[TowerTalk] Fwd: Fwd: (80 Meter yagi question) Cu <=> Ag

Thu Oct 12 23:32:52 EDT 2017

 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 at pacbell.net>
To: towertalk <towertalk at 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 at contesting.com> To: towertalk at 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 at telus.net>To: towertalk <towertalk at 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 software, 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  ______________________________________________________________________________________________TowerTalk mailing listTowerTalk at contesting.comhttp://lists.contesting.com/mailman/listinfo/towertalk______________________________________________________________________________________________TowerTalk mailing listTowerTalk at contesting.comhttp://lists.contesting.com/mailman/listinfo/towertalk ______________________________________________________________________________________________TowerTalk mailing listTowerTalk at contesting.comhttp://lists.contesting.com/mailman/listinfo/towertalk