ad: 100watts-1
Results 1 to 3 of 3

Thread: How to build Motorola GM300 repeater controller?

  1. #1


    I have 2 Motorola GM-300 UHF mobile sets extra and I would like to make it as private homebase repeater. I'm looking for simple controller interface schematic diagram for these RIGs. Hope to get the info for this, thank you very much.

    Kota Kinabalu, Sabah, Malaysia

  2. #2
    Join Date
    Feb 2003
    **** Rest in peace sweet Caylee *****


    Here is a very simple circuit that will get you going. It has no timer or "control" per se, it is just an interface to key the transmitter and get audio from the receiver to the transmitter.

    Here is the discussion about that circuit on the Batlabs site - one dedicated to Motorola equipment.

    Please keep in mind you will need to dramatically reduce the power output on the GM300 transmitter. That radio was designed with land mobile style transmissions - a few seconds at a time. It will overheat quickly transmitting for longer than a minute or so and will need a LOT of extra cooling in addition to reduced power.

    Good luck, I fear though you will be disappointed using the GM300s long term.

  3. #3


    Thank you for your infomation. I will try on this.

    How about if I also want to transmit on VHF 2M, I have 2 sets of Yaesu FT-1500M as well, do you have any idea about this repeater interface with timer delay? I look forward to receive your reply soon, best regards.


    Kota Kinabalu, Sabah, Malaysia

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts