My brother gave me a pair of Motorola 2 way radios, but im having a difficult time trying to identify what model they are, and what some of these switches do. Ive uploaded some images, this is the first one, this one works well, at least I couldnt find anything wrong with it, it dosent make funny sounds like the other one does. On this one, I want to know what the A B C switch does, and what the number knob is for, im guessing channels.