michaelmuller wrote:

In our neighborhood we have a very tall hill (a short mountain, really)
that has a tower on it already. If we could broadcast from there we'd
cover the entire county.



Then you'd get the distinct pleasure of operating at further reduced
power. Height above average terrain figures into the contour
calculations that include transmitter power.

Limitations on effective radiated power are not limitations on
hardware, with flexibility in installation. Limitations of FCC defined
parameters are actually hard limits on coverage to limit interference.
And in an unusual twist on governmental behaviour, the rules attend to
results more than procedures.

So, what this means is that you cannot install a low power
transmitter and blow the output into an antenna of extraordinary gain.
Nor are you free to mount the antenna at an extraordinary height of your
own choosing above average terrain.

Put in other words: the limit is on your coverage not your
installation.