Terry, your assessment was very good. >From the volume of tubes examined over the years, the antenna-like center support was used on tubes dated between 6350 and 6415. The envelope is also a little taller. 6350 was the earliest production date I'd seen.
The underscore shape also varies from steep to shallow between lots throughout the production period. Most are relatively steep, with fewer than ~20% being shallow or nearly flattened. And requires some effort at matching if the underscore is illuminated in the application. I've not seen any other visible differences aside from these you pointed out. Regards, Jeff On Feb 27, 7:59 pm, Terry Kennedy <[email protected]> wrote: > I just completed an informal study of 50 or so B7971 tubes to see if > there was a pattern to the different markings and construction. I > figured I'd post it here in case anyone else finds it useful or can > add to it. > > The oldest tube I have has a date code of 6405. The newest one has a > date code of 6823. > > I have one tube with red print, in Burroughs-only (not Ultronics) > marking. > > The rest of the tubes have white print with a mixture of Burroughs- > only and Ultronics marking. > > The vast majority of the tubes have 64xx date codes. Presumably this > was the initial production for the LECTRASCAN units. > > I have 2 tubes with an "antenna" between the top mica sheet and the > glass envelope. One of these is my earliest tube, a 6405, and the > other has a 64xx (illegible) date code. This looks like an early > production method used to position the innards in the envelope. > > The underscore segments have a great deal of variation. Most of my > tubes have a constant "steep" angle to the underscores, while a much > smaller number have a shallow angle. I have a couple of in-between > tubes as well. The variation seems to be due to not needing the > underscore segment to line up with any of the other ones - if any > other segment was mis-shaped, it would be very obvious. -- You received this message because you are subscribed to the Google Groups "neonixie-l" group. To post to this group, send an email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/neonixie-l?hl=en-GB.
