Eimac

While employed by the small San Francisco, Califonia, manufacturing firm of Heintz & Kaufmann, Bill Eitel and Jack McCullough  convinced company president Ralph Heintz  to allow them to develop a transmitting tube that could operate at lower voltages than those then available to the amateur radio market, such as the RCA 204A or the 852. Their effort was a success and resulted in production of the HK-354. Shortly after in 1934, Eitel and McCullough left H&K to form Eitel McCullough Corp. in San Bruno California.

The first product  were transmitting tubes with the high performance and stable design features that were required by the Ham radio community. The first tube produced under the trade mark "Eimac" was the 150T power triode. Under the leadership of the founders, Bill Eitel and Jack McCullough, the company grew and expanded to meet the needs of the U.S. military during World War II.. The new company thrived during world war II by selling tubes to the U.S. military for use in radar equipment.

Beginning in 1947, Eimac operated FM radio station from their plant.

In need of more space, the company moved to San Carlos. Eimac's San Carlos plant was dedicated on April 16, 1959. In 1965, Eimac merged with Varian Associates and became known as the Eimac Division.

Eimac continued to advance the technology and developed modern, high-power ceramic tubes which incorporate innovative Pyrolytic graphite grids for short-wave and UHF television broadcast. Regarded as a technical innovator, Eimac has become the worldwide leader in broadcast tubes. Eimac designs and produces power tubes for broadcast, communications, radar, industrial heating, semiconductor processing, science and medical applications, with customers located in virtually every country in the world. All Eimac tubes are made in the U.S.

In 1995, Leonard Green & Partners  purchased the entire Electron Devices Business from Varian and formed Communications & Power Industries (CPI)

Eimac, now part of CPI's Microwave Power Products Division