Indeed welcome Phill ! You are starting to slide down a very slippery slope indeed with the dekatron fascination. They are quite compelling tubes to play with, and the addiction gets worse if you start to collect the different flavours, look into the history etc. You're doomed mate. :)
On Friday, February 5, 2016 at 6:45:04 PM UTC, threeneurons wrote: > > All "high speeds" have a very high dud rate. I'm not sure if the gas in >> the "blue" ones is argon. I'm leaning towards hydrogen or helium. If its >> one of those two, then that would explain the high dud rate. Hydrogen will >> eventually react with the metal bits and form a hydride. Helium can >> actually diffuse thru solid glass. In either case, in time ... no gas, no >> glow. >> > > The hallmark of the fast dekatrons is hydrogen, first as a minority component of a gas mix in the 'mid-speed' tubes (say 10kHz upwards), and increasing in proportion generally as the max speed increases. The fastest tube types are just hydrogen. The bit of physics that limits the speed of glow-transfer is how fast you can deionise / de-energise the gas around the electrode that the glow just departed, and hydrogen acts as a quenching agent to speed this up. I've done quite some research into the dud problem, and I think I've pretty much convinced myself that it's bad chemistry rather than a physical leakage - will write up the arguments around this at some point. Having looked at a lot of different dekatrons (my research collection is north of 600 now - eek!), the dud problem is quite variable across manufacturers and specific tube models. The Elesta tubes are generally pretty good - they specialised in hydrogen fills and it seems knew how to get it right. At the other end of the scale the tube that wins the prize for being dead most often - the Norwegian Blue of the dekatron world - is the Mullard Z505S. You might see it marked under other brands of the Philips empire, but they're all made by Mullard at the Mitcham factory. And they're almost all dead now sadly. Cheers, Jon. -- 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/55be737d-bada-4169-91bd-7eff27798398%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
