I got this circuit from a website and added an output filter to it. It outputs 30-35W of power. Even though it’s class-E, I measured the efficiency to be 71%. Where’s the inefficiency? I tuned the duty cycle so that the MOSFET would turn on at exactly the correct time, and it has a resistance of 90mOhms, so I don’t think it could be there, but the only other source of dissipation is the 10mOhms of the transformer windings, which is even less likely to be the main source of dissipation. Even when I make the MOSFET have zero resistance it still only has an efficiency of 77%.
