Before you consider silver plating a coil, here is something you should
know. At 2 MHz the RF skin depth in silver is 0.00178 inches. You need
about three skin depths of plating, that's about 0.0053 inches. If you
just walk into a plating shop and say, here silver plate this, you will
get about 0.00002 inches. "Highly polish-able" grade silver plating is
0.001 inches and costly. You need 5 times that. It's going to be
expensive. Most ham coils used at low frequencies are silver plated
just for appearance purposes.
Jerry, K4SAV
GEORGE WALLNER wrote:
>Dear Group Member,
>
>I have a question regrading the importance of silver
>plating inductor wire in high power TX circuits in the HF
>bands.
>
>I am just rebuilding my antenna tuner ahead of the 160m
>ARRL contest. The tuner configuration is a T with two
>inductors forming the horizontal arms with the variable
>capacitor in the vertical arm (i.e. between the junction
>of the two inductors and GND). The inductors use 3 mm
>diameter bare solid copper wire (good quality copper),
>with a solenoid diamater of 3" and length of 6". Each
>inductor is tapped for inductances of between 4uH and 33
>uH. Conductor spacing is 1:1.
>
>Would silver plating the conductors make a practical
>difference? There is no significant heating of the
>conductors now with full legal power.
>
>I have done some rough math on the difference in
>resistance, taking into consideration the skin effect at
>1.8 and 3.5 MHz, but there only seems to be an 8%
>difference between pure copper and silver plated wire. Am
>I missing something and should I replace the copper with
>sliver plated wire?
>
>TKS for your thoughts,
>
>George
>AA7JV
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>
>
>
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