Total posts : 45366
The circuit feeding the external antenna jack does not have significant low-pass filtering and it is not tuned, so harmonics are to be expected. This is OK because once the coax is connected to the ATU and the ATU is properly tuned to resonance, the waveform should change to a sine wave and there won’t be significant radiated harmonics.
I have no explanation for why different people are seeing different power with their seemingly identical measurement method. There are too many possibilities to even speculate.
As Neil said previously in this thread, multiplying peak voltage by .707 to get RMS voltage only works for a pure sine wave. At the upper limit, for a pure square wave, the RMS voltage is equal to the peak voltage. The RMS voltage for a random distorted waveform can’t be determined unless you have some sort of RF voltage measuring instrument that displays true RMS voltage.