[Johnson] Grid Saturation In AM Transmitters

[radioman]

Grid saturation is a requirment for steady plate current and postive
modulation in plate modulated AM transmitters. Which is why reducing
drive is not an option for power control.

Look at the old ARRL handbooks (50's and 60's)... and you will see the
list of common AM modulation problems..

Downward Modulation ?  low grid drive or poor loading
Unsteady Plate Current ... low grid drive.


At minimum, you must run your grid drive at least high enough so that
increasing the grid drive wont cause the Power output of the final to
increase... usually the stated figure is somewhat higher.

Reduction of grid drive.. while running AM... is just a recipie for very
bad modulation, either with negative modulation, carrier shift.. or
both.

Drive reduction works great on those grounded grid linear amps.. common
to ssb,
but not in grid driven plate modulated amps running Class C.

Larry