Galvanized can be a problem in some soils. This is the reason that
galvanized ground rods are no longer recommended in most applications (I
think ON4UN even has a pictured of a rotted galvanized ground rod in his
book).
Galvanized is a problem here. In the air on in the ground, galvanized does
not last long. My fence wire antennas last several years at the most, but
the same wire goes away quickly in contact with soil. It is not just the
soil type, but also electrolysis from ground currents that causes rapid
decay issues.
Copper-clad steel ground rods are more common and will generally hold up
much better in typical soil conditions. I would assume the same would
apply to galvanized steel and copper radial wires. I'd be careful using
galvanized wire for radials without at first testing it to make sure it
would last. It would be a shame to invest time and effort in a radial
system just to see it rot away in a few years!
There is far too much worry about copper oxide on HF (or lower) conductors.
Other than showing a visual patina, effects are pretty meaningless at HF
unless actually in a connection where current is forced through the oxide. I
wouldn't worry a bit about using bare copper surface.
I use galvanized fence wire, but it goes away fast if in earth contact. It
marginally lasts long enough suspended in air, and it always has to be
greased if it contacts stainless or metals other than things way off at the
far anodic end of tables. To solve that with the headache of grease, a
Teflon insulated wire downlead (which is usually silver flashed) or bare
copper can be soldered to the fence wire (if you don't overheat the fence
wire and burn off the galvanizing). Depending on the wire I might see ten
years in air, sometimes as little as three or four, before a suspended wire
needs replacement.
73 Tom
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