What to do with a CK722 in 2024?

[old_coot88]

You'd also need to bias the base to bring the transistor into conduction (think grid of a triode by analogy). Run a resistor from the negative supply to the base. I'd start with maybe 22K and then go up or down as needed.

Built a few of these back around '58, using the '722's predecessor, the CK718. Anybody 'member the CK768, the first hobby grade RF transistor? Built a cute little regen set with it.

The 718s were "pulls" from hearing aids, evidently for excessive 'white noise', then offered in Popular Electronics for us nerds.