[TowerTalk] Wire Rope

[Grant Saviers]

Beyond copper and copperweld, here are additional wire/wire rope choices 
- copper clad aluminum, aluminum, aluminum clad steel, and zinc/aluminum 
clad steel.  Links and some data.

Copper wire strengths at
http://navalfacilities.tpub.com/hdbk419a_vol2/hdbk419a_vol20054.htm
Solid Cu electrical wire seems mostly soft, so 14ga has break strength 
of 124lbs.  About $80/1000ft solid THHN 14ga.

The Cu over Al got a lot of traction when copper prices soared. It is 
pretty common in cheap imported stranded wire (eg speaker & irrigation), 
thin Cu over Al but I think pretty dead soft as to strength.  Unknown 
strength properties, but probably dead soft aluminum. (<20ksi yield)

I use Al electric fence wire for elevated radials.  9 gauge is available 
and it is cheap. So with Al, lower weight and RF performance the same as 
beam elements. It might stretch a bit, but less than soft copper.  I've 
not had stretch problems but the tension is less than in an antenna. 1/3 
the weight of copper, so less tension is needed for a given catenary. 
It is hard enough that unspooling needs to be done with care so kinks 
(hockles) aren't put in when it is stretched out.
14ga break strength of 215lbs.  1320ft for $60
https://www.tractorsupply.com/tsc/product/fi-shock-aluminum-wire-14-gauge-1-4-mile
9ga break strength of 500lbs & 1000ft for $75
https://www.agrisupply.com/gauge-aluminum-electric-fence-wire/p/31761/

Al over steel is used in two forms, pure Al wire wound over wound steel 
wire rope as a higher capacity strong HV distribution wire rope.  The HV 
wire rope is too large for ham use.

The Al drawn over steel (Alumoweld) wire is interesting since the steel 
core is solid high strength steel and the cross section area is 25% 
aluminum cladding.  For 0.10" dia (about 10ga) this yields an aluminum 
thickness of 0.0134", good enough for four skin depths, of about 0.003" 
at 1MHz.  I have a 90# spool of about 12ga which I bought it 15 years 
ago for a very long long wire over a canyon, never built.  It is very 
hard wire, high tensile strength, break 1000#.  I think difficult to 
find retail and not fun to work with.  Also available as wire rope. 
Claimed to be a good choice for applications exposed to 
contaminants/salt air.
https://www.aflglobal.com/productlist/Product-Lines/Fiber-Optic-Cable/Alumoweld-Aluminum-Clad-Steel-Overhead-Ground-Wire/doc/Alumoweld_Overhead_Ground_Wire.aspx

Al/Zn coated fence wire is 5 to 10% Al plus Zn at a spec of 0.8oz/sq ft. 
  Zn has half the conductivity of Al and one that of Cu.  Skin depth of 
Al at 1MHz is 123u or .005".  With 100ksi high strength steel break of 
14ga is well above 1000#.  Great for electric fences, 3x the life of 
galvanized.

Zn is 4.12oz/in^3 so over 144 sq in 0.8oz per sq/ft that yields a 
thickness of 0.0013", not thick enough at 1 or 10MHz (ignoring the 
improvement of 5 or 10% Al).

Grant KZ1W

http://www.rfcafe.com/references/electrical/cond-high-freq.htm


On 9/9/2020 17:51, john at kk9a.com wrote:
> Anyone that uses temporary wire antennas would prefer stranded over solid.
> There are many opinions on Copperweld wire for amateur radio.  Some
> differences may be environment, I tried it in Aruba and the steel quickly
> rusted and the wire became very fragile. Besides stranded vs solid,
> Copperweld is available in many different sized, from 2AWG to 24AWG and the
> steel can be high or low carbon. It would be beneficial to see the specifics
> of the Copperweld wire that is working for antennas.  I have had excellent
> results with inexpensive 14AWG solid THHN for temporary stuff.
> 
> John KK9A
> 
> Jim Lux wrote:
> 
> I'm sort of surprised they even sell stranded copperclad steel.. who
> uses such things?
> 
> single strand copperclad has been around for more than a century - miles
> of telephone wires on poles, for instance.
> 
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