Then why to tubes have a finite service life?
Maybe because the filament gets poisoned by gases...then
DC or AC won't matter.
Maybe because sustained emission degrades emission...then
DC will make a difference and reversing it will help distribute
the load.
Maybe because of temperature and trying to get emission
when the tube doesn't want to give it...then DC/AC won't
matter.
My understanding from CRT's and Tube lore tells me that
an emitter has a finite life based on how hard it's used. So,
I think DC/AC matters.
----- Original Message -----
From: "Bill Fuqua" <wlfuqu00@pop.uky.edu>
To: "jeff millar" <jeff@wa1hco.mv.com>; <amps@contesting.com>
Sent: Tuesday, October 31, 2000 8:41 PM
Subject: Re: [AMPS] DC Filaments???
>
> This is the same as saying the emission life is related to plate current.
> I think it is the filament temperature that determines the emission life
and
> that is no different for DC or AC.
> 73
> Bill wa4lav
>
>
> At 11:52 PM 10/31/00 -0500, you wrote:
>
> >A DC filament has a varying grid to filament voltage along its length
> >and so has uneven cathode to plate current along its length. Thus
> >in theory, one end runs out of emission life faster than the other.
>
> William L. Fuqua III , P.E. EE
> Department of Physics and Astronomy
> CP 177 Chemistry Physics Building
> University of KY
> Lexington, KY 40506-0055
> Phone 859 257-4155
>
>
> --
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