If you put up a "70 foot stick of Rohn 25" Greg, why dont you just build
either an L-network with a coil and a capacitor, or for better bandwidth a
T-network with a combination of coils and capacitors to match the tower to your
transmitter? At the very least you are going to need a capacitor rather than
an
inductor at the base of the insulated tower to wash out the reactance. A
vertical antenna of a quarter wavelength in length (which is where you are
close to
here) will be somewhere in the neighborhood of 50 ohms resistive and have 70
ohms or so of capacitive reactance. Just make sure that you have the ground
system completely installed before you match the thing as the match will change
somewhat when you add radials to the system.
I have something along this line here for my 160 antenna although it is a bit
longer than a quarter-wave and is top loaded with my 20 and 40 meter stacks.
I just built a T-network to match the antenna for 160 and it works great and
has pretty good bandwidth.
73...........de Goose, W8AV
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