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Re: OLD Tubes/Coils - filament power (fwd)
---------- Forwarded message ----------
Date: Mon, 03 Mar 1997 17:54:09 EST
From: Mark S Graalman <wb8jkr-at-juno-dot-com>
To: tesla-at-pupman-dot-com
Subject: Re: OLD Tubes/Coils - filament power (fwd)
On Sun, 2 Mar 1997 22:29:49 -0700 (MST) Tesla List <tesla-at-pupman-dot-com>
writes:
>
>
>---------- Forwarded message ----------
>Date: Sun, 02 Mar 1997 16:59:06 -0800
>From: David Trimmell <dwt-at-efn-dot-org>
>To: Tesla List <tesla-at-pupman-dot-com>
>Subject: Re: OLD Tubes/Coils - filament power
>
> Hello,
>
> > *Never* operate tubes (at least those with thoriated heaters) with
>>less than their rated voltages and currents. Doing so will strip the
>>cathodes in short order. You may get lots of filament life with near
>>zero emission. Standard incandescent Light bulbs are a different
>story
>
>>entirely. The warning also applies to halogenated bulbs which will
>>have their lives shortened since the chemical processes in them rely
>>on running their at the high temperatures as far as I am aware.
>
>>Malcolm
>
>I was wondering if anyone knew if the 803's use a thoriated filament?
>I
>am using two 803's in parallel, with several turns on top of the
>1primary
>of the microwave transformer to get about 9.5 volts to power the
>filaments, since this arangement isn't curent limited, am I in danger
>of
>damaging these filaments?
>Thanks,
>
>David Trimmell
>
>
David, The 803 does have a thoriated tungsten filament. As far as I
know,
all directly heated cathode tubes are thoriated tungsten, the filament
itself is
the cathode.
Mark Graalman