On Wed,2/10/2016 4:41 AM, Don Wilhelm wrote:
Clay,
You should be able to find suitable pulleys and cord at a marine
supply store.
Pulleys yes. Cord at a marine store will be expensive. Here's a link to
the company that makes great antenna rope that is resold by several
large ham vendors. 3/16-in is enough for strength, but 5/16-in is easier
to grip if you need to pull it to put a lot of tension on it.
http://www.synthetictextilesinc.com/supportham.html
I would recommend using hard drawn copper for the wire rather than
THHN. You can find THHN at your local DIY store. For hard drawn
copper, look at The Wireman www.thewireman.com.
The only issue with THHN is that it stretches if under load. I have high
dipoles under about 100# tension, and I have to trim them every few
years. Another way to do hard drawn copper is to buy #8 bare copper at
your local big box store and stretch it yourself. Cut a few hundred
foot length, tie one end to a tree or telephone pole, the other end to a
trailer hitch, and pull VERY slowly until it breaks. The result is hard
drawn copper that is 15-20% longer.
Before you commit resources to a loop, take a look at the antenna
planning applications notes on my website. k9yc.com/publish.htm
In general, low horizontal antennas have poor efficiency. Antennas that
lack common mode chokes at the feedpoint are noisy on RX, and it's not
practical to choke most non-resonant antennas. If ground conductivity is
good in your area, a roof-mounted multi-band vertical could be an
excellent choice. Study the FCC map. To choose a vertical, study the
N0AX/K7LXC report on their measurements of the performance of a dozen or
so HF verticals. Available from Champion Radio Products. Well worth the
$35 or so that it costs. While you're there, also buy the report on
tri-band Yagis -- you'll benefit when buying something to put on that
tower when you get around to it. This work was done about 15 years ago,
but the laws of physics don't change. :) N0AX is now editor of the ARRL
Handbook and the ARRL Antenna Book -- he's a fine engineer who really
knows his stuff.
https://www.fcc.gov/media/radio/m3-ground-conductivity-map
73, Jim K9YC
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