[Boatanchors] Dark deposits on rotary switch wafers

[David C. Hallam]

Most likely it was silver sulfide.  Most silver tarnishing is due 
formation of the sulfide.  It comes from the combustion of natural gas 
(methane).  Methane is odorless so a compound call mercaptan which is 
sulfur bearing compound to make it smell when there is a natural gas 
leak.  Silver does not form an oxide at normal temperatures.

http://www.dtic.mil/dtic/tr/fulltext/u2/a196217.pdf

This explains the formation of silver sulfide.

David
KW4DH


On 8/13/2018 2:20 PM, K5MYJ wrote:
> I have a SX-111 that had a problem with the band switch.
>
> I tried cleaning it with DeOxit several time without success.
>
> For some reason a black crud built up on the rotors. I finally had to 
> scrape it off with an X-Acto knife.
>
> I have no idea what the crud was.
>
> Bob Macklin
> K5MYJ
> Seattle, Wa.
> "Real Radios Glow In The Dark"
> ----- Original Message ----- From: "Kenneth Grimm" <grimm at sbc.edu>
> To: "Rob Atkinson" <ranchorobbo at gmail.com>
> Cc: "Boat Anchors List" <boatanchors at mailman.qth.net>; "Grant 
> Youngman" <ghyoungman at gmail.com>; "HL1FB" <yonglee at yonsei.ac.kr>
> Sent: Monday, August 13, 2018 7:25 AM
> Subject: Re: [Boatanchors] Dark deposits on rotary switch wafers
>
>
>>  "..But we're talking about radio hardware, not a tea service or
>> the Stanly Cup..."
>>
>> I couldn't agree more!
>>
>> Deoxit D5 is all you need.  Please avoid destroying a perfectly good 
>> switch
>> by using a Dremel tool.  With a brute force treatment like that one 
>> little
>> slip and.....
>> Deoxit won't make it shine, but WILL keep it working if all that is 
>> wrong
>> is a coating of silver oxide (which is a conductor anyway).
>>
>> 73,
>> -- 
>> Ken - K4XL
>> BoatAnchor Manual Archive
>> BAMA - http://bama.edebris.com
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