The problem with using ordinary copper wire for antennas where the wire
is under tension is that it stretches. Mine high dipoles are under about
100# of tension (up 140 ft, fed with RG11), so every few years, I have
to let down my 80/40 dipole that's built with #10 THHN stranded and
circumcise it to keep it on frequency. I've since migrated to using #8
bare solid copper that I've stretched by tying one end to a tree and the
other end to the trailer mount of my SUV and pulling slowly until it
breaks. The result is close to being hard drawn, roughly AWG #9, and
about 15% longer. Antennas that I've built with this seem not to
stretch. Over the years, W6GJB and I have done this with at least 2,000
ft of #8.
73, Jim K9YC
On 8/6/2017 10:44 AM, Clay Autery wrote:
Correct... THHN is not intended for use as exterior antenna wire, but
it surely does work well... I can get it in any color I want and in a
2500+ foot spool, et al.
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