Yet if he can’t find the part he’s after a Varactor may be a good solution. In this capacitance range, by “Varactor” I mean one or two 2N3904 collector-base junctions in parallel, nothing exotic.

 

Yet if he can’t find the part he’s after a Varactor may be a good solution. In this capacitance range, by “Varactor” I mean one or two 2N3904 collector-base junctions in parallel, nothing exotic.

How is a varactor a suitable replacement for a manually adjusted small capacitor that is intended to be set and then left alone? Air variables are noted for being very stable and having a quite high "Q" factor. Biased diode junctions not so much.

 

Depends upon the details of the application. I have used diodes as variable capacitors for decades and they have worked fine. Argue if you want, I know of my experience.