If that were the cause, then I'd recommend a vigorous shake to remix the gases :) Seriously though, the contents of your tube are 98%+ neon, with the balance being argon and possibly a trace of mercury vapour. No air of any description in there, else it wouldn't glow at all under the voltage applied in your circuit.
More likely what you're looking at is a phenomenon called cathode poisoning, where tubes unused for a long time seem to pick up a surface contamination of some parts of the cathode which inhibits the glow. Try running the tube at 1.5 or 2x normal current for a while and see if that clears it up. Cheers, Jon. On Wednesday, April 2, 2014 10:56:43 AM UTC+1, Paul Parry wrote: > > I had another tube that for some reason the bottom half of the digit would > not light, is Neon lighter than air and just risen to the top of the tube? > > Cheers, > Paul > > -- 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/2c3faf17-8883-44ed-8cca-cc7fe1cacf77%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
