@Greg. They are all NOS NIB. @Chuck. I like the domed tube too, but gave up ever trying to find any that worked. Like you, I am always more impressed with the National Electronics version of whatever Burroughs produced. On Friday, December 11, 2020 at 10:14:38 AM UTC-5 Chuck wrote:
> @gregebert: 6844A is a non-mercury tube. It has a relatively short > lifespan, and yes, one of its properties is that > > during use, the cathode material does get deposited on the glass. They > do silver up quite noticeably over several years of use. > > They also get sputtered cathode material on the tiny ceramic separator > washers in the cathode stack which eventually cause > > multiple cathodes to glow when only a single cathode is grounded. After > the first ten years of operation in my 6844A clock, I recently > > swapped out a tube that started having digits 7 and 8 on together. Moved > that to a location in the clock where only digits 0 through 5 are used. - > Chuck > > > ---- Original Message ---- > From: "gregebert" <[email protected]> > Sent: 12/11/2020 9:47:35 AM > To: "neonixie-l" <[email protected]> > Subject: [neonixie-l] Re: Bad batch of Burroughs 6844A nixies > > Paul - Do any of your failed NOS units have a black or silvery coating > inside the glass ? I'm hoping that is caused by sputtering, and not simple > aging. > > On Friday, December 11, 2020 at 6:32:45 AM UTC-8 Paul Andrews wrote: > >> I have about 12 6844A, all NOS, none of them work - they show the same >> symptoms that you described. >> >> On Friday, December 11, 2020 at 1:45:30 AM UTC-5 gregebert wrote: >> >>> I have not been able to figure that out for years. You would think the >>> internal leads were coated with an insulator so they dont glow, or perhaps >>> they use a different metal with a higher workfunction than the actual >>> cathodes, so they would not glow in normal circumstances. But when the >>> cathodes are still visible, I dont understand why they have no glow. I >>> doubt they would be selectively plated with another metal, which completely >>> sputtered away, leaving them unable to glow. >>> >>> I have a bag of dead nixies, mostly 5031/6844, took 2 out, and >>> microwaved them for 2 seconds. Got a brilliant crimson glow. One of them >>> shows some cathodes working, so now I have to go back thru the bag to make >>> sure I find the totally dead ones, or at least the ones that have glowing >>> only on the bondwires, and nuke them in the microwave oven. I have other >>> boxes for dying nixies, and so-so nixies, so I'm really surprised anything >>> in the "body-bag" of dead ones actually glowed. Unless perhaps the zap from >>> the microwave oven did something to the internal metal. >>> >>> I have some more experimenting to do. >>> >>> On Thursday, December 10, 2020 at 4:57:40 PM UTC-8 Chuck wrote: >>> >>>> Burroughs 6844A is domed not flat. I also have some National >>>> Electronics NL-6844A tubes. Frankly, I have had much better >>>> >>>> luck with the National Electronics brand. This recently purchased >>>> batch of (8) Burroughs 6844A tubes is a bad batch. >>>> >>>> The boxes all are stamped MAR 4 1968. The tubes themselves are >>>> date-coded 6750 F20. In white letters stenciled on the glass: >>>> >>>> "Burroughs 6844A NIXIE". >>>> >>>> >>>> >>>> The test I did was that the anode got connected to +170 volts DC >>>> through a 15k resistor. Then the digit cathodes were selectively >>>> >>>> grounded to the negative side of that power supply. On all (8) of >>>> these Burroughs tubes, most of what is seen is an intense glow concentrated >>>> >>>> around the tiny internal wires which connect the digit cathodes of the >>>> stack, to the pins. These tiny wires pass closely to the outside of the >>>> >>>> Anode casing which surrounds the digit stack. The glow strikes in the >>>> wrong place. The glow is around the lead wires instead of being >>>> >>>> around the digits. I am very confident from the way these tubes were >>>> in those boxes, that only one of the batch had even ever been out of the >>>> box. >>>> >>>> >>>> >>>> So I am curious what causes the glowing lead wires. >>>> >>>> >>>> >>>> Chuck >>>> >>> -- > 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 view this discussion on the web, visit > https://groups.google.com/d/msgid/neonixie-l/2f0a455d-a6ae-44bb-bc40-d5eeda5028d1n%40googlegroups.com > > <https://groups.google.com/d/msgid/neonixie-l/2f0a455d-a6ae-44bb-bc40-d5eeda5028d1n%40googlegroups.com?utm_medium=email&utm_source=footer> > . > -- 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 view this discussion on the web, visit https://groups.google.com/d/msgid/neonixie-l/292bdd1f-7359-48f9-aa03-4ee77774ae04n%40googlegroups.com.
