GHZ spectrum analyser would be a nice bit of kit to borrow, but I dont
know anyone with one - which is a pity. The scope is 40MHz so 25MHz is
pretty close to its max and the resolution is not the best. Waveform
is fairly symmetrical so I think the fundemental is right at 25MHz.

Ill do the APC tonight, what difference will it make?

As for 1.5kV - yup, I have had it cranked to full, 2.2kV, and no extra
power really (maybe a slight amount, but I am looking for 1kv swing
where I am only seeing 50v so its not even close). Underwear got
messy... makes the hair on the back of my neck stand up from fear to
be that close to a 10u cap charged to 2.2kv...!


Also... borrow a GHz Spectrum Analyser and chech that the unit is
running at the expected freq. What bandwidth is your scope ?

An anode APC is also a very good idea. A few turn of 16AWG around a 2W
4R7 maybe a good start.

Any chance of cranking Va up to 1500V just to see how much power
increases ?

Don't forget a fresh change of underwear and a fire extiguisher