Early Color Television General Electric PA CRTThe following is from Marshall Wozniak. You can read more about early color television at his site, Visions4 Magazine. Filling in the gaps of Chromatron history, we recently researched General Electric’s work in developing their version of the Chromaton. It was called simply “PA” or Post Acceleration CRT. Work started in 1954 and by late 1956, GE developed a three gun inline post deflection tube with a wire grid and vertical phosphor stripes. The wire grid was charged with 7KV and the screen was at 25KV. The design was easy to deflect and converge, but GE encountered difficulty in aligning the grid wires with the phosphor stripes. Additionally, the back scattering of secondary electrons created haze. The haze problem was later ameliorated. Unfortunately this tube never went into production. Thank you John Atwood for releasing the documents of Avon C. Campbell, a life long engineer at General Electric. Later in 1966, the world’s first 3 gun, in-line cathode ray tube went into production as the GE “Porta Color”. See the Porta Color here. As a side note: Westinghouse worked on this approach with a prototype 20 inch PA CRT. We also learned that RCA tested the GE one gun PA and said to have “reservations”. RCA avoided at great cost, paying royalties to its competitors (think about the Philo Farnsworth litigation). RCA and GE were closely intertwined by cross licenses. Being cynical, perhaps the above described RCA one gun color tube was a GE design? We have extracted the relevant discussions by the General Electric engineering department pertaining to the PA color CRT.
Evaluation by General Electric of their own development CRT.
Summary and recommendations.
Internal General Electric engineering department photos.
General Electric focused on five competitive systems and in the end, decided to contribute development to the Apple Super-Index system as the most viable cost effective technology to compete with RCA’s tri-color shadow mask CRT.
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