I dragged out Wayne's scope and a few meters to debunk a myth about
propane.
Someone was trying to tell me the output was less on propane than on
gasoline. I will admit it uses about 50% more by volume but for the
same output.
I used my convection oven for a load and that ended up being 5403
watts or around 98% of the rated output of the generator, a pretty
good test.
The wave form ended up being pretty "siney" although not perfect and
did not change with the fuel
http://gfretwell.com/propane%20project/Wave%20form.jpg
The rest of the test looked the same too.
http://gfretwell.com/propane%20project/On%20propane.jpg

I have that scope ready to go any time you want to drive to Estero
Wayne. For being 50 years old, it is still working pretty good.