[Milsurplus] MOSFET High Voltage Regulator Circuit

[Mack]

Merry Christmas!

I've almost completed my ARC-5 transmitter/receiver project but I have a small amount of chirp when keying. I've confirmed it's the 200V I'm feeding  to the oscillator plate not being stable. I can eliminate the chirp by using my regulated bench HV supply.

Please help with with a link or send me a schematic for a MOSFET HV regulator that would work at 200V. I've looked about eight hours on Google and nothing fruitful has developed. I'm looking for a simple circuit with few parts. For example, could I just take a HV Power MOSFET and bias the gate with two 100 volt zener diodes in series? The trouble is I don't have a lot of experience designing with MOSFETS and I'm really out of my league. I even tried SPICE but after two hours made only a little progress with this complex program.

The T-22 oscillator plate is 200V at 20 ma and it is only applied when the code key is pressed and a relay is closed. The input to the regulator circuit is the B+ for the plates of the 1625's at 550-600 VDC. Therefore I need to drop from 600 VDC to 200 VDC at 20 ma and have reasonable regulation. 

I know a much simpler and perhaps more authentic solution would be to have two OC3's in series with an appropriate dropping resistor. However, I may at some point want to have a circuit for higher regulated voltages. I would also like to minimize the use of high wattage resistors in the power supply with the resultant heat.

Thanks as always for everyone's help. I'm really stuck on this one. BTW, I restuffed all the bathtub caps in the transmitter and receiver and you can barely notice they're not the originals. I'll post pictures of everything once I'm finished. 

73,

Mack de WB4MAK
www.nfarl.org
www.sedxc.org