I may have an idea where the confusion comes from. RCA made two different
813's one with a graphite plate and the newer version with a metal plate.
There may be other internal differences between the older 813's and the new
newer ones. And the filament could be one of them.
73
Bill wa4lav
At 07:21 AM 5/29/2006 +0100, Steve Thompson wrote:
>Will Matney wrote:
> > Peter,
> >
> > While on the subject, you wouldn't know the approximate G1 input
> impedance would you? That is with the specified plate and grid voltages
> on the tube.
>
>If there's no grid current flowing, doesn't it just look like a
>capacitor for all normal purposes?
>
>Steve
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