Jim,
So, are you saying that range is unlimited at UHF as
long as it's 'line of sight'?
Assuming that the transmitter's output for both radios
are the same, and both receiver's sensitivity is the same,
and both have a usable range of 3 miles. That means for
the two stations to hear each other they have to be within
three miles of each other. At 6 miles neither will be able
to hear the other because they would both be out of each
other's usable range. Wouldn't matter what the 'line of
sight' distance was. Propagation will make a difference,
but we're talking about the 'normal', every day state of
propagation.
'Doc