I don't usually calculate alternates (because I don't find them interesting except when they are in use and then I can get it from some other site's adjacent site message), but this is what I get for 1-005:
853.1875
852.7875
I'm not actually sure why anyone would care about the frequencies with the actual audio, but for the 11 sites I can receive here are the frequencies used for audio in the last three days by site. The first number is a sense of how often it was used (kind of). Some of them with really low numbers are alternate control channel frequencies. For some sites there seems to be good agreement with what the database shows, but others less so.