Young Richard Feynman repaired radios in an early job. The work was more than a way to earn money: it gave him a practical setting in which to diagnose complicated machines and reason from effects back to causes.
Feynman became fascinated by radios as a child and maintained an experimental laboratory at home. In accounts of his youth, he would often approach a malfunction theoretically, trying to understand what must be happening inside the set rather than merely replacing parts at random. That habit anticipated the style of physical reasoning for which he later became famous.
The radio work is sometimes confused with other hands-on repair trades, such as fixing clocks, cameras, or bicycles, but those are not the household devices associated with this early Feynman story. His childhood experiments also included building a burglar alarm while his parents were away.
The episode helps explain why biographies portray Feynman as both an abstract thinker and an inveterate tinkerer. Before his work in quantum electrodynamics, particle physics, and the Manhattan Project, he was already learning to combine observation, mechanism, and bold practical experimentation.