One of the best ways to learn about radios is to build your own, even in the age of cheap SDR dongles. [Aniss Oulhaci] demonstrates this with a simple HF SDR receiver built on a breadboard.

It may not be the radio station with all the hits and the best afternoon drive show ... Using his LNAs and filters and an SDR dongle, a reasonable 21-cm rig can be had for about $200 or so ...