How Does a Class C Frequency Multiplier Work?

[skoomafiend]

This my basic understanding of it. I would appreciate if someone can correct me if I am wrong.

When a tank circuit at the output of a class C is tuned to the input signal, it energizes the tank signal on every cycle of the tank voltage. When you set it to a 2nd harmonic for example it energizes the tank signal on every other cycle.

OK, so in order to set it to a higher harmonic, you have to tune the tank. Which means you have to reduce the capacitance in the tank, so the resonant frequency increases to the next harmonic. So that would mean the capacitor would hold a smaller charge (reduced capacitance in the tank) and discharge faster? Pretty much fast enough to discharge and recharge twice (two cycles) before being re energized by the next input signal pulse?

Thanks!

 

[vk6kro]

When the signal passes through the frequency multiplier, it is deliberately distorted to generate harmonics.

Hopefully, one of these will have the frequency you want as output.

You then tune the output to this frequency and the other harmonics are largely rejected and the output is some multiple of the input frequency.

Driving a tuned circuit with a lower frequency to try to generate harmonics doesn't work. Tuned circuits behave more like filters than you may expect and less like, say, a pendulum or a tuning fork.