Hank wrote:

Scott, you need a power pentode with a separate supressor terminal.
RCA made one: 6AG7. Overall, similar characteristics to a 50L6, but a
pentode, not a beam tetrode.

Makes sense. I want to do it on a low level stage though, so a 6AG5 is
probably a bit much. I was thinking something like the 6AU6 which also
brings each grid out individually.

You're on your own working out the Gm and Mu curves for G2 and G3.
RCA came up with the tube, along with the 1851,1852,and 1853, for prewar
TV video amplification.

Yeah, I noticed that the curves in the HB-3 are not really laid out for
such a thing.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."