N0RQ's notes on the GE MVS radios

There is a nice handful of fellow hams who use the GE MVS radios for amateur use, both voice and data.  Three or four of them have been particularly helpful to me in understanding how they work, and without mentioning names/callsigns, a big thank you to each of them.

In an effort to assist others who might be interested in doing the same, this web page has been put together.  First, some links:

eHam.net review of GE MVS
VE3FYN notes (very helpful)
KD4BBM notes (includes several alternative ways of modifying these radios)

The MVS units are particularly suited to data/packet use, mainly APRS, but also Winlink and traditional packet.  Some guys even use them as simplex IRLP nodes.

Programming the MVS requires software (old DOS software available on the internet in a Yahoo Group called "GE", files section, folder called Programming software, look for the file called MVS v 3.zip), as well as an interface.  Sometimes, those interfaces can be found on eBay for ~$50, but the only place I know of right now is here:
http://www.priceindustries.com/mvs.html (MVS-2), though $75 seems just a bit pricey.

Since it is not easily programmable, it is not nearly as frequency-agile as a typical 2m ham radio, thus using it for voice is OK, as long as you don't ever need to change to a freq that isn't programmed into the unit.  But this is where this model shines for data -- it can be programmed for all the normal data/packet freqs, still have some channels left over, and you shouldn't ever have to worry about having to reprogram it.

Most of the MVS models have 16 channels.  Some have only 2, and a very few have 128.  With the 2-channel model, you can program one for 144.390 and the other for the "backup" APRS freq of 144.340, or whatever else you see fit.  I use a 2-channel model in my car as an APRS tracker.  Works great, costs a bunch less that most any ham radio.  My other MVS units (and the ones I sometimes sell on eBay) are all 16-channel units.  By default, I program in 5 packet freqs and 4 APRS freqs, leaving 7 open spots, which can be filled with NOAA WX freqs, repeaters, simplex, etc.  You can see my MVS setup for Winlink if you're curious.

Here are some files that might be of interest:
MVS model #s & descriptions (.txt)
"Maint" manual (.pdf)
Operators manual (.pdf)
Installation manual (.pdf)
Service section manual (.pdf)
schematic of the data / accessory cable (.jpg)

More MVS manuals and other GE manuals can be found at Repeater Builder web site.

How I convert these things to amateur/packet use:

  1. power up test, see if all buttons work (some buttons tend to get dirty/sticky after many years)

  2. program with my list of default freqs (7 NOAA WX & 9 packet/Winlink/APRS)

  3. check power output and frequency accuracy

  4. remove from power!, then remove bottom cover, and:
    a) plug in orange speaker wires/plug if it was unplugged
    b) remove extraneous post-manufacture tone board, if installed, insulating ends of wires
    c) cut one orange speaker wire, install external switch, so speaker can be turned off (because the Volume control on these radios will not go down to zero, and no one wants to listen to packet sounds for very long)

  5. reinstall bottom cover

  6. cut off original power connector and data cable plug

  7. strip power & data cable wires

  8. power cable: orange and red twist together, attach to fuse holder, then attach red/black zip cord to negative lead & fuse holder

  9. data cable: attached DB-9M cable wires to MVS data cable wires (standard of 4 are needed, + 1 if providing power from the radio to a TinyTrak or TNC)

  10. install TNC-male to UHF-female (SO-239) adapter

  11. test: 1 minute xmit stress test, watching power & freq stability;  also test with TNC or TinyTrak for functionality

  12. final cleaning, checking, & get ready to sell


This picture shows an MVS powering a TinyTrak3 via tan DB9M cable (black GPS cable shown on other end of the TT3).

A few items of note:

 

Microphones -- if you have a mic for one of these radios, great, they work fine for repeater/simplex voice use.  There is a trick, though, related to mics and PL/CTCSS tones in receive mode.  The GE mics came with a special mic holder that had a magnet on it, and the mics themselves have a reed switch in the back of the mic.  When the mic is hanging on the mic hook ("on hook") the receive PL/CTCSS programming is honored.  However, when the mic is "off hook", any PL/CTCSS requirements for receive are ignored.  So if you have a mic plugged in, and you're hearing stuff (on a repeater freq mainly) that should be ignored because of PL/CTCSS, it is because your mic is "off hook".  The special mic hooks are rather hard to find, so to force the mic to stop the on/off-hook silliness, open up the back of the mic and clip the little (blue?) wire that goes to the little switch area at the back of the mic.  It will make the radio think that the mic is always on-hook.  End of problem -- the radio will now always honor the PL/CTCSS tones on receive.

 

More stuff coming later...

 

 

73, Dave, N0RQ

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