Ham radio grew out of the early days of radio telegraphy in the first decade of the 20th century, when amateur radio operators shared the airwaves with the governments and ships communicating to colleagues on shore. Back then, signals produced by amateur radio signals were powerful enough to cancel out official communications; when this happened, the amateurs would be referred to derisively as “hams” for their clumsiness. The term was unwittingly embraced by the amateurs and it soon lost its negative connotation and also came to describe the radios themselves.

Since the end of World War I, hams have communicated on specific frequencies designated for use by amateurs. The first hams used radios made by Hammarlund, E.F. Johnson, the National Radio Company, and Hallicrafters, as well as kits sold by Heathkit and others. Radio sets made with vacuum tubes are known as glowbugs for the way in which the tubes on top of the sets glow. Ham radio components include receivers, transmitters, speakers, and handsets, which resemble those used on telephones.