From Talking Electronics. I’m not sure if this circuit can be frequency modulated the full amount for the FM broadcast band. It’s difficult to push a crystal off its resonant frequency. I’ll be trying it someday if I can find the right xtal. I would be more inclined to instead use a ceramic resonator.
I have a few of Talking Electronics kits that I assembled and in general they work, but I would make some changes in their design.
https://www.talkingelectronics.com/projects/CrystalLockedBug/CrystalLockedBug-1.html
Below is the RF part of the circuit.
