Hi rkvs, Warm welcome to the world of nixies.
The darkening of the tube is part of the manufacturing process and is not an indicator these have been used. Shorter leads are also not an indicator, sometimes they are trimmed for shipping. In brief, its purpose is to clean impurities from the cathode electrode and gas. The front of the tube is also affected, but it has been partially shielded by the mesh-type anode. The very early and excellent-named 'tuneon' bargraph tube had no such mesh and look<http://www.radiomuseum.org/forumdata/users/14211/tuneon_brian_001_sml.png> at it before and after prolonged use. Alex I think you are referring to traditional 'flashed' getters that leave an unmistakable reflective surface on the glass. I believe the 'non-evaporable' type is used in the IN-9 and IN-13, in the form of a sintered metal alloy 'pill' at the very top of the tube. Here<https://dl.dropbox.com/u/21172615/DSC03812.JPG>is a close-up of that 'pill' at the top of the tube, showing the granular surface. For the getter to operate it must get warm/hot. The getter is also connected to the cathode which warms it up during operation. Here<https://dl.dropbox.com/u/21172615/DSC03813.JPG>is a close-up showing just this (apologies, it looked in focus on the camera). The thin wire is the end of the long cathode wire connected to the getter and stretched by bending that U-bracket. If you want to activate the getter without the tube on...place the tubes in an oven. There are plastic parts inside so don't overdo it. Bake for 1h until crispy but not brown. It is clear that your tubes have been left in storage for decades and therefore require cleaning of the impurities inside. The term for that is cathode cleaning by sputtering, or cathodic sputtering. Have a look at my post here for a method I use on IN-13s, same principles apply: https://groups.google.com/forum/?fromgroups=#!topic/neonixie-l/GAREG0tdVsI There are also a few comments on full-wave rectified or smoothed power supply. You can easily clean the tubes with your setup. Just change the resistor to 220 Ohms (to reduce the current to 200% of rated) and add an electrolytic tank capacitor after the rectifier to have a smooth DC supply. 47uF-470uF at 200-500V should do it. For a capacitor you can use the ones from an old PC power supply. Please use an appropriate voltage and be careful. Dont worry about the higher average voltage, the transistor will take care of that. Set your input to 5V and power on. Leave it for a couple of minutes. A 'dirty tube' will glow from some point on the bar and slowly fully illuminate. Others will be very close to the top and others at the top and very bright. Reduce the time for tubes that start at the top to say half. Once done safely discharge the capacitor. Good luck! Regards, Alex On Wednesday, March 13, 2013 4:39:45 PM UTC, rkvs wrote: > > I performed the test again after 10 minutes after posting the previous > message. I repeated Step #2 in Previous post again few times (using 150ohms > emitter resistance). > Now, the tube glow reached 100% i think. > > I changed back emitter resistor to 330ohms and glow is now 95% of full > length. I'm wondering why it didnt work when I performed step #2 some time > back? Will 10 minutes gap inbetween do the trick??? > > -- 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/msg/neonixie-l/-/FC6VLqHG0C0J. For more options, visit https://groups.google.com/groups/opt_out.
