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
  http://www.repeater-builder.com/products/stm32-dvm.html
• 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.

• Chicago Electronics Distributors
• Adafruit
• Micro Center (best picked-up at local store)
• Vilros
• Cana Kit

… more information to come :)