Adventures at the speed of light™

Motorola CDM1250 HomeDigital Repeater

It's been a while since I documented any of my projects and my how time passes when you are busy, for that I apologize. Anyway, thought that I would document the project to help other HAMs looking for information in regards to doing this project. I know I have had to scrape info from all sources dating back to 2017 :D So, here it is—enjoy!

The plan

Saturday - October 2, 2021

Basically, I am going to repurpose these mobile radios to become a multimode-capable repeater.

Here are the parts to source and the software. Program the radios and put it all together. Here are the parts I needed to make this.
  • 2 x Motorola CDM1550LS (VHF)
    from eBay, other markets places or Ham friends :D
  • Motorola Low-Profile Mounting Brackets from eBay, etc…
  • STM32 MMDVM Pi-Hat
  • Raspberry Pi 3B+
    (a 3B would do as well, but the extra horsepower is welcome)
  • Raspberry Pi 3B Case
  • 19U Rackmount Server or Repeater Case
    (I got a server case for $25 + tax from Excess Solution)
  • 12v 30A Power Supply
  • 12v to 5v Power Converter
  • DB9 Male
  • 2 x Motorola 16pin Accessory Connector (HLN9457A)
  • Interface cables (I use CAT6E or CAT5E)
  • Thermal control switch
  • 3 Pin Power On-Off Switch
  • 14 Guage Power Cables with in-line fuses
  • 18 Guage Cables with in-line fuses
  • 2 x 80mm 2-wire fan

A piece of that Raspberry Pi :D

Saturday - October 2, 2021

So far I have ordered the parts and have not really run into any issues except for the Raspberry Pi 3B+ which seems to be out of stock from the stores online—because of the shortage we have due to the pandemic. Here are a few of the stores in the USA to get them from, they might be OOS (out of stock) so get in the wait list or notification list if you can.

… more information to come :)