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 neonixie-l+unsubscr...@googlegroups.com. To post to this group, send an email to neonixie-l@googlegroups.com. To view this discussion on the web, visit https://groups.google.com/d/msgid/neonixie-l/b88eb341-ce5b-4c5b-8f00-def2b0f8b8c1%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
