Yamaha Generator question

There is the possibility of running the 9180 with a 1000 watt generator if it's not an inverter generator. If the generator's voltage regulator is one that leads to an absurd waveform with a bad PF load, the PD's power draw will go way down. If the voltage regulator will let the output voltage sag significantly, the PD's power draw will go way down. This combination will find a balance point to operate continuously at a reduced convert output. It's the one advantage I can think of for PD converters needing a 120 volt good sine wave to achieve their spec'd output.