Gold plating is often done over nickel. Apparently the copper atoms tend
to diffuse thru the
thin gold layer. To stop this a plating of much less porous nickel is used
as an interface
layer between the copper and gold. I don't recall how thick the nickel is
but it is much thicker than
the gold layer. It may still be thin enough not to affect the RF resistance
of the coil but I just don't know
without investigating it further.
I can say that I have seen lots of gold plated cavities and RF
components in mostly military applications.
73
Bill wa4lav
At 04:42 AM 9/20/2009 -0400, ToddRoberts2001@aol.com wrote:
>Hi All,
>Thanks for the comments on Gold plating a tank coil.
>I think one thing that was overlooked is Gold plating is usually extremely
>thin, on the order of 1 or 2 microns, or 0.04 to 0.08 mil.
>At HF frequencies the skin effect depth is orders of magnitude
>greater than this, perhaps 2 to 4 mils, so the RF current stays 99% in the
>more
>conductive copper underneath the gold plating. The Gold plating does indeed
>protect the surface from tarnish, and would have an almost
>negligible effect on the RF resistance of the tank coil at HF
>frequencies.
>
>73 - Todd WD4NGG
>
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