So to give a quick back story, I picked up a pair of M1225 (4 channel, 25w) units on ebay. Physically, they seem in great shape. TX/RX work on each (the internal speaker on one is a little wonky, but frankly I don't care for my use case). I have no problems writing a code plug to the unit (although, that initial setup was indeed fun!). I am trying to build these units to operate as a GMRS repeater (they are type 95A certified, I prefer to keep everything 100% legal).
The issue I am having is with the COS output. My understanding is that, for this to work, I need to configure Pin 8 as "PL/DPL - CSQ Detect" with output active low. I have things configured this way, but I can NOT get the RX radio to key up the TX radio. For kicks, I have also tried using Pin 4 (since it can be configured for the same PL/DPL - CSQ detect mode) and it doesn't work either. Even trying it with just "CSQ Detect", neither pin goes low when the radio receives. I have also tested this both without a mic connected, and with a mic connected that is "hung up" on the clip.
While squelched, pin 8 has 4.6v. While receiving (indicated by the channel number blinking AND being able to hear audio from the speaker), the voltage stays the same. The output on pin 8 does NOT go low.
I hope someone has some ideas, because I am at a complete loss.
Thanks in advance for any suggestions!
EDIT: I just went back and double checked. The two radios are behaving differently. One radio (lets call it radio A) shows 4.6v on Pin8 while squelched, the other (radio B ) shows 13.8 (the power supply voltage). They both show 4.6v on Pin4 (when configured for PL/DPL - CSQ Detect) at all times, whether squelched or not. Not sure why the two radios would behave differently.
EDIT2: In case this is relevant, I was told these radios were both pulled out of a working SCADA system.
Edited by Steve (WRDR 762), 29 October 2020 - 08:56 AM.