Re: [neonixie-l] An odd, but interesting observation of a weak B7971 tube

[Nicholas Stock]

I've noticed a few 7971's needing a couple of hours to fully illuminate after which they're apparently very happy in the long term if in operation. Is this sign of a very small leak or something else? I'm not sure what to make of the 'gassy' term to be honest....were 7971's doped with Hg? Nick Sent from my iPhone On Oct 8, 2023, at 10:42, Paul Andrews <p...@nixies.us> wrote:  I’ve had some of these tubes that require a higher than normal voltage to even trigger. Most people drive nixies at 170V, but this can be a marginal trigger voltage for some tubes and completely insufficient for others such as the GR10G https://www.nixies.us/bwg_gallery/gr10g/ Shining light on a tube ionizes the gas inside, the brighter the light, the more ions. Tubes used in dark environments can take longer to light up. Once they are lit, the number of free ions in the gas is usually enough to keep it going. Several approaches were used to circumvent this. Some tubes have an extra cathode driven with a very low current that is always on. Some tubes were doped with Krypton 85, a radioactive gas, e.g. https://www.nixies.us/bwg_gallery/122p224/ On Sunday, October 8, 2023 at 12:13:47 PM UTC-4 gregebert wrote: Can you do some bench-testing to see if the segments fully light with a bit more voltage ? I collected current-voltage (I-V) data on all my 7971's so I can check them for aging effects. On Sunday, October 8, 2023 at 6:01:55 AM UTC-7 guus.a...@wolmail.nl wrote: Hello Jim,   If you have a source of UV-light, that will do a good job. Maybe an UV-Led beneath the tube will do the trick....   BR/ Guus Op 07-10-2023 19:26 CEST schreef Jim KO5V <jr...@earthlink.net>:     I have a B7971 that doesn't want to light up - the ends of some segments will glow,  but none will illuminate along their entire length. I have had tubes in the past that were probably a bit gassy, and they cleaned up after running for a few minutes to a few hours.   So, I put it into the "10 second" position of my Mod 6 clock, and ran it over night with no improvement. However after I had been up an hour or so, I noticed that the tube's segments were lighting up along about 3/4 of their lengths, and also that the low morning sun was shining on the clock. This state lasted for as long as the sunlight was on the tube - sometime after light moved off of the clock, the tube went back to it's wounded state.    This morning I watched as the sunlight moved toward the clock, and as soon as the light hit the clock, the tube immediately recovered, and performed like it did yesterday. However, that state lasted for about 3-1/2 hours after the sunlight moved away. I then shined a flashlight on the tube, and it recovered as long as the light was there.    I guess this is some kind of photo-voltaic effect. I have a bit of education in basic physics (for engineering), and this baffles me - but it's cool!   I have a reading lamp that puts out a full spectrum, so I will put that on the clock today and see what happens. I may also set up a test to run the tube at a bit higher voltage (180-ish V). It may never recover completely, but I think this is a fun exercise.   Anyway, and ideas are welcome. I may not be able to save the tube, but I might actually learn something.  Thanks.  Jim   -- 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+...@googlegroups.com. To view this discussion on the web, visit https://groups.google.com/d/msgid/neonixie-l/d2784c4a-c76f-4ae6-b0b1-86f14185bb22n%40googlegroups.com. -- 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 view this discussion on the web, visit https://groups.google.com/d/msgid/neonixie-l/84ecf40e-cfbd-4d8b-a287-8be443d1cf08n%40googlegroups.com. -- 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 view this discussion on the web, visit https://groups.google.com/d/msgid/neonixie-l/A2B96120-7BE5-46F4-859B-01C0715D6D8D%40gmail.com.