Hi Doc, as I remember (and things could have changed), 20 and 56 don't have backup antennas. Don't remember about 62, but they probably do. Anyway, back in the day when 56's analog transmission line died, they were only allowed by the tower owner to work at the top at night to not take the other stations down during peak hours. I am not sure what is different now, except maybe that many of the channels have a fiber line to some cable companies and they view that as enough coverage. But as you know, not everyone gets their channels that way.