The National Union Radio Corporation was incorporated in September 1929 to acquire the assets of three radio tube manufacturers; Sonatron Tube Company; Televocal Corporation; and the Magnatron Corporation. This merger occurred during a period in which the demand for radio tubes was extraordinary. Through much of the 1920s the demand for tubes had been primarily for use in radio sets, which by 1929 numbered over nine million due to the growth of the radio broadcast industry. Each of these sets used between three to twelve tubes. The result was that between 1927 and 1928 the number of tubes sold for use in radio sets alone grew 82.8 percent. There was also the expectation that tube sales would be furthered by their use in other electrical devices such as phonographs, talking movies, televisions, and long-distance telephones.
The creation of National Union Radio is an example of the consolidation that was occurring in the radio tube industry during this period and the need to standardize the wide variety of tubes available. Other radio tube manufacturers were merging as well during this time. For example, Sonatron, one of the companies to be acquired by National Union, had itself been formed by the merger of four smaller radio tube companies in 1928.
The actions of Radio Corporation of America (RCA) appear to have driven the National Union Radio deal. In this deal, RCA lent the newly formed National Union Radio two million collars for a period of five years at 5 percent interest. The National Union Radio Corporation also entered into a reciprocal license agreement with RCA, General Electric (GE), and Westinghouse to manufacture radio tubes under the patents owned by these companies. This provided RCA, GE, and Westinghouse with greater control over the cost and production of tubes used by their products and a ready market for the radio tubes that would be manufactured by National Union Radio.
The National Union Radio Corporation remained a major manufacturer of radio and television tubes for several years after 1929. It continued to operate under that name until June 1954, when it became the National Union Electric Corporation. In November 1954 the company sold its TV tube manufacturing facilities to Sylvania. Finally, in 1960, National Union Electric merged with Eureka-Williams. By this time, National Union had moved so far away from its original lines of business that at the time of its merger it was described as a "heating and air-conditioning manufacturer."