FYI, crystals in glass cases are still being manufactured. Total Frequency Control in the UK list some in the H/C-26U type case. See: http://www.tfc.co.uk/pdfs/HC-26-U_TFC.pdf ( I have no connection to this company.)
Mark On Friday, May 18, 2018 at 4:37:17 PM UTC-5, Terry Kennedy wrote: > > On Friday, May 18, 2018 at 2:02:32 AM UTC-4, Tomasz Kowalczyk wrote: >> >> I suppose there are two reasons why so many pins are present. One is >> locating the right position of the tube - if you skip most of the pins, >> then orientation can be located only by judging where the front of the tube >> is. If there is only one way to put something in something, then the risk >> of something wrong happening is minimized. >> > > In the referenced tube, the entire inner ring of pins could be omitted > without losing positive keying, and none of the inner ring pins are used on > that tube. > > >> Also, if the socket has all 27 slots present, but the tube doesn't, >> someone might thing his tube is broken, as it has less pins. >> > > I doubt this was much of an issue in the original application, as assembly > (and most likely repair) would be done by people familiar with the product. > > >> The other reason is that as far as I know the stems weren't produced by >> the same companies, or at least not in same factories, so ordering unique >> bases was more problematic than just purchasing same type as for the other >> tubes. >> > > This is more likely. Economy of scale may mean that it would be more > expensive to omit the pins. And if the bases were made by a different > company, the rejected part ratio was not the tube company's problem, as > long as rejects were found by the supplier before the tube company > assembled the final product, and the supplier's prices remained low enough. > That can sometimes be problematic - I was called in to fix a disk drive > design problem in the 80's where the drive manufacturer was having a 90%+ > incoming reject rate on outsourced hybrid modules which were made by one of > the most well-known companies in that field. > > Back on tubes, the omitted-pin business seems to be more common on tubes > where a) the base was not part of the evacuated system and b) there was > already some positive keying method (such as octal base) in place. It was > very common for TV picture tubes to not have all pins populated, for > example. > > At the glass company I worked at, most production was for relatively > high-cost / low-volume products. One big exception was a part (something > like BC1237 - I forget the exact number) which was the base + lead assembly > we made for Motorola, used for a 3.58MHz crystal in TV sets. Those went out > in orders of 10's of thousands at a time. We did all sorts of esoteric > stuff, like crystal housings where everything but the lead wires and the > base / cap seal ring were clear glass. That was for a military application. > -- You received this message because you are subscribed to the Google Groups "neonixie-l" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send an email to [email protected]. To view this discussion on the web, visit https://groups.google.com/d/msgid/neonixie-l/b9f26e8f-0b7e-4052-8071-d36e55cf6f0b%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
