Farnell 352C 1GHz Spectrum analyser

[ppppenguin]

The OP can't post even a small section of the circuit here because it's heavily watermarked "Radiomuseum". I've sketched the relevant part.  The design can source current into G2 but can't sink any. I suppose a small current could be coming out of G2, so a resistor to 0V would be needed to stop the voltage drifting too high. It says 330V on the circuit.

I wonder why there's an extra diode in the feed to G2. I can't see what good it's doing. If it were not there, the focus pot would provide the necessary sink.

I still don't believe it's a 220M resistor.