Wednesday, December 28, 2016

Digital Mobile Radio (DMR) Part # 2

Home Brew - Kansas City Style!

Part #2

DMR is an another digital mode for hams. DMR is based on the international commercial radio standard. I could try and explain it, but the easiest way is to just have you look at: 

"The Amateur's Guide to DMR" by W2XAB

We here at BYRG World Headquarters have been experimenting in taking some of our older analog-only radios and using some behind the scenes "Sm0ke and Mirrors" secret sauce to make a very versatile DMR compatible digital radio repeaters.

The "RLP Special" chassis with a 
MCS2000 VRM-650 UHF Transmitter & Receiver decks. 

The heart of the repeater is the MMDVM Modem/Arduino DUE and the Raspberry Pi
Controller with the DMR-UTAH Pi image for software. 

We feel that this is a better way to go than the standard MMDVM Ubuntu Mate software load. 
The neat thing about this is we can also do other digital modes like System Fusion, 
D-Star & P25 as well as DMR if we want. 

Front View



Rear View

More to come on this VRM-650 DMR project as I get it completed and tested.
In Part #3 we will cover the conversion and hook-up of the MCS-2000 VRM-650 radio deck to use for the RF portion of the DMR repeater project.

This RF deck requires little overall modding 
and is pretty much a painless way to go without worrying about matching heads and cables that you might find with regular MCS-2000 radio packages. 

It just makes for a cleaner conversion and rack mounting.

All for Now - Comments Invited

SmØke out.....


  1. I am using MCS2000 radios, do you have a way to use them without a control head?

    1. I have not tried the MCS regular 2-way yet, but I don't see why it would not interface the same as the VRM series radio since they are essentially the same back end. It all goes in and out on the bottom DB-25 connector.

  2. I am told the MCS2000 does not work as a DMR repeater receiver. How is yours doing?

    1. Ours is doing fine, we are going to change the modem board out to a IMDVM modem soon, we have had good success with motorola radios working the repeater with the current MMDVM ZUM modem, but the TYT MD-380 are hit and miss.

  3. Just got my VRM-650 radios I intend to use with a DMR repeater. Also, RIB box will be here today or tomorrow.
    Can I interface to them via the front connectors?

  4. All your connections will be on the DB-25 Connector on the bottom of the radio, all front panel connections will not be used. All you will have are some blinky lights on the front that will mean mostly nothing except that your have DC power and the unit may be transmitting. The other blinking lights have no meaning.

    1. Do you mind to share the pin out connections from the mcs2000 to the mmdvm modem

  5. The reason you did not use the Ubuntu mate image, is because you did not understand all of its features. It is far superior to the Utah, with all modes incl server / mode select, C4FM, D-Star, DMR, P25, FW hex file load, dashboard and much more. You should have contacted the author.

  6. I am very interested in seeing your "Part 3" of this project, as this is very close to exactly what I have from a hardware perspective. I'm particularly interested in how you're interfacing with the 25-pin connector on the bottom of the VRM-650, as I have yet to find a DB25 connector that will fit without modification. I've considered pulling the ribbon cable from the front panel and using that to feed into the MMDVM board, but am uncertain if that will render the radio useless?

  7. Yes the ribbon cable works just fine, I have tested it. You can cut it off without a problem, I think that goes to stuff that originally was intended for the data modem.

  8. Was looking forword to part 3. Can't seem to find it. Where did you find the pinout for the 25 pin connector. We are interested in trying to make a analog repeater with them.

  9. You need to market a turn-key interface board when you get everything perfected.

  10. Have you posted part 3 of this series? I would sure like to see it. I have some MCS2000 radios that I would like to use for a DMR repeater so any help is greatly appreciated. Thanks.