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[TowerTalk] Copper Wire For Antennas

To: towertalk@contesting.com
Subject: [TowerTalk] Copper Wire For Antennas
From: Jim Brown <jim@audiosystemsgroup.com>
Reply-to: jim@audiosystemsgroup.com
Date: Wed, 28 Dec 2016 11:09:49 -0800
List-post: <towertalk@contesting.com">mailto:towertalk@contesting.com>
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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