MARCHI

Heintz & Kaufman emerged from San Francisco's early radio industry. Ralph Heintz was selling radio parts with Hermann Kohlmoos in the early 1920s; Jack Kaufman later joined the business, and by the middle of the decade the firm bearing Heintz's and Kaufman's names had taken shape. It made radio and transmitting equipment as well as tubes. In the 1930s it had a factory in South San Francisco, while the 1936–37 industrial register lists its offices at 311 California Street in San Francisco. The correct spelling is Kaufman, with one final 'n', as on the company's markings.

Gammatron is the most distinctive name on the company's transmitting tubes; H&K applied for the trademark in 1930. Some early examples used unusual ways of controlling electron flow, while a later line had a grid with a welded frame and a tantalum anode. Technical accounts describe tubes able to withstand severe overloads without gas forming inside the envelope and without needing getters. Later, Gammatron also appeared on boxes of more conventional tubes, so the name alone cannot identify the internal design. Documented examples include the Gammatron 24-G, made in 1944; CHK was the firm's associated JAN military code.

Heintz & Kaufman is also connected to the beginnings of Eimac. Bill Eitel and Jack McCullough worked for H&K in the early 1930s and developed the HK 354 tube, intended to compete with the RCA 852. They left Heintz & Kaufman in 1934 and founded Eitel-McCullough. This connection concerns the people and their technical experience; it does not make the two manufacturers the same. To identify an H&K tube accurately, the company name, Gammatron trademark and specific type must be considered separately. Together they reflect both the experiments with power tubes and the later development of the catalogue.