RRU 1 is West Dispatch, your signal strength depends on what site ( repeater) the dispatch goes out on. RRU 2 is used as a command channel and gets used a lot on vegetation fires. RRU 3 is East (desert dispatch).RRU 2, isnt used much, RRU 1 is used alot. I think CALFIRE uses 2 more than one.
What I have found, is West dispatch comes in clear, then the next time I can barely make out what they say. it seems to be hit and miss on clear radio and bad signal. I was wonder if I am getting reception from different towers and the scanner grabs what it gets to first.