Years ago I got a 6476 dekatron that would not "un-stick" at normal operating current (~350uA). One old tried-and-true method for curing "cathode poisoning" type ills, is to run the part at higher currents for a while, to burn the crud off. I tried it with this tube. At 2mA (2000uA; 6x normal), it would step properly. But every time that I'd lower it back down to normal current, it would stick again. I'd increase the "burn off" time (of higher current operation), to hours, days, months. The result was the same. Step okay at 2mA, but stick anything less, let alone 350uA.
Today, however, was different. I just got a new 6476 tube that needed a quick test. The jig used for testing had that offending tube still in it. Running at 2mA, for probably over 2 years. Before unplugging the "bad" tube, I pulled the jumper to decrease the anode current to ~350uA. I expected the "bad" tube to stick, but it continued to step normally !!!!! The glow area shrank, indicating that the current dropped, as intended. But it stepped properly !!! Here's a video of the jig, working: http://www.dailymotion.com/video/xemsv6_dekatron-pendulum-gc10-2p-smallest_tech The video features the GC10/2P, but the offending 6476 is standing there right next to it, stepping at the incorrect current of 2mA. Notice how the whole cathode rod is illuminated. Normally, only the top quarter, or 3rd, is glowing. Moral of the story ... I will unstick, eventually. BTW: Newly received Ratheon CK6476 runs just fine, though it is used, due to a small portion of the top dome showing a little excess silvering. -- You received this message because you are subscribed to the Google Groups "neonixie-l" group. To post to this group, send an email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/neonixie-l?hl=en-GB.
