Sixty years ago this month, the October 1955 issue of Popular Electronics carried the plans for this one-tube broadcast set. Even though it had only one tube, it was capable of driving a loudspeaker, thanks to the fact that the tube, a 1D8-GT, was actually three tubes in one. In consisted of a diode, which was the radio’s detector, a triode, which served as the first AF stage, and a power pentode which drove the speaker.
So even though the set used a single tube, it was the equivalent of a crystal set with two stages of audio. The article notes that the set gave good performance on strong local stations with just a few feet of wire for an antenna, and that it was able to pull in more distant stations with an outside antenna and ground.
A piece of wood, 8-1/2 by 5 inches, serves as the base, and the controls and speaker are mounted in place with right-angle brass brackets. Terminal strips are used for the battery, antenna, and ground connections.