[Collins] S-Line: Systemic Socket Rot?

Dr. Gerald N. Johnson geraldj at weather.net
Thu Mar 18 17:18:49 EDT 2010


Good point on the moisture, though the original post said some sockets 
corroded and some didn't IN the same radio. And only in receivers with 
round emblems without Rockwell-Collins emblems, so later production, 
possibly in places other than Anamosa, Iowa like Toronto.

Different metals against each other corrode at different rates and 
cadmium vs aluminum is one of the slower rates as I recall. The table in 
the ARRL Handbook on the electropotential series shows those with the 
most and least voltage differences.

I've had my receiver since 1964 and I haven't dug for corrosion. Its 
open on the bench for new capacitors and tube socket corrosion hasn't 
jumped out at me. I need to box it up for moving soon. I'll look before 
I put the case on.

One other thing that helps performance is to loosen and tighten ALL tube 
socket mounting screws since many tube circuit grounds are made through 
the tube socket rings.

73, Jerry, K0CQ, Technical Adviser to the Collins Radio Association.

On 3/18/2010 2:41 PM, Les Groberman wrote:
> Basic chemistry tells us that corrosion is a result of water and other
> liquids in their nefarious forms getting into the works. Shorted dissimilar
> metals that are present can form a battery that corrodes in time.
> May I suggest that to preserve things, you must keep things very very dry at
> all times. A little heat helps too. A good excuse for firing it up
> regularly. That should take care of most of corrosion.
>
> I hope you have lots of fun playing with the Collins S-line equipment. It's
> really remarkable equipment.
> Les
> VE7BLP
>
> -----Original Message-----
> From: collins-bounces at mailman.qth.net
> [mailto:collins-bounces at mailman.qth.net] On Behalf Of Dr. Gerald N. Johnson
> Sent: Wednesday, March 17, 2010 5:45 PM
> To: collins at mailman.qth.net
> Subject: Re: [Collins] S-Line: Systemic Socket Rot?
>
> 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.
> ______________________________________________________________
>


More information about the Collins mailing list