Gridless Gammatron prototype, c.1929

Heintz & Kaufman Gammatron

In order not to infringe on de Forest patents held by RCA for the grid, getter, internal insulators and the Western Electric patent for the filament material, Ralph Heintz began experimenting with a redesigned Simpson vacuum tube, whose patent was owned by his contractor, Robert Stanley Dollar.  The result was the “gridless gammatron,” an electrostatically controlled tube without the now-conventional control grid.

Seven breadboard models of electronic circuits were used by Heintz & Kaufman to defend against a patent suit filed by Radio Corporation of America (RCA) in 1936, challenging Heintz’s design for the gridless gammatron. The breadboards proved the validity of H&K’s design but also suggested that RCA’s own patents were based on questionable work. RCA’s legal counsel withdrew the complaint rather than open up the question of their own patents, and Heintz and Kaufman agreed to RCA’s settlement offer of production rights for a small royalty fee.