> On May 21, 2023, at 7:20 PM, Audrey <[email protected]> wrote: > > Isnt that usually only the case with vacuum tubes? I think you're thinking of > thoriated heaters
I leave it to someone else to come up with a definitive answer but a neon sign can start cold because the cathodes are coated with the stuff. I can't remember precisely what is used but it's more than just thorium. I'm not sure if they're all elemental but they might be. It's been a very long time. Part of precessing a new tube is heating the cathodes to reduce the oxidized chemicals back to their "raw" state. If a tube needs to be repaired and the tubing itself can be reused new cathodes will have to be spliced on and the entire assembly re-processed. Terry Bowman, KA4HJH "The Mac Doctor" https://www.astarcloseup.com "I’ve seen things you people wouldn’t believe. Attack ships on fire off the shoulder of Orion. I watched c-beams glitter in the dark near Tannhäuser Gate. "All those moments will be lost in time like tears in the rain. "Time to die"— Roy Batty, Blade Runner -- 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 view this discussion on the web, visit https://groups.google.com/d/msgid/neonixie-l/A79A9EBD-502D-447C-A3A1-46DFB156BE0B%40gmail.com.
