This is a really dumb question but it dawned on me that I did not know
the correct answer.

In terms of old transmitters from the 20s/30s...In a crystal oscillator
I understand the concept of setting the oscillator output tank to
favor the harmonic from the crystal. (Stop me if I'm wrong already...)

But in a doubling amplifier stage am I counting on having enough
harmonic content at the input or am I creating the harmonic with the
non-linearity of the amplifier?

TIA
-Bill WX4A