It was 1929, and William W. Eitel had come to San Francisco to ask Ralph Heintz for a job. “What kind of work are you doing now?” asked Heintz. “I’m driving a grocery wagon.” “What other things do you have to recommend you?” “I’m a radio ham.” “Well, that’s good enough,” said Heintz. After only a few months, Eitel was put in charge of the Heintz and Kaufman tube department as H&K ramped up to equip the Dollar steamship line with shortwave radio.
Eitel’s enthusiasm for his work was infectious: his amateur radio friend Jack A. McCullough (1907-2001) joined the company in 1930. The two worked for Heintz until 1934, when they launched their own three-person company in San Bruno, directly competing with H&K. A small advertisement in the November 1934 issue of the radio amateur magazine QST announced their new tube, the 150T, that claimed to be more reliable and longer lasting than any similar tube.
Orders came in from commercial users, amateurs, and the U.S. Naval Research Lab. By 1939, EIMAC supplied tubes for the first Navy sea radar tests and the new Armstrong FM radio broadcast service. During World War II, 1,800 EIMAC employees worked around the clock to produce 4,000 radar tubes a day — 120,000 a month — supplying the government with a variety of power transmitting tubes.
After weathering the post-war drop in orders, EIMAC was part of the electronics industry boom in the 1950s, producing a new tetrode tube, and larger tubes for radio and television. When they moved into their new multi-million-dollar plant in San Carlos in 1958, a radio signal was bounced off the moon, using a giant EIMAC klystron. EIMAC soon became the world’s largest independent manufacturer of electron power tubes used in satellite communication, and a host of other applications including nuclear research and computer data networks. In 1965, EIMAC merged with Varian Associates.
The Perham Collection of Early Electronics includes a comprehensive collection of EIMAC tubes, including experimental tubes never put into production, as well as product literature and corporate publications.
Between 2018-2019, volunteers photographed and cataloged all of the EIMAC tubes in the Perham Collection. View them in our online catalog.
A selection of EIMAC tubes at History San Jose