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Re: [TowerTalk] solid THHN vs jacketed copperweld

To: towertalk@contesting.com
Subject: Re: [TowerTalk] solid THHN vs jacketed copperweld
From: "Lux, Jim" <jim@luxfamily.com>
Date: Tue, 27 Sep 2022 14:31:53 -0700
List-post: <mailto:towertalk@contesting.com>
On 9/27/22 2:22 PM, Steve Maki wrote:
I seem to recall ordering Copperweld wire, but it was a long time ago.

Just a quick note that after replacing the (insulated) #12 THHN with the same length insulated #12 "copper clad steel tracer wire", we could see no change in resonant frequency, so there seems to be enough copper cladding for my purpose at 3.5 MHZ.

There will only be an inch or so of wire exposed to the air at the center insulators, so that will be easy to monitor for corrosion over time (such as it is :-) Or I may coat the exposed wire with liquid tape.

73, Steve K8LX


Skin depth in copper at 4 MHz is 1.3 mils, 32 microns.


Copperweld

https://www.copperweld.com/application/files/4915/3833/2604/Welded_Copper-covered_Steel_CCS_21.pdf


21% CCS AWG 12 has 0.0808" diamter (2.05mm) with a nominal thickness of 0.0616 mm ( so about 2 skin depths at 4 MHz)


https://www.copperweld.com/application/files/7115/3833/2604/Welded_Copper-covered_Steel_CCS_40.pdf

40% CCS  has copper that is 0.2052 mm thick ( 6 skin depths)






On 9/21/2022 2:07 PM, Donald Chester wrote:
Steve Maki lists at oakcom.org Tue Sep 20 15:19:37 EDT 2022 wrote:

I had sworn off copperweld many years ago after noting that the copper
plating did not last forever.

Was that real copperweld, or was it copper-plated steel with only a minuscule layer of copper deposited on the surface, like the stuff used for electric fence wire?

Real copperweld has a thick copper jacket that is practically indestructible.  I use #10, salvaged from an abandoned railway telegraph line of yesteryear, scored free for the taking many decades ago.  You can beat it with a hammer or leave it buried in the soil (as ground radials) for years and the jacket won't come off unless it's deliberately removed with a file or grinding wheel.

That copper-plated junk begins to rust through in only a couple of years.  The copper is so thin that it probably has negligible benefit  from the skin effect; you are effectively using plain old steel wire.

Don k4kyv
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