[Amps] QB3-300 Amplifier

[DEHAYS Dominique]

Let's have a look at the ARRL handbook : vacuum tubes and semiconductors:
4-125 ( equivallent tube for QB3-300)
GG: max power is 145w withone  tube used in triode mode. Don't forget that 
in this mode you get no countrol of the screen and grid currents and that 
both are very high. Trying to run the tube at higher power ( like the 330w 
you can get in class C with G2 and G1 voltages applied) will make these 
currents very high ( exceeding by far the data sheet values) , so tube 
life will be reduced , and signal quality as well.
73's Dom/F6DRO