Um, much more than any wattmeter's reading, I would be concered that it passes the "Twin Peaks" test.
The final-stage Plate Tune, the right-hand knob of the top pair, has no physical end-of-travel. The Load control on the left will turn only 180 degrees, then CLANG!, it runs into an end-stop. The Tune control on the right has no such mechanicl end stop on it.
Likewise the lower-left Driver Tune knob is this way, too.
BOTH of these knobs should show TWO peaks on the meter in ONE FULL TURN of the knob.
Those two separate peaks may be on opposite sides, 180 apart, or they may be right next to one another.
What matters is that the upper-right Final Plate Tune. AND the lower-left Driver Tune should EACH show TWO peaks in one full turn of the knob.
It's late. I'm gonna skip explaining why this matters. But if you see only ONE peak in that full turn, it isn't really a peak. It's the control reaching the end of its travel, before reaching a peak. Looks like one on the meter, but it isn't, really.
If either knob flunks the Twin Peaks test, you'll next need to know at which extreme the knob that flunked came to rest.
A Tune control with only one peak will be at one of two positions.
1) Plates all the way apart. This is the control's minimum setting.
2) Plates meshed together as close as they will go. This is "Max" capacitance.
Gotta know which it is, to correct the outptut coil on that control.
Any time tubes are changed, there's the risk the Tune control for that set of tubes won't peak like it did with the OLD set of tubes. Running the tubes unintentionally out of tune causes the same stress on the tubes as if you did it on purpose. They last longer if both Plate Tune knobs are "peaked" to a real resonant peak.
73
