[Amps] QBL5-3500 VG2 regulation

[fgrisafi at tin.it (Fabio Grisafi (IT9GSF))]

Hello !
Do someone has a good schematic to provide a stabilized VG2 (with
protection) for a QBL5-3500 tethrode amplifier?
The voltage is +800V and IG2 will be no more than 100mA.
73 de Fabio, IT9GSF.

P.S.: I remember I have found a complete schematic of a QBL5-3500 amplifier
in the internet but now it is not accessible.