Jens, Should also have mentioned that the cathode should be about 0.25mm (about 0.010 inches) thick and about 0.4mm wide, which should give you a glow width of about 3mm (Dance, page 229) - cathodes should be spaced at 1mm. The anode is normally placed in the Faraday dark space (see Bylander ch 4, "Gas Discharge Fundamentals). With a pure Mo cathode and a 1% Ar Penning mixture (this is not too critical - between 1% & 3% seems fine), you should see strike voltages of about 130VDC. Sputtering depends heavily on the cathode material - pure Ni cathodes have a short life (low 100s of hours) - Ni/Fe is better, then Ni/Fe/Cr and finally Mo (much much better - far lower sputtering) - If you can't use Hg then go for Mo cathodes - the addition of Hg changes everything and pushes the life of the tube into the 1000s of hours. Have the cathodes laser-cut - far easier. Mo sheet can be bought on eBay for not too outrageous prices, e.g. item 400080303931 - USD 25 for a 6" x 6" sheet - enough for a lot of displays.
Note that you should try for the same current density on each cathode, i.e. if you want a single anode resistor, try to keep the surface area of each cathode approximately the same - this is generally done by subtly widening the stoke width of digits with a shorter linear length, e.g. the "1" digit is fatter (wider stroke width) than the "8". Much more on all this in the 3 standard works - Weston, Dance & Bylander. HTH Nick -- 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.
