<P> CBS began experimental color field tests using film as early as August 28, 1940, and live cameras by November 12 . NBC (owned by RCA) made its first field test of color television on February 20, 1941 . CBS began daily color field tests on June 1, 1941 . These color systems were not compatible with existing black - and - white television sets, and as no color television sets were available to the public at this time, viewing of the color field tests was restricted to RCA and CBS engineers and the invited press . The War Production Board halted the manufacture of television and radio equipment for civilian use from April 22, 1942 to August 20, 1945, limiting any opportunity to introduce color television to the general public . </P> <P> As early as 1940, Baird had started work on a fully electronic system he called the "Telechrome". Early Telechrome devices used two electron guns aimed at either side of a phosphor plate . The phosphor was patterned so the electrons from the guns only fell on one side of the patterning or the other . Using cyan and magenta phosphors, a reasonable limited - color image could be obtained . He also demonstrated the same system using monochrome signals to produce a 3D image (called "stereoscopic" at the time). Baird's demonstration on August 16, 1944 was the first example of a practical color television system . Work on the Telechrome continued and plans were made to introduce a three - gun version for full color . However, Baird's untimely death in 1946 ended development of the Telechrome system . </P> <P> Similar concepts were common through the 1940s and 50s, differing primarily in the way they re-combined the colors generated by the three guns . The Geer tube was similar to Baird's concept, but used small pyramids with the phosphors deposited on their outside faces, instead of Baird's 3D patterning on a flat surface . The Penetron used three layers of phosphor on top of each other and increased the power of the beam to reach the upper layers when drawing those colors . The Chromatron used a set of focusing wires to select the colored phosphors arranged in vertical stripes on the tube . </P> <P> In the immediate post-war era the Federal Communications Commission (FCC) was inundated with requests to set up new television stations . Worrying about congestion of the limited number of channels available, the FCC put a moratorium on all new licenses in 1948 while considering the problem . A solution was immediately forthcoming; rapid development of radio receiver electronics during the war had opened a wide band of higher frequencies to practical use, and the FCC set aside a large section of these new UHF bands for television broadcast . At the time, black and white television broadcasting was still in its infancy in the U.S., and the FCC started to look at ways of using this newly available bandwidth for color broadcasts . Since no existing television would be able to tune in these stations, they were free to pick an incompatible system and allow the older VHF channels to die off over time . </P>

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