Hey everyone! I'm diving into my first QRP homebrew project - trying to build a simple 20m CW transceiver based on some circuit ideas I found online. I'm struggling with getting the Class E power amplifier stage working efficiently. Class E amplifiers are supposed to be incredibly efficient but are difficult to get right. My calculations show it should work, but I'm only getting about 60% efficiency instead of the theoretical 90%+.

Has anyone built a successful Class E PA for QRP? What are the most common mistakes beginners make? I'm using a 2N7000 MOSFET and trying to get about 2-3 watts out on 14 MHz. Any tips on component selection or layout would be much appreciated!

Class E can be tricky! The key is getting the component values exactly right and keeping the layout tight. I'd recommend using Bill Slade's design notes and calculator spreadsheet - they're excellent resources. Also make sure your driver stage can properly switch the MOSFET with sharp rise/fall times.

I went through the same struggle on my first Class E build. Start with a simple Class C amplifier first to get comfortable with RF construction techniques. Class E is definitely advanced territory - maybe save it for your second or third QRP project?

Don't give up! Circuit design is all about experimenting with methods that work for you and that you can understand. Try building it on copper clad board first to minimize parasitics. The switching waveform at the drain is critical - scope it if you can.