[Amps] RE : copper or silver in tank circuit?

[Will Matney]

Bill,

That's all I could think it would be used for, where the skin effect increases with frequency. I'll about bet that military stuff wasn't plated very thick either, maybe 1-2 mils at the most. The only other place in electronics is electrical contacts. Gold is just too expensive to be used as a very thick plating. When I did some gunsmithing years back, I checked on the price of some small gold anodes for plating small parts. Needless to say, over the cost, I didn't invest in it. For HF work, I cant see any benefit really, especially if the coils they're using are still the same size. My opinion is, the gold coils are there as an extra money maker and sales gimmik in these last Alphas.

Best,

Will


----- Original Message -----
From: "Bill Fuqua" <wlfuqu00 at uky.edu>
To: hermans <on4kj at skynet.be>, "'Steve Thompson'" <g8gsq at ic24.net>, amps at contesting.com
Subject: Re: [Amps] RE :  copper or silver in tank circuit?
Date: Fri, 17 Jun 2005 10:35:18 -0400

> 
> Gold has low conductance, but gold plating is usually very thin.  Since it
> has low conductivity it has greater skin depth and since gold plating is
> usually around a micron thick most of the current flows thru the material
> under it. However, it does provide for a good deal of protection for that
> underlying material from corrosion.  I have junked a lot of military
> microwave stuff in my younger days that was used in aircraft. The cavities
> were gold plated inside and out.
> 
> 73
> Bill wa4lav
> 
> 
> At 11:14 PM 6/16/2005 +0100, hermans wrote:
> > hoy All,
> >
> > Silver plated wire, we only used it in applications where very high Q
> > was necessary. It helped stability in oscillator coils, since silver
> > oxide has the same resistance as silver. So it is also OK for contacts,
> > when Current passing through is not very low. ( less then few tenths of
> > micro Amps).
> > Gold .....is used for the same raisons, its good looking, but
> > expensive.....
> > Silver plating can easily be done with silver cyanide, but be aware it
> > is a very very dangerous procedure when done at home without good
> > knowledge and precaution. SO DON&#8217;T DO IT AT HOME.
> >
> > Jos on4kj
> >
> > -----Message d'origine-----
> > De : amps-bounces at contesting.com [mailto:amps-bounces at contesting.com] De
> > la part de Steve Thompson
> > Envoyé : jeudi 16 juin 2005 17:23
> > À : amps at contesting.com
> > Objet : Re: [Amps] copper or silver in tank circuit?
> >
> > Larry Carman wrote:
> > > I was told by a pro amp builder to leave out the silver and use copper
> > only
> > > in the tank circuit. Reason: because it helps prevent parasitic on the
> > > higher frequencies. I'm speaking of HF amps working to 30 MHz. Any
> > Merits to
> > > this???
> >
> > Not to mince words, it sounds nonsense to me. If that's the
> > difference between a amp that's stable and unstable, them
> > there's something much more fundamental needs fixing.
> >
> > I recall an article in RF Design (but not in fine detail)
> > where the writer argued that oxidised copper wasn't as much
> > of a problem as people sometimes think, as the current will
> > tend to head for lower resistance paths, driving it deeper
> > into the wire/tube/stripline.
> >
> > Will mentioned tin plating - I've seen harmonic filters
> > (VHF, 200Wish) burn up pcbs and unsolder chip capacitors
> > from the heat when enamelled wire was replaced with tinned
> > to save on preparation time. Where the loaded Q is low, it
> > will probably matter less.
> >
> > Steve
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