I know it seems like cheating.... but... consider a zener and TIP50
darlington.
--scott


Yes, using a series regulator is certainly a possibility.

With a current of up to 350 mA (average) and a voltage drop across the
regulator that cannot reasonably be lower than 250V, the power dissipated in the
regulator would be around 90W, which is not enormous but not negligible either.

However in my case I plan to obtain 1000VDC using a voltage doubler. So I could
use two separate series regulators on each of the two 500VDC arms of the supply.
This would probably make the design simpler.

73

Tony I0JX