[Lowfer] Wire Choice

[Lyle Koehler]

I have an old version (1965) of the Radio Amateur's VHF Manual, and here are
two excerpts about silver plating:

"Silver plating makes a measurable improvement in the Q of a VHF circuit; 5
to 10 per cent increase in 200-Mc. coils wound of copper ribbon resulted
from before-and-after measurements in the ARRL Lab..."

"Tests on typical items have shown no measurable improvement in transmitter
efficiencies through plating, but these have not been made on enough
circuits to be sure that no benefits are obtainable."

A more recent edition of the ARRL Handbook talks about improvements in coil
Q from silver plating, but doesn't give any numbers. One reason given for
using silver for VHF/UHF work is that the surface oxide that forms on silver
is a good conductor, while copper oxide is not. However, I've seen
discussions elsewhere that question this theory. Anyway, at LF the skin
depth is great enough so I don't think the conductivity of the oxide (or
sulfide, or whatever) layer makes any difference.

On long straight runs of wire I'd expect that silver would offer less than 5
per cent improvement over copper. The DC resistivity of silver is only about
6 per cent less than that of pure annealed copper, and AC resistance is
proportional to the square root of DC resistivity for a given wire size. But
if you work-harden that copper by dragging it over the trees, its resistance
will increase...

Lyle, K0LR