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RE: - Re: OLD Tubes/Coils (fwd) - filament power (fwd)
---------- Forwarded message ----------
Date: Mon, 3 Mar 1997 09:29:43 +1200
From: Malcolm Watts <MALCOLM-at-directorate.wnp.ac.nz>
To: tesla-at-pupman-dot-com
Subject: RE: - Re: OLD Tubes/Coils (fwd) - filament power (fwd)
Whoa! I had to jump in and issue a warning here:
> Date: Sun, 2 Mar 97 06:07:24 UT
> From: William Noble <William_B_Noble-at-msn-dot-com>
> To: Tesla List <mod1-at-pupman-dot-com>
> Subject: RE: - Re: OLD Tubes/Coils (fwd) - filament power
>
> you said:
> Under-run the filament somewhat
> (say 10%) - the life will be greatly increased
> (I believe filament life goes as the inverse of
> the =fifth power= of the voltage if I remember
> correctly [maybe only the =fourth= -- it's
> a big factor] )
> [Bill] According to the GE light bulb book, it's the 13th power for lamp
> filaments (life/rated life to rated volts/applied volts), I don't see why
> tubes should be different. That makes your case even stronger
*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