I picked up a used Xantrex Xpower 1000 inverter. Typical 12V to 115 Vac @ 1000 W modified square wave inverter.
Everything seems to be working, but I noticed one odd thing. When it warms up enough for the fan to kick in, the waveform changes; the non-zero part of the modified square wave gets slightly shorter and the zero time gets longer so the frequency doesn't change. A scope shows that the peak voltage isn't changing. A non-true RMS DMM shows the change as a significant voltage drop from 120V to 110V. The output voltage is speced at 115 Vac +-5% so both 120V and 110V are within spec.
This is the first time I've played with anything like this. Does this sound like normal behaviour?
Thanks,
Ed