SB-200 issues - balanced finals.

[Kenneth G. Gordon]

On 7 Jun 2007 at 21:27, Wilson Lamb wrote:

> Did you try running the tubes one at a time??

Yes.

> I don't understand about the series resonance with the grid caps and I
> don't have the schematic, but they could only be resonant at one
> frequency.

Or a fairly broad range of frequencies. They are pretty low "Q".

>  If they were series resonant, they would short the grid to
> ground for RF, wouldn't they?

Yes. That is what they are SUPPOSED to do. This is a grounded-grid 
amp. Those caps ground the grid for RF AND help reduce the chance 
of VHF parasitcs.

>  If they are grid to ground, I'd guess
> they are meant to short out high frequency energy to ground to kill
> parasitics.

Yes, partially.

> Has anyone tried running 811s in one of these amps?

Not me.

Ken W7EKB

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