Bob: The Mallory book shows a Rider's reference of 3-26, but when I check my Rider's manuals, it shows the schematic with the 42 power tube. A check of my RCA tube manual shows that the 42 and the 2A5 have the same base, and it says both are electrically identical to a 6F6. Although the 42 and 2A5 aren't listed as substitutes for each other, I think the schematic should be good for either tube.
Steve
I should have said electrically identical except for the heater voltage of 2.5 for the 2A5 tube, so there must be a schematic difference since the 42 needs 6.3 volts on the heater. See Thomas' remarks on your other post.
Steve