When I got my 1st CK722 transistor in about 1954, finding applications was mostly limited to print publications like Popular Electronics or CQ Magazine and even QST.
Today with the Internet, at 5AM while munching on my oatmeal it is amazing what can be found. Following the Ted Henry Little Argonaut cited yesterday, I searched for Pencil Tube Receivers, and this is what showed up.
https://www.pa3esy.nl/zelfbouw/penciltube-rx/html/pencilM_set.html
A pencil tube radio from PA3ESY as found on the internet.
A Rig ready for SOTA or POTA ops.
This is not unlike finding some circuits for the CK722 and the itch to build something with pencil tubes.
73's
Pete N6QW
