Hi Rob,
These fluorescent light experiments have my interest! I have not played with these things at all - but sounds like you're getting results.
I've been reading BTHumble's posts as well.
A couple of questions. I have a reasonable understanding of 555 circuits and could set one up for let's say 15khz without much trouble. You're driving the xformer through the mosfet.
Where did the transformer come from? Did you rewind it - I see you're spec'ing 500 turns per layer for the secondary - how many layers are there?
Finally - I am guessing this circuit cold strikes the tube so no need for any special starting provisions?
Thanks!
Ted.