----- Original Message -----
From: "GEORGE WALLNER" <aa7jv@atlanticbb.net>
To: <amps@contesting.com>
Sent: Thursday, March 24, 2011 9:47 AM
Subject: Re: [Amps] copper vs steel /SS /brass conductors in a HF tank
circuit
> On Tue, 22 Mar 2011 13:06:04 -0700
> "John Lyles" <jtml@losalamos.com> wrote:
>> I'm pleased that Rob specified "in a HF tank circuit"
>>for his comment "they are so nearly the same that copper
>>strap is good enough; silver just looks pretty and
>>impresses people."
>
> Although for practical purposes on HF this is mostly true,
> there is a difference. Copper oxide is an insulator while
> silver oxide is a conductor. As the copper oxidizes, the
> skin current encounters increased resistance and moves
> deeper into the copper. At HF the difference will be very
> small.
>
> I have tested both bare copper and silver plated
> inductors, trying to measure the difference in Q, and with
> high RF currents (10 - 12A at 1.8 MHz) trying to measure
> the heating difference. I could never tell between the
> two. I have also tried to see if the Q of tarnished copper
> inductors was lower, but again, the differences were not
> measurable with my set-up. Still, I prefer silver plated
> inductors. It must be the looks. (I have also tested
> powdered-iron-core inductors. Even with silver plated wire
> they had lower Q-s (200 - 250) and heated up
> considerably.)
>
> 73, George, AA7JV
Do not confuse silver oxide with silver sulphate which is the black coating
which appears over time and is the source of many intermittent connections.
Properly sized and constructed toroids should not exhibit excessive heat.
Carl
KM1H
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