[TowerTalk] Copper Wire For Antennas

[Jim Brown]

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.