So far I have aquired some components. I ordered a high-voltage transformator with the following data:

- prim 230V/22A one phase
- sec two equal windings with taps for 800-900-1000-1100-1200-1300-1400V each winding capable to 1.8A. 

These windings can be connected in parallell or serie giving rectified voltages in steps between about 1100 - 4000V.
There will be four meters on the frontpanel: anode voltage, cathode current, grid current and heater voltage.
The pi-filter will be tuned by stepping motors and manually.
There will be vacuum realys for tx/rx functions.
The heating will be successively rised from 0V to 26V in about 2 minutes. After that the high-voltage will be switched on. Without heater the anode voltage cannot be switched on under any circumstansies. After switching off, the cooling fan for the tube will remain running until the tube is cooled off.
As the output impedance of the tube is quite low, there will be a need for capacitors across the tuning capacitors. I still haven't decided how these will be switched in and out. Relais? Manual switches?

Here are pictures of the full-wave rectifier and the filtering capacitors. Both are built on Euro 160x100mm printed circuit cards.

I received the tube and the vacuum capacitors from Russia. The capacitors are BIG, really BIG,  500pF and 1000pF, both 10kV design. Here are pictures of them. The pen leaning on the 1000pF capacitor is a normal ballpoint pen

Here are pictures of a broken 500pF 10kV vacuum capacitor. At last I learned how they are built and working :) Before I didn't understood how the vacuum was kept inside the glass. Now I am so much wiser...