This is a generic class E amplifier I made with LTspice and I'm trying to get the perfect waveform at a reasonable voltage. I want to attach this to a real transmitter and be able to successfully transmit sound for at least a few hundred feet.

V2 here represents an ideal oscillator running at 400Mhz with 50% duty cycle. In the real circuit, V2 will be replaced with a basic FM transmitter and this circuit will be an extension to boost the signal.

V1 is a 5VDC regulated power source (from 7805 regulator)

The following are results I got when I used 25, 50, 100 and 200nH inductor and 50nH seemed to produce the greatest voltage, but is there some math I can use to calculate the perfect inductor because I don't want to constantly change values and hit the run button in LTspice.



and for simulation, I put a checkmark to the following:

- Start external DC supply voltages at 0V
- Skip initial operating point solution

Then I made it capture data from .00000202 seconds to .00000205 seconds because I assume intial conditions will be unstable.

So how do I calculate the perfect inductor value? Source frequency right now is 400Mhz but I might change it to either 433Mhz or 466Mhz.

 

The peak is probably the resonance of the inductor with the capacitance of the transistor.
Also, from a couple of datasheets for the 2N3904 I found ft = 270MHz or gain bandwidth product = 300MHz so i can't see it being much use at 400MHz.

 

The peak is probably the resonance of the inductor with the capacitance of the transistor.
Also, from a couple of datasheets for the 2N3904 I found ft = 270MHz or gain bandwidth product = 300MHz so i can't see it being much use at 400MHz.

True but LTspice doesn't come with the PN3563 transistor that I normally use for VHF, so I used 2n3904 here. How would I calculate the proper capacitance of the transistor here?

 

You can probably find a model for that transistor on www.

 

This is A CLASS amp. Distortions is normal for this circuit.