[TowerTalk] Tarnished connectors

[Wes]

I agree.  Also when going to gold, most  (all)  commercial plating shops will 
put down a nickle barrier on the base metal then plate with gold.  If the gold 
is too thin and the skin depth too deep, your gold surface is RF wise, actually 
nickle.

I once designed a test station for X-band IMPATT diodes and we built the 
prototype 1/4-height waveguide oscillator in-house and did our own plating in 
the model shop.  Since we were going to calibrate and supply a number of these 
to our IMPATT vendors, we had the design replicated and sent the plating job to 
an outside vendor.  If you simply specify minimum total plating thickness, you 
get lots of nickle and a flash of gold.  It took lots of hours to figure out why 
we weren't getting any power output.

If the connectors are silver, I use Tarn-X to brighten them.

Wes N7WS


On 8/20/2019 1:10 PM, Richard (Rick) Karlquist wrote:
>
>
> On 8/20/2019 10:58 AM, k7lxc--- via TowerTalk wrote:
>>>    Just wondering if anyone has found a way to remove the tarnish off of 
>>> older connectors.?? The tarnish is not effecting the usage, but does 
>>> distract from the appearance.
>>      It they're silver, the visible silver oxide is a conductor so no need to 
>> do anything.
>>      Removing the tarnish won't affect the signal so I wouldn't bother. 
>> Around here, the question is whether it makes a difference to the DX station. 
>> If it makes a difference - > Cheers,Steve     K7LXCTOWER TECH
>
> This topic is actually quite controversial.  First of all, AFAIK,
> "tarnish" is silver sulfide, not silver oxide.  Numerous
> references say silver sulfide is NOT a good conductor,
> even going to the extent of "debunking the myth" that it is.
>
> When I worked for HP in atomic clock R&D, we discovered
> that the silver plated microwave waveguides in our
> model 5061B tarnished in areas where coal (containing
> sulfur) was burned.  This would cause RF to leak out
> of the waveguide and bounce around the chassis and
> leak back in.  Removing the top cover (which should have
> had no effect) would change the RF reflections.
> For complicated reasons, this resulted in a frequency shift of the standard, 
> which was called the "top cover effect."
>
> The fix for this was to disassemble all the waveguide
> pieces, clean up the tarnished surfaces, and then
> reassemble everything.
>
> I made sure to eliminate any silver plating and
> replace it with gold plating in the model 5071A,
> which replaced the 5061B.
>
> Unfortunately, I don't remember what was used to
> remove the tarnish, but you might be able to find
> out by reading papers about the top cover effect written
> by an Italian professor named de Marchi.
>
> Rick N6RK