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Guide for using an Out of Band Motorola CDM750 UHF radio:

There are a number of Motorola CDM-750 radios available on eBay set for UHF frequencies ABOVE the HAM band (Out of Band). Those radios have a version/part number AAM25SHC9AA1AN (there may be others, but this is the one I tested). There is some excellent information on Repeater Builder as to how to modify the CPS software in order to program these radios for "In Band (HAM)" use using CPS version R06.12.05. Considerable work to modify the CPS software was done by WA1ZYX, KA1QFA, KB1QPC, and NA5RC. I have modified the software according the their instructions and, indeed, it does work. I will summarize it here.

Software Modifications

You will also need to acquire version R06.12.05 programming software, or better know as the CPS (Customer Programming Software) and install it on your computer. There are two files requiring modification: rui41.dll and proradio.exe. You will need a hex editor for the modifications. I used HxD for the hex editor.

Using HxD, WA1ZYX modified rui41.dll as follows:

"rui41.dll" is found under "Program Files/Common Files/Motorola/RDK". Click on rui41.dll and go to "Properties" and uncheck the "read only" attribute, then save. Open rui41.dll in HxD and modify offset 0x0002720 "83 E0 01" to "83 E0 00". Save it and go back to "properties", re-check the "read only" attribute.

Using HxD, NA5RC modified proradio.exe as follows:

"proradio.exe" is found under " ". Open proradio.exe in HxD and modify:

1. offset 0x0027E450 change "75 58" to "EB 58";

2. offset 0x0027E4B0 change "75 60" to "EB 60";

3. offset 0x0027E4C0 change "75 58" to "EB 58".

Save and exit Hxd.

The last thing you will need to do is to change the "Minimum Radio Frequency (MHz)" and "Max Radio Freqyency (MHz)" to the HAM bands. This is located under "Radio Information" in the CPS. You may need to play with this a bit if your configuration doesn't work. At first, I had it set too wide.