The vacuum tube was a necessary part of early radios, used to create and amplify an electric signal necessary for the radio to work. These were first made en masse about 1914, and companies like Philco, Sylvania, Westinghouse, and RCA soon became some of the biggest tube manufacturers. Collectors today look for antique and vintage vacuum tubes in working condition, as well as those made by the more famous manufacturers. Other key antique and vintage radio parts include knobs, switches, handles, and housing legs.