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Re: OLD Tubes/Coils - filament power (fwd)
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To: tesla-at-poodle.pupman-dot-com
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Subject: Re: OLD Tubes/Coils - filament power (fwd)
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From: Tesla List <tesla-at-stic-dot-net>
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Date: Thu, 06 Mar 1997 00:03:18 -0600
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Approved: tesla-at-stic-dot-net
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References: <199703050307.TAA17992-at-alumni.caltech.edu>
Edward V. Phillips wrote:
>
> Re:
> "As far as I
> know,
> all directly heated cathode tubes are thoriated tungsten, the filament
> itself is
> the cathode."
> Negative. Lots of rectifier tubes (5R4G, for instance)
> have oxide coated cathose (glow a dull red at rated voltage) and
> some very high power and/or very high voltage tubes still use
> pure tungsten, which is very rugged and requires very much
> higher operating temperatures than thoriated tungsten.
> Ed