's a list of the stuff I used to complete the conversion;

Motorola GTX900 model number M11WGD4CB1AN (the W is the bit that denotes its 900MHz abilities)
Motorola GTX RSS software (found here on the net http://www.ham.dmz.ro/motorola/gtx.php)
A modified GTX.MDF file to tell the radio to move down to the amateur bands
Radio Interface Board (RIB) to interface the computer to the radio which I built from a kit
Old 486 DOS based PC for the RSS software to run on (it is very speed fussy - less is good!)

gtx_3.gif (32357 bytes) rib2.gif (63408 bytes)

There being no real bandplan in my area I sat down with a friend whom also wants to go this route and we worked out a set of channels for the radios.

Channel TX RX PL/DPL Description
1
2
3
4
5
6
7
8
9
10
902.0125MHz
902.6000MHz
902.5125MHz
927.5125MHz
927.5000MHz
926.1000MHz
926.3000MHz
926.5000MHz
926.7000MHz
926.9000MHz
927.8500MHz
927.2875MHz
927.5125MHz
902.5125MHz
927.5000MHz
926.1000MHz
926.3000MHz
926.5000MHz
926.7000MHz
926.9000MHz
TX114.8Hz/RX94.8Hz
D271
136.5Hz
136.5Hz
none
136.5Hz
136.5Hz
136.5Hz
136.5Hz
136.5Hz
Rockland Repeater Assn. Nyack, NY
LEARC, Queens, NY
Proposed NYC Repeater
Reverse of Proposed NYC repeater
National Simplex
Simplex
Simplex
Simplex
Simplex
Simplex

 

Some links you may find usefull;

Modified GTX.MDF file for 900MHz (RSS V1 and V2. May work on others)
Motorola's GTX Handheld sales brochure
Yahoo's AR902MHz group
GTX RSS HowTo

& Mark A Phillips, G7LTT 1995-2005
This page was last updated Sunday, January 30, 2005 08:32:45 Eastern Standard Time