Mr. A. M. Fowler concluded in his article "Radio Frequency Performance of
Electroplated Finishes", Proceedings I.R.E.E Australia, May, 1970, page 148
etc, that:" It is often found that silver-plating a copper conductor increases
the radio frequency losses instead of reducing them as expected. The main
causes of this apparent anomaly are found to be: (a) the conductivity of an
electroplated metal is normally lower that that of the pure cast and wrought
metal ..."
He found that it was better to use a "plating with a high conductivity copper
plate, and then following this with a very thin layer of low conductivity
material to provide corrosion protection.
He shows in a table that even if silver is 5% better than copper in pure form
it is less conductive than copper when plated.
The next problem is that, according to the article, an intermediate layer is
frequently plated on the copper conductor to prevent tarnishing of the silver
plating. If that layer is part of the current distribution, depending on how
deep the skin effect allows the current to go, you might end up with
substantial worse condition.
I expect that better processes have been developed by the manufacturers of
radio equipment to address this issue but us, "common", radio hams have to look
out for this as we frequently have to rely on the normal facilities to do our
jobs, with processes that are there more for the look than for the electric
characteristics of their products.
With that article in mind I conclude that it is better to use polished and
varnished copper than silver plate. Add to that that copper can radiate heat
better than silver and, on top of that is cheaper, we have a win-win situation.
73 de,
Hans - N2JFS
-----Original Message-----
From: Bob K6UJ <k6uj@pacbell.net>
To: towertalk <towertalk@contesting.com>
Sent: Thu, 12 Oct 2017 20:07
Subject: Re: [TowerTalk] Fwd: (80 Meter yagi question) Cu <=> Ag
Since rf flows on the skin of the tube, I don't understand why silver plated
copper wouldn't be better than just copper.But what do I know, hihiBobK6UJ
From: Hans Hammarquist via TowerTalk <towertalk@contesting.com> To:
towertalk@contesting.com Sent: Thursday, October 12, 2017 1:26 PM Subject:
[TowerTalk] Fwd: (80 Meter yagi question) Cu <=> Ag I saw somewhere that,
unless you have solid, not electro-plated, silver you gain nothing plating
silver on copper. Electroplated silver have lower conductivity than OFHC
copper.Looks like polished copper is the way to go. I like the durability of Al
though. Is polished and varnished copper the best?Go figure,Hans - N2JFS
-----Original Message-----From: Jim Thomson <jim.thom@telus.net>To: towertalk
<towertalk@contesting.com>Sent: Thu, 12 Oct 2017 15:29Subject: [TowerTalk] 80
Meter yagi question##I did notice that stuff like RG-303 with its silver
plating, which is over the copper bonding..which is over the steel core..... on
s
oftware, appears to flat line about 9.2 mhz and below... power wise. My guess
is, the skin depth is deep enough such that the current is now into the steel
core. RG-400 doesnt have that issue, nor does RG-142. RG-304 also has a
steel core..same issues. ## But what the heck do I know,.. I just experiment.
Besides, copper tuning is cheap at any home depot or supply house. Then I
silver plate itwith the cool-amp goop...just so it looks nice. Bare copper
drives me nuts, I lose sleep over it, looks un finished to me. Later.... Jim
VE7RF
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