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

[Richard Smith]

Recently, I did some research into silver plating here at work. I found that there are two basic types of silver plating:
Matte Finish: This is almost 100% silver plating. The plating is very conductive, a little better than copper. It is kind of soft, so it is not good mechanically for some applications.
Bright Finish: Brighteners are added to the silver plating bath, which produces a bright finish, which is also harder and better mechanically for applications that need a harder finish. There is a variety of brighteners used by different plating houses, and the conductivity varies between brightening agents. But all of the brightening agents reduce the conductivity significantly, from approximately 10 to 75%.
We use only Matte Finish silver plating for our filters and housings at work (microwave filters), because we need the good conductivity for low insertion loss.
It is not easy to find a plating house that does Matte Finish silver plating. In our local area, 90% of the platers do only Bright Finish silver plating, because it is more commonly used. The few that do Matte Finish have separate tanks for their Matte Finish plating, and they support the needs of the communications and aerospace industries.

Poorer performance after silver plating might have been the result of Bright Finish silver plating.
73, Rich, N6KT

      From: Howard Hoyt <hhoyt at mebtel.net>
 To: towertalk at contesting.com 
 Sent: Friday, October 13, 2017 11:24 AM
 Subject: Re: [TowerTalk] Fwd: Fwd: (80 Meter yagi question) Cu <=> Ag
   
Hi Bob,

Two data points:

1) When I worked at a radio astronomy lab as a college student the 
engineers there said silver plating the machined copper cavities ruined 
their performance which I didn't understand at the time.

2) The broadcast equipment I maintain uses aluminum straps and tank 
components in the plate cavities and running at quite high powers the 
straps themselves seem to run cool, except for where they are tied to 
the anodes of the 4CXxxxxx tubes.  I believe they are intended to help 
pull heat away from the anode seal in that usage.

If that study is to be believed, perhaps the silver-plating thing in ham 
equipment is a vestige of earlier manufacturing beliefs and techniques, 
plus corroded copper is difficult to clean and looks like hell?  Based 
on the study, lacquered polished copper or over-sized aluminum would 
appear to be the winner for coil construction.

Howie - WA4PSC


On 10/13/2017 7:06 AM, towertalk-request at contesting.com wrote:
 >>Not trying to dispute the study but why then do amplifier
 >>companies use silver plated tank coils in their amplifiers ?

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