Simplistic MosFET HV Shunt Regs

[Salas]

Yes. You only need simulate a small bias preamp. It will do.

 

[merlin el mago]

OK thanks.

 

[merlin el mago]

Only gives 8.6Vout

 

[merlin el mago]

IRF840 is gone.

 

[Salas]

It does not work right with mod for HV it seems. At least in your test.

 

[merlin el mago]

OK thans anyway for kind help.

 

[merlin el mago]

Salas other SSHV2 without mod can't adjust the current from 8mA jumps to 50-60mA, can be damaged trimpot?

 

[Salas]

Yes, its likely.

 

[merlin el mago]

Changed, now works OK.

 

[Salas]

 

[merlin el mago]

 

[merlin el mago]

Salas sorry the OT, can I use the Jung mod for the #26 preamp with VR tube regulator?

 

[Salas]

Merlin, it seems HV sensitive in your up to now tests, don't know. Try only if you got enough DN2540s to spare in case of magic smoke again...

 

[merlin el mago]

Ok thanks

 

[merlin el mago]

Salas it serves for something Q5 always goes with CCS Jung mod, the strange thing is D1 doesn't go.

 

[Salas]

Could be the 1uF capacitor in the Jung mod slows the start up and leaves Q5 exposed to over voltage. Jung did not try or recommend for HV or in combination with a parallel thing so its not a general fault. Make that capacitor 10nF film. See if it may work in a final attempt since you like so much to try that mod in HV.

 

[merlin el mago]

OK I will try.

 

[merlin el mago]

One hour going on, load 20K, voltage across load max. 189Vout, voltage across 100R resistor between PSU and Jung mod is 3V = 30mA.

Can I connect the real load?

 

[Salas]

You made that cap small and it stayed well? That is good. Time to apply I guess.

 

[merlin el mago]

Doesn't work with real load, when powered Vout was 320V, tried to adjust with the trimmer but when arrived to 290V aprox dropped to 16V, tried to go up with the trimmer but Vout doesn't go up. Powered off and after 10 minutes powered again, same story Vout 320V tryign to adjust 16V, I taked off the two 10R of my CRCR PSU if wasn't enough curren but the issue continue.