I use 3 "vertical slopers" around the tower. I believe it was
originally written up by K8UR, and is in the ARRL Antenna Handbook
(mine's about 10 years old, don't know if it's still there) as a 40m
antenna, using 5 slopers.
Start at the top of the tower with one end, then the lower end is
pulled back in to the tower, so the center insulator is half way up,
and pulled out by a rope and staked to the ground. It looks like a
diamond configuration. Pulling the lower end back in cancels out the
horiz component and lowers the andle of radiation. The wire is fed
with a 3/8 wave of coax (I used RG8X) to a relay switch box. This
length of coax is supposed to act like a stub, making the non-selcted
wires act like reflectors.
To switch from 80 to 75, I go outside and fold back about 10 ft at the
bottom. In the near future, I plan on adding some relays to do this
from in the shack, and if anyone has any suggestions on physical
construction details (what to use to keep water out, how to support
it, will the control wires bring RF into the shack, etc.), I'd apprec.
it.
I'm very pleased with performance, and at times see up to 20 db, F/B or
F/S depending on the path.
73 Barry
--
Barry Kutner, W2UP Internet: w2up@mindspring.com
Newtown, PA Frankford Radio Club
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