Week 11 – DMR Deviation & Case

I enabled DMR last week and spent some time configuring it. This week I had to set the DMR transmit deviation in order to get it to work.

Essentially setting the TX deviation for DMR is the same as how I set the transmit deviation for DSTAR in the beginning. I used a service monitor and checked the deviation level while the repeater was transmitting. It was lower than it should have been, so I increased the level in the expert MMDVMHost editor on the line that said DMR Level. This adjusted the deviation for just DMR, leaving the deviation alone for all other modes.

I also created a box/case for my project out of a large crayon box that I found at WalMart for about $3.

  1. I used a template for the Pi to drill four holes in this box for some #4 screws to mount the Pi and MMDVM duplex. I also put a piece of acrylic between the Pi and this case so that it wouldn’t be pressing against the back of the Pi.
  2. I then cut out a hole for the size of my 3.2in Nextion Display.
  3. I also drilled holes around the display cutout to mount the display in place.
  4. I used plastic from an old ice cream container to create a bezel to go around the display since part of the display doesn’t show anything and is instead used for the touch screen controller/wiring.
  5. I added two external antenna connectors. I bought two male to female jack/panel mount SMA connector extensions for about $6 each and then I added some right angle SMA connectors (male to female) 5 for about $4.
  6. For the external antennas I drilled the holes in the box as far apart as I could and installed the female jack connectors through the hole.
  7. Then I screwed a right angle SMA connector on each jack.
  8. Next, I used a couple right angle SMA connectors on the MMDVM hotspot/repeater board.
  9. Finally, I installed all of the electronics.Here is the finished case.

Author: Tyler Morris

I am a senior computer information systems and technology student at the University of Pittsburgh at Bradford. I am currently pursuing a B.S. in CIST with a minor in Digital Graphic Design. My focus is on computer repair and web design. After completing my undergraduate degree in CIST, my plan is to attend graduate school for a masters in social work.

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