[Amps] GS-35b 2 meter amp - plate capacitor spacing from tube?

[Bill Dzurilla]

Any Russian tube experts on this board?

Picked up a homebrew GS-35B 2 meter amp, seems to be working OK, about 650 watts out with 50 watts drive from my FT-847.  The anode is tuned with a piece of copper that is pushed closer to the tube or further away by a plunger controlled by a knob on the front panel.  Power was still going up when the plunger reached its maximum push on the copper, which leaves the copper about 3/4" (20mm) from the tube.  Do you think perhaps the plunger needs to be extended to get the copper closer to the tube for best output?  Plate voltage is 3300v, plate current only about .23 amps.

73, Bill NZ5N/OM9ACA