AF11x transistors

[Pat Pending]

Hopefully pat pending will have some insider information

I will post this here as its more on topic than the thread that I started on the subject of packaging problems in early semiconductors. After a long delay I was eventually able to speak to my ex Mullard acquaintance George, and he was able to offer some more insights into the early production of transistors and how their subsequent testing and selection was carried out, possibly confirming what many of us have long suspected. I still intend to write up an article based on the information that George, the membership of this and other discussion boards, and my contacts have kindly furnished, and to have it hosted so it can be accessed by all as a technical history of the industry, but that will be a future project.

 As for the points raised in this thread, early germainium transistor production was pretty much a manual endeavor, and as such the resulting products were not only very expensive, but "production spreads" were also very wide. It is apparently correct that very few unique products were made, but instead differing types came from after production testing, rather than individual design. The manufacturers however wanted the "trade" (and no doubt the competition!), to think that everything produced was by design. Mullard for instance, dropped the production of the "long case" glass package that housed the audio output transistor (originally OC72 I believe) as out of spec devices couldn't then be easily passed of as something else! Enter the metal sleeve SO2 package, that saw service with many types, including the ubiquitous OC81 and even to the dawn of Mullard silicon production with transistors such as the BCZ11. All of the early germainium SO2 production at Mullard that fell outside any other type parameters were marked "OC10" (?) initially and offloaded to the hobby market. 

 Also confirmed was the marking of components to suit the order, as production methods improved, more examples from individual batches met the higher spec, and "badge down grades" were apparently order of the day, the type number guaranteeing the minimum spec  rather than indicating the performance capability of actual product. Later when production became more uniform with the advent of silicon transistor production, gain grouping was the only individual testing apart from that for functionality that was then carried out, sometimes only a few devices from batches of thousands being inspected.

Regards. Andy.

[Mark Hennessy]

Hi Andy,

That's a fascinating post that definitely confirms a lot of our suspicions!

Yes, definitely write it all up. And if you need help with hosting it, I'd be happy to advise or indeed oblige.

Brilliant stuff...

Mark

[Pat Pending]

Bit of a project for the long winter nights, but unfortunately (from the point of view of this exercise at least  ) its now spring! Ive got a large file on the computer now with info from all corners on this subject. As one elderly gent from the USA put it, this may be the last chance to get it from the horse's mouth! 

As I re-read Jeffreys comments on the AF118 I felt compelled to call George and ask about it this morning. His recollection was that it was a different construction that was intended to be an improvement on the 114. He also said that most of the production was carried out in the Netherlands but were often shipped unmarked, and then branded as British when finally codified, the 118 apparently found its way into the front ends of many a radio tuner, though I've not come across any myself, however as the attachment shows, the radio contruction hobby appreciated them for making sets with. 
Regards. Andy.