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.