Crutschow thanks, I implemented your suggestions and its looking a whole lot better, in fact its looking darn near the excel plot that I calculated for it...the thing is, because of the 1e6 inductor, I can't simulate the thing in a valid way in the time domain ( ie transient analysis)
Also, I feel a bit aggrieved putting in 50v......I don't know why, its just that in the LT1243 controller, the maximum current that can flow out of the error amplifier output is 1mA.
-it is a bit offputting when you cant simulate something in the time domain due to components you have to put in to allow simulation in the frequency domain...I mean, I like to do the AC analysis, and that go to the time domain and do it at a spot frequency, and check it corresponds.