More follow-up. Voltages are all approximately what is shown in the K7AGE table for the Q13-15 devices, slightly less as I have 11.5v out of a regulator to the main board. I bypassed the regulator and ran the main board off the incoming supply, about 13.5v, and no real change other than some voltages were slightly higher. I checked in to a 40m net with a station about 450 miles away, and there is no observable difference between "high" power and standard power, confirming that "high" is only a couple of watts lower. He commented that the audio sounded good (I have made the VK3YE type of mod, ending up with 30pf).? I also have a 100pf NPO cap across L7, but I don't see how that should change things.
Truly a puzzle.
=Vic=
Vic WA4THR