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Re: [Amps] Cleaning air-wound coils

To: "Larry Benko" <>, "Dan Zimmerman N3OX" <>
Subject: Re: [Amps] Cleaning air-wound coils
From: "David Cutter" <>
Date: Wed, 5 May 2010 18:15:33 +0100
List-post: <">>
"Radio Frequency Performance of Electroplated Finishes" by AM Fowler and an 
addendum page are ancient manuscripts that might bear looking at again.

I'll send them to you if you can't find them via Google


> Thanks for the plug Dan.  I did the tests you mentioned primarily at
> 28MHz a couple years ago.  Increasing the wire size 1 gauge is better
> than silver plating assuming you have adequate spacing between the turns
> so that the Q is not impaired by the turns being too close together.  I
> still like painting the coil with high temp barbeque paint which had
> absolutely no Q reduction and looks very cool.
> 73,
> Larry, W0QE
> Dan Zimmerman N3OX wrote:
>>> Has anyone done any tests on the comparative Q between Silver plated,
>>> enamelled and tinned wire coils?  I've always felt that factory
>>> enamelled wire stood a much better chance of retaining a good Q for a
>>> long time as the surface of the copper should still be pristine under
>>> the enamel.  The other question is how long the enamel will last if used
>>> at high temperatures.  Carbonised enamel is probably worse than
>>> tarnished tin!
>> W0QE found that there wasn't a substantial difference between shiny 
>> copper
>> and terribly corroded copper:
>> Metallic platings should be analyzed based on the skin depth of the 
>> plating
>> at the frequency of operation... if the plating is thin and the 
>> conductivity
>> is low, more current will just flow in the base metal.
>> W8JI had this to say about Miniductor stock, which I think is all tinned,
>> right?
>> "Miniductor-type coils have a surprising amount of Q for the wire size, 
>> and
>> maintain Q better as self-resonance is approached than larger coils.  "
>> I've heard others on this reflector suggest that silver or other fancy
>> plating is good to make the coils look pretty, and I would tend to agree
>> with that based on the evidence I've seen.
>> 73
>> Dan
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