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GE index Back to Home | Programming the Maxon SM-4150M or the GE Monogram Mobile Radios By Scott Lichtsinn KBØNLY Turned into an article by Robert W. Meister WA1MIK |
I recently ended up with some Maxon SM-4150M mobile radios that I wanted to program. After searching online I only found tidbits of information available on these.
Turns out they are the same as the GE Monogram series. I had assumed GE produced them for Maxon and then rebranded them as their own; it's the other way around: Maxon made them for both companies; GE just put their label on them. They can be programmed with a suitable serial programming cable; the receptacle is inside the radio so you must remove the top cover to plug it in. The schematic of this cable is available online and with some time and effort and money it could be duplicated. There is also a schematic of the SM-4000 programming interface available online as well, so feel free to build one if you prefer, but that will also require purchasing the correct connector to mate with the socket on the circuit board as well as some other components for level conversion. For me, it's always better to be free or cheap, so I found an alternative: since the radio must be opened anyway, just remove the serial EEPROM and reprogram it directly.
The photo below shows the location of the serial EEPROM and the programming connector, next to the microprocessor:
Things You'll Need:
You will need the SM-4000 programming software. It's an OLD DOS-based program but I did find it worked fine on my Win2k-based workbench computer. This software is available from various online web sites, one being www.mods.dk under 'Misc' in the 'Other' category.
You also need a hex-editor program (I use Hex Workshop by BPSoft) to edit the file generated by the SM-4000 program, and a serial EEPROM programmer capable of dealing with the 93C56 Serial EEPROM memory chip used in the radio. I used an inexpensive Willem-style programmer.
Comparing The Data:
I determined the frequencies that were in the radio by using a frequency counter next to the radio (with a dummy load attached) to detect them. Using the programming software, I created a file that had the same frequencies as the radio. I removed the EEPROM from the radio and read it with my EEPROM software, saving that data to a disk file. I was then able to compare the EEPROM data to the file I created with the software; this allowed me to find the starting and ending locations of the data that I needed to copy from the file the program generated. The program creates a file with more info than is needed for the chip; I presume this information is sent to the programming interface for some purpose.
The contents of the radio's EEPROM file, all 256 bytes of it, viewed using Hex Workshop, are shown below.
I then viewed the file generated by the SM-4000 program with Hex Workshop. (This software saves its output as a .CHN file but it is still a hex-format file.) I've put a line through the extra data contained in this file indicating I'm deleting all bytes before hex address 5E and all bytes after hex address 15F. Only the 256 bytes from hex address 5F through hex address 15E (inclusive) should remain.
After deleting all of the crossed out information and saving the file with Hex Workshop to a .BIN file for my EPROM burner software, I was able to burn the data to the EEPROM. After reinstalling it, the radio still functioned!
Summary:
So here's the process: use the SM-4000 software to create a new file with all the frequencies that you want the radio to have, save it, open it with Hex Workshop, delete the crossed out portion of the data, save that to a .BIN file, and burn that data the EEPROM. Success!
You will know right away when you turn the radio on if it's programmed correctly; if you hear the rising tones when you power the radio on, it has passed its self-checks. If you get no rising tones it will display 'Er 01' on the display for an EEPROM error. I found no problems getting it to lock on frequency between 144-174 MHz, even though the rated split is 148-165 MHz. I haven't been able to locate a service manual and I don't know what there is for VCO or front-end adjustments on these units. I haven't looked in the service manual (LBI-38864B) but I can say from testing that it works fine as-is in the ham band. It's possible though that because mine were programmed at the bottom of their range that the tuning is close enough; if yours has programming at the upper end of the radios range, adjustments may be necessary.
Contact Information:
The author can be contacted at: kb0nly [ at ] mchsi [ dot ] com.
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This page originally posted on Wednesday 21-Jul-2010.
Article text and photo © Copyright 2010 by Scott Lichtsinn KBØNLY.
HTML conversion © Copyright 2010 by Robert W. Meister WA1MIK.
HTML conversion © Copyright 2010 by Robert W. Meister WA1MIK.
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 RightsReserved, including that of paper and web publication elsewhere.
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