On 12/29/16 10:22 PM, Roger (K8RI) on TT wrote:
How does the resistivity of the Copper Chloride (What you get with
Chlorine and moisture on the surface of the Copper wire) on the surface
of the Copper wire compare to the resistivity of Aluminum wire?
I looked up conductivity of various copper compounds - copper oxides,
copper chloride, etc.
They're all really high resistivity (not as high as Alumina), but more
importantly, some of them do dissolve in water (to some extent), which
changes their resistivity at DC (and RF, but it's a ion mobility thing),
so you might see a tiny difference between dry and wet conditions.
High, here, means resistivities in the 1000s of ohm-cm bucket, which is
where wet wood is Compare to copper at 1.68 micro ohm-cm - that's 9
orders of magnitude different.
Sea water is 20 ohm-cm
carbon is .005
In all cases, for any plausible thickness (up to the diameter of the
wire), no significant current flows in the corroded layer..
I ask
as I've seen number of posts on newsgroups where Al wire was being used
for radials.
Actually, aluminum wire would be a good choice for above ground antennas
- it might be cheaper than copper, even if you buy larger gauge to make
the resistance the same as copper. You'd need to go up in diameter (not
area) by a factor of 1.67 - that's about 4.5 AWG gauges.. (double
diameter is 6 gauges)
Roger (K8RI)
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