The Phillips FM320 UHF CB has the facility to be locked to a particular channel. This is controlled by the existence or absence of a number of diodes on the circuit board. I’ve been looking into this for a telecommand project I’m working on. I wasn’t able to find the information of how to do this anywhere else, but it was pretty straight forward to figure out.
This post describes how modify the FM320 radio to set the nominated “NOM” channel.
Here’s a blast from my radio past, the Phillips FM320 UHF CB radio. I’ve dusted one off from the slowly collapsing box of radios left over from my farming days. My plan is to use one as the receiver for my DTMF pump switch.
As a kid I had always been encouraging Dad to consider radios for the farm. I was a regular reader of CB Action and it seemed like the perfect excuse. He never succumbed to this until the advent of UHF CB. We had seen them at one of the field days, and organised for a Phillips representative (a German guy called Hans) to come out to the farm and do a demonstration. Hans arrived with a wind up mast that he set up at the house and wound up to the same height as our TV antenna. Then we drove around the farm to see what the coverage was.