The problem

the first one.
After the destruction of some resistors.
I was going to use AC for the heater.
16.5V 15Amps.
And I thought that there would be no 50Hz problem.
We all make mistakes.
There was an ENORMOUS 50Hz, well 100Hz actually.
So no AC.
A DC power supply.
Built one, heavy, lots of capacitors.
And fuses.
No good.
So now I'm waiting for a 100Kh switching power supply.
And on the diagram you can see the soft start.

Then there is the coupling.
DC, maybe beautiful, definitely doable but I need to burn another 100Watts or so to match the DC levels.
A capacitor, no.
I didn't like it from the beginning.
Ari told me why, and I'll stick with that.
Not a whole lot of other posibilities left...
An interstage transformer.
Jörg.
Waiting for that too.