BTW, in the olden days we preferred 3x, 5x per stage. Two 3x stages would
give you 9x. The most brazen ones (not me) did a direct 7x or even 9x. We
just drove transistors in class C real hard.

Or today, many of us just overdrive an untuned MMIC amplifier and filter
out the unwanted harmonics...

Scott
N0EDV

And often have unwanted sometimes unfound parametric oscillations that have
nothing to do with harmonic content.

W4ZCB