[Amps] Grounded grid 8122's

[Bill, W6WRT]

ORIGINAL MESSAGE:

On Wed, 22 Jul 2009 20:01:52 -0400, "Carl" <km1h at jeremy.mv.com> wrote:

>
>Grounded grid where the grids are at DC and RF ground is not the same as 
>applying DC voltages to those elements that are still grounded for RF. 
>Comparison examples would be GG 813's vs the THP HL1KA.
>
>The latter is called Super Cathode Driven for a reason that easily 
>differentiates it from a simple GG cathode drive.

REPLY:

I guess we will have to agree to disagree. In both circuits the drive is applied
to the cathode (or filament). As long as the grid and screen are maintained at a
steady  DC level, whether ground or some DC level,  and have zero RF applied,
the circuit function is identical - the cathode is driven, the grids are not.

As to the Super Cathode Driven circuit somehow being different from GG, The only
thing I see is the matter of DC bias. In terms of RF functioning, what exactly
is the difference?

73, Bill W6WRT