Hi
I'm not much for forward converters but I played with your circuit a little today and discovered if I make all of the following changes:
1. Reduce the load current by changing the load resistor to, say, 1k.
2. Change the RUN/SS cap to 100n. (longer ramp time)
3. Insert a 37.5k resistor from the 3706 FS/Sync pin to ground (I think this changes the OSC Freq to 50khz)
4. add IC=0 to the spiceline field of C9.
5. Change the upper pulse transformer ratio to .6:1 (360uH|1mH)
6. Change the V1 source to PULSE (0 36 0 1u 1u)
whew...
Then the output eventually rises to about 32v then levels off.
Don't know what to make of this and I could be doing something silly, but I thought I'd share the info..
The simulation takes a heck of a long time..
I stopped it at 959.269 seconds...
See output graph attached.
eT