I got a chance to crack open the case today. The supply voltage is 500v, the voltage at the anode is 162v. The voltage across the 1M current limiting resistor is 335v. The fluke 77's input impedence may have some affect in measuring the voltage across a 1% 1M resistor. I tried adding a 1% 10M resistor in parallel with the 1M resistor. The voltage across the combination was 334v. I did notice the glow covered more of the pin.
On Tuesday, May 3, 2016 at 9:07:20 PM UTC-4, Mike Mitchell wrote: > > The camera flash washed out the glow. The glow covers a bit more than 1/2 > the pin. I'm using A-101 dekatrons. > The power supply is a voltage tripler powered from the 120v mains. I have > a 22-ohm fusible resistor in series with the main, then the voltage > tripler. Each capacitor is 33uf, with a 6.8M bleed resistor in parallel. I > don't remember the exact resultant voltage, but I think it was right around > 500v. The anode current limiting resistor is 1M. That puts the cathode > current at 0.380 ma to 0.325 ma, assuming the HV ranges between 510V and > 495V and the tube's drop is between 130v and 170v. > > I should be safe decreasing the anode resistor to 910K, but 820K would be > too low. Next time I have the case open I'll measure the voltage drop > across the anode resistor (and the power supply voltage). > > > On Monday, May 2, 2016 at 12:09:32 PM UTC-4, Dekatron42 wrote: >> >> How much of the pins are glowing on your dekatrons? It looks like just >> the top portion is glowing on the first cathode in the photo. If only a >> small portion is glowing that will affect the wear of the pin. Also, what >> current are the cathodes run at? If a dekatron has been in storage for a >> long time, or if it has seen a lot of use the pins can be affected by >> cathode poisoning, they can be fixed by running them at high speed with a >> little bit higher current to get the shine to cover the pin fully. Some are >> hard to get to cover the pin fully but running them in the reverse >> direction (if possible) sometimes helps. >> >> /Martin >> > -- 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/4267ee41-4a0c-4b7f-9fdb-aefbfa566c31%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
