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Old 08-14-2012, 11:58 PM
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citfta citfta is offline
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Hi Graham,

Thanks for the very interesting links. I just finished reading the rest of the Perreault paper. I have to say all of what he says does make sense. I know that the tungsten welding electrodes are supposed to be thoriated. I wonder if we could use them to make our own ion generator? Some time ago I read that someone thought the E. V. Gray circuit would work like it was supposed to have worked if it had a tungsten welding rod in the tube.

Originally Posted by GSM View Post

The secret within those early thermionic tubes were filaments of thoriated tungsten used by manufacturers competing for efficiency per directly heated filament Watt.

A thoriated tungsten cathode can be induced to release additional electrons if it is bombarded with a lesser electron stream attracted from an anode via a positive grid potential. If the tube is oscillated, then those additional cathode released electrons may be conducted away, again via the grid w.r.t. the anode.

Do please take a look at the TH Moray tube circuits,
also page 37 here >

There was a very recent video of someone doing this on YT, but I did not retain a link, and modern indirectly heated cathode tubes, even thoria coated types, would likely succumb to ion poisoning in a way which early thoriated wire heated types were not susceptible.

Cheers ............ Graham.
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