There was a spirited discussion some time ago about the cascode circuit, I forget the context. Anyway, I came across this schematic of the Johnson 250-39 TR switch and thought it was interesting. Cascode triodes, and the grid bias developed during cutoff is also coupled to the second triode. DC-wise, the two triodes are in parallel, ac-wise, it is a cascode. Note the choice of tubes, the 6BL7 is a vertical oscillator/output tube with a combined plate dissipation rating of 12 watts. The heater power alone for that tube is nearly 10 watts! Pretty sturdy for basically an RF preamplifier.