Quote:
Originally Posted by nukeman
Is there a good way to know if this will all work before I purchase the equipment? Are the equations good enough?
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You're right, the 9 db is an average of the two VHF stations. Reliable reception of these two stations should be easy. The UHF stations are iffy.
The preamp is needed to overcome the line loss of the leadin wire from the antenna, remove mismatch losses from the equation, and to overcome the unpredictable and higher noise figure of your TV set.
The propagation equations are statisical approximations. In addition to the uncertainty of statistics, there are variables such as transmitter antenna patterns that cannot be accounted for precisely. I like to see a net NM of +10 db before I'm comfortable. Even then there will be days when the weather will interfere with the signal.
A tower will help if gets you over the tops of nearby trees or rooftops. Otherwise, the location of the tower could built be in a cold spot as easily as a hot spot for reception. Walking the roof should get you as much extra signal as a 50' tower.
If you want a "plan B" for UHF reception consider this,
http://www.hdtvprimer.com/ANTENNAS/16bay.html but using two 91XG antennas.