[Patrick Turner]

flipper wrote:

Ok, screen to plate, no sweat.

The question is, with a pentode that has separate cathode and
suppressor connections, is connecting the suppressor to cathode the
best thing? Or leave it float? Would there be any operational
difference?

I'm thinking of the 6GK6, which has the added confusion that it says
'internal shield' is connected to the suppressor.

Suppressor can be connected to anode or cathode without much difference.
With pentoded triodes the suppressor doesn't have much to do because
there isn't much to suppress; the secondary emission becomes a problem
in tetrodes when Ea drops well below Eg2, and electrons bounce back from
the anode to the
screen, as if having second thoughts about a nice juicy positive target
to hit.
But while the screen is tied to anode the secondary emission isn't a
problem.
Some tubes have a fair amount of suppressor transconductance, 6DT6 for
example.

But try it either way and measure gain and examine the wave for
distortion and stability.

Patrick Turner.