Finding COR (or COS) on a QYT KT8900. Some of these radios will work on GMRs and could be used to build a high power node or a small repeater. Likely have to run them on lower power with a fan. They run about $79 on amazon. No clue how reliable they are this information is to help anyone that needs it not a recommendation. I would like to compile a list of all the radios with COS points. Please submit any info you have on other radios.
Here is a link to the guy that found the COS qyt-kt8900-allstar-node
In case that link goes down here are the connections.
PTT comes from mic RJ45
3=mic
5=PPT
6=GND
Audio comes from vol control
COS comes from the main chip. Front facing you from the bottom up its the 5th pin 