[Collins] S-Line: Systemic Socket Rot?

[Dr. Gerald N. Johnson]

Probably a combination of changes in plating materials, and vendor. By 
the early 70s, tube sockets were not as available as they had been and 
cadmium was being recognized as less healthy, though it had been 
considered a good plate for mechanical items. Then since the tube socket 
rings also were used for grounds and included grounded lugs, there might 
have been a need for a stronger flux, that didn't get washed off and 
that contributed to socket corrosion.

On 3/17/2010 12:39 PM, Robert Jefferis wrote:
> Greetings all,
>
> Here is an off-the-wall question for your entertainment. Still likely to be regarded as a newbie, I starting collecting, refurbishing, and using S-Line gear about 7 years ago. In that period, I have shuttled about a dozen units through my shack, each change intended to increase quality of the small collection. In my quest for better examples of 75S-x receivers and 32s-3 transmitters, I have become generally stumped on RE units. Almost all examples I see, whether in person or via photos suffer "selective socket rot".
>
> OK, "socket rot" is how I refer to a tube socket that exhibits nearly 100% corrosion or plating failure of the metal mounting collar. I am not talking about units that have obviously been used or stored for extended periods in poor environments. These typically show corrosion symptoms everywhere. I am referring to selective socket rot, where in many otherwise excellent radios, everything is clean and generally free of corrosion symptoms, but anywhere from about 2 to 4 or 5 sockets are completely corroded around the collars, while other sockets in the same radio are bight and shiny, with maybe very minor pitting (or clean up so). Thanks to Internet photo sources and of course fleabay, dozens of interior photos began to reveal what I now think might be systematic trends in this regard. First, the problem seems to be more prevalent in later units, especially RE. Second, it seems more prevalent in the 7-pin sockets than it is in the 9-pin sockets. Interestingly, both of my 75S
-3s
>
>    have beautiful sockets throughout. The RE 75S-3Bs I have acquired have, you guessed it: selective socket rot.
>
> I have physically seen 2 notable exceptions. Both were RC logo units with the coated chassis, belonging to a well known West Coast collector. All sockets were like new. I wonder if this is symptomatic of lower and lower plating quality as time went on, or bad batches, or?
>
> Attempts to clean these socket collars have clearly shown that in most cases the plating has failed and you wind up cleaning/polishing the underlying metal.
>
> So, has anyone noticed this, am I hallucinating, or maybe this is something the experts already know? Cheers.
>
> 73, Bob KF6BC
> CRA member
>
73, Jerry, K0CQ, Technical Adviser to the Collins Radio Association.