Thanks Jim.
I know this is a scenario of diminishing returns...how many skin depths
does one shoot for?
On 9/27/2022 5:31 PM, Lux, Jim wrote:
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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