• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

Constructions of ShuGang's 211 and 805A

Is there a question here?
The main difference between the two tubes is the grid pitch (211 grid wires are almost twice as far apart per turn than the 805 grid wires) and the spacing between the grid and plate. the plate of the 211 is very close to its grid whereas the plate of the 805 is spaced considerably further from its grid.
Daniel