[Amps] Silver Strap

[Alex]

I would also like to remind you of something: if my memory serves me still
right, all oxides except silver are insulators so that if they appear
they're out of the game as conducting media.
My guess is that copper oxides do the same so that it's only natural for the
current to "bury" itself under the oxide layer to follow the least
resistance path.
One thing I can tell you: don't gold plate anything carrying RF especially
not at the higher frequencies! I've had a case when microstrip was gold
plated and completely detuned by the altered velocity factor that resulted.
The best thing, I think, is to use bare copper and possibly, spray a VERY
thin layer of acrylic lacquer over it.
Alex	4Z5KS  

-----Original Message-----
From: amps-bounces at contesting.com [mailto:amps-bounces at contesting.com] On
Behalf Of Steve Thompson
Sent: Friday, July 11, 2008 10:05 AM
To: amps at contesting.com
Subject: Re: [Amps] Silver Strap

> Folks,
> 
> I used to think silver plating was a big deal until I ran a bunch of 
> tests.  See http://www.bnk.com/W0QE/inductor_Q_tests.html  for the 
> results.  Silver is only 7% better than copper and with reduced 
> resistance comes reduced skin depth resulting in only about a net 
> difference of 4%.  Lore has it that the corrosion on copper increases 
> the resistance but my tests did not show that to be true for copper I 
> oxide (reddish brown), copper II oxide (black), and copper carbonate 
> (blue green).

Many years ago there was an article in RF Design magazine that 
looked at this - the analysis was that if the tarnished surface is 
higher resistivity than the underlying metal, than the current 
tends to to concentrate in the lower resistance area under the 
corrosion so the effect on Q/loss etc is less than you might 
expect from appearance.

Steve
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