[Boatanchors] [Milsurplus] Bad Nixie Tube?

[W2HX]

They definitely go bad. Quite often they experience what is called "cathode poisoning" for more info, see this:
http://www.tube-tester.com/sites/nixie/different/cathode%20poisoning/cathode-poisoning.htm

but some HP counters that use nixies actually also use small neon bulbs (I forget which) with a little light sensor to decode their odd BCD inside the counter for display on the Nixie tube.

Below is an excerpt from http://www.melamed.org/clock.htm

"HP designers found a way to isolate the high voltage from the (lower) logic voltages. ... They illuminate an array of photocells (the circles near the top of the schematic) in combinations of 3; the cells are arranged so that a given combination of three corresponds to exactly one filament (digit). (The little black squares on the schematic show, as an example, which lamps are lighted to produce zero on the display--four "0" bits illuminating three series-connected photocells that ignite the zero in the Nixie tube.)"

These nixies often go bad after so many years. Either of these could be your problem.

73 Eugene W2HX

-----Original Message-----
From: Milsurplus [mailto:milsurplus-bounces at mailman.qth.net] On Behalf Of Don Merz via Milsurplus
Sent: Saturday, September 13, 2014 10:20 AM
To: MilSurplus QSLNet; Boatanchors Mailman. Qth. Net
Subject: [Milsurplus] Bad Nixie Tube?

Has anyone ever seen one go bad? I have an old Nixe HP counter that works perfectly and I'd like to keep it that way. Should I be keeping spare nixies? Or is that a waste?
73 de N3RHT 
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