There's another very practical issue with the use of ordinary copper
wire for antennas hung between supports -- copper stretches! I found
that my high dipoles strung between trees at 130 ft with the tension
needed to keep then sort of horizontal with 160 ft or so of RG11 trying
to drag them to the ground stretched enough that I must lower them and
circumcise them every few years.
A far better solution is to buy #8 solid bare copper from your local big
box store and hard draw it to #9. In effect, you're pre-stretching it.
:) Pretty simple. lay out 200-250 ft of it, tie one end to an immovable
object (tree, utility pole) the other end to a trailer hitch on your
towing vehicle, and very slowly pull while an assistant observes. When
it breaks, coil it up and repeat. With assistants, I've done this for
four 1,000 ft spools, each of which yields about 1,200 ft of #9. :)
BTW -- I've had thousands of feet of THHN in place as radials and as
antenna elements here in Northern California, 5 miles from the Pacific.
When I've had the occasion to remove the insulation to repair a break or
to solder to lugs at a radial plate (replacing connection only with the
lugs), I have found virtually no visible corrosion under the insulation
unless there was a break in it, and if I strip past the break, it's very
clean. The THHN I've used is nothing special, simply whatever I buy at
the big box stores. My current practice is to use the #8 bare copper
stretched to #9 for load-bearing elements and #12 or #14 THHN for
parallel elements in 80/40 fans and #14 THHN for radials, whether
elevated or laying on the ground.
73, Jim K9YC
On Tue,12/27/2016 4:33 PM, Guy Olinger wrote:
Stripping insulation from a 500 feet spool of #12 THHN from a big box
store is easy-peasy. Once you've seen it done, you'll kick yourself in
the butt for ever buying bare wire from the online stores at double
the cost. Or for leaving it on up in the air to go bad and ruin the
copper.
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