for a small line of Westinghouse and GE branded receivers and parts used by home constructors, originally for a limited market of amateur radio enthusiasts. By 1922, the rise of broadcasting had dramatically increased the demand for radio equipment by the general public, and this development was reflected in the title of RCA's June 1, 1922, catalog, "Radio Enters the Home". RCA began selling receivers under the "Radiola" name, marketing equipment produced by GE and Westinghouse under the production agreement that allocated a 60%–40% ratio in output between the two companies. Although the patent cross-licensing agreements had been intended to give the participants domination of equipment sales, the tremendous growth of the market led to fierce competition, and in 1925 RCA fell behind Atwater Kent as the leader in receiver sales. RCA was particularly hamstrung by the need to coordinate its sales within the limits of the GE/Westinghouse production quotas, and often had difficulty keeping up with industry trends. However, it made a key advance in early 1924 when it began to sell the first superheterodyne receivers, whose high level of performance increased the brand's reputation and popularity. RCA was the exclusive manufacturer of superheterodyne radio sets until 1930. Until late 1927, all RCA receivers ran on batteries, but at that point plug-in AC sets were introduced, which provided another boost in sales. Vacuum tubes RCA inherited American Marconi's status as a major producer of vacuum tubes, which were branded Radiotron in the United States. Especially after the rise of broadcasting, they were a major profit source for the company. RCA's strong patent position meant that the company effectively set the selling prices for vacuum tubes in the U.S., which were significantly higher than in Europe, where Lee de Forest had allowed a key patent issued to him to lapse. RCA was responsible for creating a series of innovative products, ranging from octal base metal tubes co-developed with General Electric before World War II, to miniaturized Nuvistor tubes used in the tuners of the New Vista series of television receivers. The Nuvistor tubes were a last major vacuum tube innovation, along with General Electric's Compactron, and were meant to compete with the newly introduced transistor. By 1975, RCA had completely switched from tubes to solid-state devices in their television sets, except for the cathode ray tube (CRT) picture tube itself. Phonographs and records The rapid rise of radio broadcasting during