Sam, can you put your hands on a VARIAC @ 1000VA (10A).
I use Variacs on all my home built power supplies. That will give you 100V
up to whatever you can get out of the supply.
You can even then not use a soft start circuit but if you are as impatience
as me when the DX calls, you better off with a soft start circuit.
In my experience you need minimum 2700 Volts (100 watts driving) up to
maximum of 3500 Volts ( 60 watts driving) in grounded grid with 4-1000A.
That should give 2 kilowatt PEP.
Why do you want to use 6 or 7 kilovolts ?
Good luck with the project.
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