Sounds like a good excuse for a tube autopsy... If you are indeed over-driving the current then you'll be sputtering material off the cathode which after a while will have two effects. Firstly there will be some gradual darkening of the tube as the material deposits elsewhere. And secondly you'll see gross physical erosion of the cathode - you can see a similar effect on dekatron cathodes where the glow has been sitting stationary for a very long time (usually the zero cathode of the tubes making up the higher order decades of a multi-tube counter). Given that you describe a 'tink' noise, my guess is that the cathode has eroded to the point where it physically broke, perhaps under the thermal stress of being activated. Time for new tubes.
The Soviet datasheets only promise 1000 hour life for IN-9 - I can't find a similar overall guaranteed life specification for IN-13. My experience is that they will last much longer than that if not overdriven. With regard to the current required to achieve full scale, yes there's normally some cathode poisoning which needs to be burned off when you first fire up the tubes (worse on IN-9 than IN-13), but then they should settle down and operate at the specified sensitivity. The last centimetre or so of the cathode is difficult to illuminate even in a well 'oiled' tube - they lose linearity at the upper extreme. Best thing to do is not to worry about trying to light up this bit. 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 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/d11e0f79-e6f3-4657-83f8-1aed7fd14ede%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
