Best thing to do is gather data for several tubes, and plot it. Inconsistent data suggests problems with the tubes; maybe they are used, out-of-spec, reject, etc units.
I would use a voltmeter and measure the voltage at the following locations, while adjusting Vc to obtain (a) First speckle of light on the tube, (b) 25%, (c) 50%, (d) 75%, (e) maximum, which might not be 100%. Measure Vc, Voltage at emitter, voltage at collector, voltage at the AUX pin, AND the +120V supply (it may not be constant, due to loading). Obviously you would enter this data into a spreadsheet because there are calculations that need to be done (tube voltage and current), and it does a good job creating plots. Once you have that info, we can figure out what's going on. Is the transistor getting warm ? Depending upon the case style it may only be capable of 625mW. From the circuit, I can see scenarios where you could exceed this if you're running at 160V and above 13mA. -- 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/b6cbe906-453b-4e5b-8062-2c80848ba8df%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
