In the earliest hobbiest versions surplus World War II VHF radios were modified to receive the 137 Mhz.
An analog converter with a timing circuit changed the audio into X-Y coordinates and send them to a scope. A Polaroid camera was aimed at the scope and set for a long exposure image. As the satellite passed overhead it would plot dots on the scope, but it wasn’t until the pass was over and you developed the film (anybody remember B&W Polaroid film and the fixative sticks?) that you would see whether or not you had successfully gotten an image.
Now it’s trivial – a VHF scanner with one of the crystals replaced with a capacitor to increase the bandwidth, a homebrew antenna made out of coat hangers, and a computer with a sound card.
