28-09-2017, 04:04 PM
(28-09-2017, 03:16 PM)Murphyv310 Wrote: Hi.
The difference with mine is I use one grid as the crystal oscillator and the other one for AF input. The crystal is 1566 khz fundamental.
That does work, but much worse than how it's intended to work because the differential g1 volts steers the beam off the anode and only the common mode amplifies.
It's not remotely like a dual gate FET or any ordinary multigrid valve.
G1 is NORMALLY two plates either side of the filament at right angles to the two beams. So more negative "pinches" the beam. The 1j37b and 1j42a are identical filament and g1 construction to 1j24b, except the two plates have separate external connections. Thus any differential change, in EITHER direction is like electrostatic deflection and steers the beams off the anodes toward g2 (g2 current goes up). Only the common voltage on 1a and 1b changes the sum of Ia and Ig2.
Thus differential voltage steers from Anode to g2, which is why it's very good to vary gain of common mode g1a and g1b, or act as a full wave rectifier or frequency doubler.
Lots of circuits will "work". But proper application gives best performance.
