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Topband: ground radials & conductivity

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Subject: Topband: ground radials & conductivity
From: "k1fz" <>
Date: Mon, 15 Dec 2014 11:14:56 -0500
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In Broadcasting, we used silver plating of tuned circuits often as copper 
oxide, depending upon the degree of oxidation, is a poor conductor, 
Silver oxide is a much better conductor than copper oxide. 

In the High powered short wave station that I worked. the ABB Swiss made 
transmitter plate tuning inductor was made of oxygen free copper, and water 
cooled. We used deionization resin beads to keep the water in good shape. One 
time as the water quality dropped we noted a shift in tuning that was traced to 
the water cooled Comet vacuum variable capacitors. Copper oxide, in the water, 
was causing a change in capatance. With Testing & research we found that copper 
oxide has stages of conductivity the last, black in color, is close to an 
insulator, that may act as a dielectric.

Ground radials can suffer varying degree of copper oxidation depending, upon 
soil, electrolysis, and  other factors. 
Covered wires can eventually have water intrusion. In the 1990's I used 
enameled coated wires, that have worked well so far.

Electrical and thermal conductivity have a QUITE similar order of published 

Electrical conductivity of metals

Thermal conductivity of metals

Note: The backstay we found of the old 1920's Belfast  radio station was 
galvanized iron. The galvanized surface was in good condition after so many 
years in the ground) 
In the aging process have wondered how Zinc oxide compared with copper oxide.  
(Copper-weld vs zinc coated electric fence wire)  Zinc is not nearly as good to 
start with.



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