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Old 6th Jun 2008, 9:26 pm   #5
majoconz
Heptode
 
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Join Date: Jan 2008
Location: Ashhurst, Manawatu, New Zealand
Posts: 570
Default Re: Another (possibly silly) valve question

It's not the HT that makes the cathode emit electrons - just warm it up and off they go. The electrons emitted aren't pulled back to the cathode, they just wander around aimlessly. Perhaps they all pile up in the bottom of the valve and eventually short all the pins out........perhaps I'll think this through again.....I have heard of 'poisoned' cathodes but really don't know what they are, perhaps just lost their emissive coating.
Regards - Martin
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