So, I now have a quantity of ten 4P1Ltubes newly arrived.... Not from Russia, but from Malaga, Spain. And a lot of questions to ask
So far I haven't found any detailed operating characteristics of these tubes, just two different very "generic" and not-too-informative mini-data sheets, both of which are from Russia, though in English language. .
It appears that VA = 150VDC, IA = 50 mA and approx. -8.5V control grid bias, is nominal operation, into a 4.5K plate load.
What is the specification for triode strapped operation, as far as internal plate resistance, transconductance and voltage gain?
If I were to triode strap these, I presume that the usual G2 connected through a 100 ohm resistor to the plate would be good. Should the 3rd grid be connected to the filament CT or ground, or directly to the plate? Update- it connects to the plate trough a resistor, same as for the screen grid.
Plan B would be to operate these in Class AB1 Push-pull, not sure of the best OPT A-A impedance to use for this application, I would SWAG 8K A-A, or should it be lower, perhaps 4.3K A-A, or even 3.3K A-A, or perhaps higher - 9 to 10K A-A ? Just considering OPTs that I already have available...
Just pondering another "weird tube" amp project...
УНИВЕРСАЛ ТЕХНО-КОНТРОЛЬ/ed B