[pkolaczk]

If you can afford losing a bit of frequency stability, you can use a varicap instead and control it by voltage. Precise multiturn potentiometers are much cheaper. Or just buy a programmable clock signal generator based on PLL and then make it into a superhet (you can still have analog filtering and detection, but digital frequency synthesis so it can look more like a modern radio with frequency display).

There are so many options and all are very cool to explore.

[jacquesm]

Yes, varicaps are good and there are even varicaps with very large capacitance swings exactly for this purpose.

But it does require a very steady voltage and many more parts than just a single passive to not accidentally load the resonant circuit to the point that it becomes ineffective. You need to de-couple considerably to make this work, especially without injecting (phase) noise. And frequency stability and phase noise can be extremely annoying in particular applications.

[pkolaczk]

That’s why you probably want to use it in an oscillator rather than a filter. Then some of those problems go away. Although, some new ones appear like having to add a mixer … Some time ago I thought making a double superhet would be too complex but apparently it turned out quite a nice DYI project.

[hasheddan]

> There are so many options and all are very cool to explore.

Very much agree, controlling a varicap via an MCU is a nice intermediate step of "digital tuning" without going all the way to SDR.