One skin depth is 2.6 divided by the square root of the frequency in MHz -
that's the answer in thousandths of an inch. (ITT 'Reference data for Radio
Engineers') So at 10 GHz, one skin depth is 26 microinches, or about 1 micron.
You would need at least 3 skin depths. Whether or not the plating is smooth
enough, I do not know. I have heard that there are two forms of silver plate
(basically I believe hard or soft) and one is much better for RF than the
other. At HF, for any practical thickness, it doesn't matter.
73
Peter G3RZP
========================================
Message Received: Mar 03 2014, 05:24 PM
From: "Roger (K8RI)" <k8ri@rogerhalstead.com>
To: amps@contesting.com
Cc:
Subject: Re: [Amps] Cool Amp Silver Plating
On 3/1/2014 5:40 PM, Dr. David Kirkby wrote:
> On 1 Mar 2014 20:57, "John Lyles" <jtml@losalamos.com> wrote:
>>
>> We use it often at work. It's expensive. It doesn't do squat for
> improving the conductivity of surfaces like cavities and inductors for RF
> current, as Peter pointed out. That requires at least 3 to 5 times the skin
> depth
>
> What controls the thickness of the cool amp? Can one not repeat the
> process to get a thicker coating or does that not work?
>
I believe it's an ion exchange, which would only be a few atoms thick.
Once the base metal is completely covered, I doubt repeated applications
would add much additional thickness as the mechanical rubbing of the
material no longer contacts the base metal.
> If fixed, do you know what the thickness is? I was wondering if it would
> be useful for 10 GHz, where the skin depth is a lot less than at VHF/UHF
Searches reveal several sources saying 0.0025mm or 9.84 * 10^-5" or
0.0000984" if I placed the decimal correctly.
0.0025mm/25.4mm per in = 9.84 * 10^-5 in.
I can not verify the authenticity of those numbers, but they "appear"
to have come from CoolAmp.
http://www.docin.com/p-533501287.html Chinese..I think. Scroll down in
the English window past the Bellvile washers and there is a CoolAmp page
http://www.thew.com.au/index.php?option=com_aceshop&Itemid=137&route=product/product&path=37&product_id=271
From Australia: Looks like the blurb above without the scrolling.
Both only say it's good for reducing contact resistance
73
Roger (K8RI)
>
> Dave
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