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.
