Eimac

Eimac is a trade mark of Eimac Products, part of the Microwave Power Products Division of Communications & Power Industries. It produces power vacuum tubes for radio frequency applications such as broadcast and radar transmitters.

The San Francisco Bay Area was an early center of ham radio with about 10% of the operators in the United States. William Eitel, Jack McCullough, and Charles Litton, Sr., who together pioneered vacuum tube manufacturing in the Bay Area, were hobbyists with training in technology gained locally who participated in development of shortwave radio by the ham radio hobby. High frequency, and especially, Very high frequency, VHF, transmission in the 10 meter band, required higher quality power tubes than were manufactured by the consortium of RCA, Western Electric, General Electric, Westinghouse which controlled vacuum tube manufacture. Litton pioneered the glass lathe which made mass production of reliable high quality power tubes possible.

While employed by the small San Francisco, California manufacturing firm of Heintz & Kaufman which manufactured custom radio equipment Bill Eitel (amateur radio call sign W6UF) and Jack McCullough (W6CHE) convinced company president Ralph Heintz (W6XBB) 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.

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