Hi Phil,
If the voltage is really 8,25Veff then?your output is 1,4Watt, not 2,5Watt. That is a little low. How did you measure the voltage across the dummy load?
In my 20m QCX I used an oscilloscope (200MHz bandwidth) and measure around 46V peak-peak. That equals to 23/1,4142= 16,2Veff
If you do the math then the output is 5,3Watt.
73,
Martien PA4H
MartienPA4H