Well,

I managed to get a nice 12Vtt square wave on 137kHz + all harmonics,
and used this to drive a single IRF530, just to see what happens.

Had to use a resistor to crank down the current, as my powersupply
couldn't handle it............

At least some interesting things happend......the filter coil get's
warm.....
well, I am not surprised as it is an T106-26 coil from a computer power
supply.
Also the 3mH coil in the DC-input line makes some nice noises........

All at 7V drainvoltage, and 1 Amp draincurrent.
Measured 30Vtt sinus over an 47Ohm resistor,
and around +30dBm, or 1 Watt over this same resistor.

Far from ideal, I know, but just want to get some experience and do some
tests starting with this very simple inefficient circuit.
I am sure I'll get more power in the future when using other types of
amplifiers.
I think the 12V squarewave unit can drive a lot of other stuff, like
multiple
FET's via transformers etc.

Now first need to build an bigger powersupply, a dummyload, and of course
al the coilstuff for the antenna............

A 100V/10A power supply will be the next to go for.........
Transformer is already there...............

Dick, pa4vhf