I think the fact that you do not have a load on the output tank, is what is
limiting the power output. Power tubes require a particular load Z to
deliver 'rated' power. Right now all I see is a parallel LC tank which will
be high Z. You quote a voltage of 50V "in the tank coil". How are you
measuring this?
Can you monitor plate current? If so, that times the applied plate voltage
will give you your DC input power. Power out will always be less than
this amount.
Also, are you sure your HV supply has the current capacity for the 200-400W
you want to get out? (This may mean something like 300-600W, or more, DC
input power).
Are you taking steps to prevent radiation of the generated RF into the wider
environment? The level of power you are talking can reek havoc with other
licensed users. The FCC could pay you a visit.
Finally, BE CAREFUL! These DC voltages can kill, and you have not lived
until you have gotten an RF burn from 100W, much less 300-400W.

Bob WB0POQ
wrote in message
oups.com...
Hi,

I am trying to build a tube power oscillator running at 25MHz from a
Russian tube (GI6B), and although I have it running, I can't seem to
ramp up the power to anywhere near the level I want out of it.