• 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.

PS Schematic Question

I recently saw this book being promoted here, and I can vouch that it is excellent in helping one get to grips with some of the concepts of thermionic emission and tubes in general. My problem has always been understanding plate resistance. I'm not all the way through the book, but I have a much better understanding of how chemistry, and the structure of the tube (spacings/alignments), dictate its behaviour.
Inside the vacuum tube
I have that book in pdf format and I'm reading it. This is what prompted me to question the schematic as it seemed counter to what I was reading, but I get it now.