[Boatanchors] 812 vs 811 Transmitting Tubes

[Ian Wilson]

One consequence of the difference in mu is that the 811 will operate
with zero bias (up to about 1.5kV if I recall correctly), while the 812
requires grid bias.

I think that the power gain of a grounded grid stage is influenced by
mu also.

73, ian K3IMW

On 5/28/08, GGLL <nagato at arnet.com.ar> wrote:
>        Yes, nearly identical, except 812 types are low mu (29)triodes,
> whilst 811 types are high mu (160) triodes.
>        812 are best suited for class C operation, while 811's are best for
> linear amplifiers (RF or audio).
>
> Reagrds
> Guillermo - LU8EYW.
>
> David Hollander escribió:
> > Looking at the data sheets, the 811 and 812 look to be nearly identical.
> >
> > Can you replace 811's with 812's in an amp such as a 30L-1 or any other
> amps that use 811's?
> >
> > Any comments?
> >
> > 73 es Tnx,
> >
> > Dave N7RK
> >
> >
> _______________________________________________
>