OK...sounds like time for another experiment: Swap with a non-contacted tube and see if the dot goes away in a few months....
BTW, the inside of the case is warmer than room-temp so the point where the tube contacts the glass cover will be cooler than the rest of the tube. The clock draws 14 watts, of which ~10 watts is just for the 6091 nixies and their drivers. -- 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 post to this group, send an email to [email protected]. To view this discussion on the web, visit https://groups.google.com/d/msgid/neonixie-l/0f2080d5-ef99-4112-aaf3-c89c337e56ea%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
