FvM, thankyou for pointing out the 19uH of leakage inductance for this pulse transformer.
I added this 19uH to the simulation, in series with the primary winding.
It really, really slows up the rise of the FET gate drive current. -It's horrendous, literally.
The power dissipation in this upper FET is thus considerably increased unfortunately.
Also, the FET gate charge current is so heavily filtered by the 19uH leakage inductance, that i end up being able to get away with using the 1N4148 diodes since the current doesn't get anywhere near above the 1N4148'S Max. current rating.
Also, i had to decrease R17 to 220R as this was needed to dampen the horrendous LC oscillation of the Gate voltage caused by the leakage inductance and the capacitance.
Does any reader know how anybody ever gets by using pulse transformers for high side FET drive?
-with the above said problems.