[TowerTalk] Coax Losses on 160 and 75?

[jimlux]

On 8/5/16 9:35 AM, Jim Brown wrote:
> Nothing "however" about it, Roger. Of course it's all skin effect, and
> copper-coated or clad onto steel has much greater loss than solid or
> stranded copper at these frequencies.
>
Skin depth in copper at 2 MHz is about 0.046 mm or 1.8 mil.

Is the cladding more than 10 mils (.25 mm) thick? In which case it 
doesn't matter what the core material is.

looking at Copperweld.com,
40% (the lowest resistance version) for AWG 13 (center conductor in 
RG-8) is 1.83mm in diameter, with cladding 0.829 mm minimum thickness.
This is WAY more than 5 skin depths.
21% conductivity (thinnest copper) AWG 13 has cladding 0.0549 mm, about 
one skin depth.

So it depends on what kind of copper clad steel they're using in the coax.


> BUT - there's a big difference between copper-clad Aluminum and
> copper-clad steel. RF resistance of copper-clad Al is NOT significantly
> different from solid/stranded copper at any frequencies where we are
> likely to use it.


I would generally agree. Aluminum is 60-65% of the conductivity in most 
of the "dead soft" alloys used for wire.   6xxx and 7xxx alloys are more 
like 30-45% depending on the specific composition and temper.