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

To: "towertalk@contesting.com" <towertalk@contesting.com>
Subject: Re: [TowerTalk] Fwd: Fwd: (80 Meter yagi question) Cu <=> Ag
From: Bob K6UJ <k6uj@pacbell.net>
Reply-to: Bob K6UJ <k6uj@pacbell.net>
Date: Fri, 13 Oct 2017 03:52:45 +0000 (UTC)
List-post: <mailto:towertalk@contesting.com>
Not trying to dispute the study but why then do amplifier companies
use silver plated tank coils in their amplifiers ?
 

BobK6UJ



      From: Hans Hammarquist via TowerTalk <towertalk@contesting.com>
 To: towertalk@contesting.com 
 Sent: Thursday, October 12, 2017 8:35 PM
 Subject: [TowerTalk] Fwd: Fwd: (80 Meter yagi question) Cu <=> Ag
   

 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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