Complexic and confuzzling circuits these are. I ought to look into that feedback loop design. Just imagine trying to stuff an EF86 into the same space as a FET hihi.
I looked on LabGuy's website, and he has some schematic for an (ancient) old video camera built by RCA. It used 7 6AG5 tubes for the video amplifier chain, and a double diode (I think) for the DC restoration. I'm gonna have to suck as much gain out of my tubes as possible.
Links:
https://www.labguysworld.com/RCA_PH-...estoration.htm
Shielding is also an issue. The only thing I have for that is... the great... the unstoppable... the magnificent... ALUMINUM FOIL! If I remember, Labguy just lined his 5527 iconoscope tube with foil, and it helped shield it. He also had a bad FET for the preamp in his home-made camera.
Links:
https://www.labguysworld.com/Iconosc...roject_001.htm