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RCA's Television Field Trials1929 Mechanical ExperimentsRCA's first experimental television transmissions began in 1928 by station W2XBS New York in Van Cortlandt Park and then moved to the New Amsterdam Theater Building, transmitting 60 line pictures in the new 2-3 mHz band allocated to television. A 13" Felix the Cat figure made of paper mache was placed on a record player turntable and was broadcast using a mechanical scanning disk to a scanning disk receiver. The image received was only 2 inches tall, and the broadcasts lasted about 2 hours per day. By 1931 the station became part of NBC and began to transmit from 42nd St. These early broadcasts consisted of objects like Felix the Cat or early test patterns and photographs. The RCA receiver in our collection was used in these experiments. 1932 Field TrialsIn 1931 the transmitter was moved to the Empire State Building, the world’s newest and highest skyscraper and NBC erected the transmitting antenna for experimental station W2XBS. Starting in the winter of 1931, and running until mid 1932, an experimental television system had been used in New York using a studio scanning apparatus. This consisted of a mechanical disk, flying-spot type, for an image of 120 lines, 24 frames per second. The scanning disk camera in our collection was part of this apparatus. For these tests, an all-electronic receiver was used. Video transmission was at 41.0 mHz double sideband, audio at 60.0 mHz. There is no documentation of how many sets were made. Here is an article that describes reception of these broadcasts. After many years of research and development an all-electronic television system emerged from the laboratory in 1933 for actual field tests. These tests were carried out at Camden (New Jersey), using a video transmitter and connected to it by a coaxial line. Iconoscopes (television cameras) were used to pick up scenes both in the studio and out-of-doors. The use of the iconoscope permitted transmission of greater detail, outdoor pick-up, and wider areas of coverage in the studio. Experience indicated that it provided a new degree of flexibility in pick-up performance, thereby removing one of the most difficult technical obstacles to television. An electronic receiver was used for these tests, and there is no record of how many were manufactured. A scanning pattern of 240 lines made it possible to obtain a picture with good definition, but as the frame frequency was 24 cycles, without interlacing , flicker was quite noticeable. In 1934 the number of lines was increased to 343, and an interlaced pattern having a field frequency of 60 cycles and a repetition rate of 30 frames per second was adopted. 1936 Field TrialsThe results of these tests were so satisfactory that it was decided to continue them in New York City, the site of earlier RCA tests using a mechanical scanner. The advantage of the new location was that transmission studies under more nearly the conditions encountered in actual broadcasts were possible, in particular, with respect to noise and reflection from buildings. This move was made in 1935, and the second field trials began the next year. The New York studios were located in Radio City. The transmitter was installed in one of the upper floors of the Empire State Building, with the antenna on the mooring mast, 1285 feet above street level. Two links interconnected the studio and transmitter. One of these was an underground coaxial cable approximately a mile in length, the other was a radio link. Video carrier frequency was 46.5 mHz and aural carrier was 49.75 mHz. During late 1935 and early 1936 RCA manufactured a few nine-inch field test television receivers, including the RR-359 in our collection. The RR-359 started as a 9-inch mirror-in-the-lid set. The 9-inch round picture tube faced upwards and was reflected in a mirror under the lid. The lid was opened at a 45-degree angle to reflect the screen’s image toward the viewer. A rectangular mask placed over the picture tube hid most of the “roundness” and this produced an image with the now familiar 3 by 4 aspect ratio of current television in all countries. Initially the set scanned 343 lines (interlaced) and had a continuous tuner capable of tuning 40 to 90 MHz which frequencies include the current low-band VHF channels 2 to 6 and below to the now defunct channel 1. Curiously, the black dial included the labeling “amateur” between the numbers 56 and 60. This was the old 5-meter band that moved to 6 meters after World War II. The lower, extremely heavy chassis contains the power supplies and high voltage. The upper chassis, which contains the tuner, front-end and scanning circuits, is a vertical chassis mounted above with its underside (the guts) facing up against the front. The first public demonstration of these field trials took place on July 7, 1936 to RCA’s 225 licensees. Major General J. G. Harbord, chairman of the board of RCA announced that there were three sets in operation at the time, the most distant in Harrison, N. J. In mid 1936 RCA started making the RR-359B, which was a 12 inch set. A 12-inch round picture tube replaced the earlier 9-inch. The overhaul to a larger screen size may have been due to poor reviews given by the press in late 1936. The small, 9-inch tube looks more like a 7-inch screen when viewed in the mirror. That, coupled with its light-green phosphors creates more of a crystal ball effect than the desired “movies and live action in your living room” effect that the press had anticipated. The RR-359B had a larger cabinet but used the same two chassis as the RR-359. The first 12 inch sets were built with continuous tuners and 7 controls under the lid. Later versions had only 3 controls under the lid, and had a single 807 horizontal output tube in place of two 42s. These sets had detent tuners with 12 positions, and a very bizarre frequency allocation that does not simply progress higher in frequency as the tuner number goes up, but seems to jump around randomly. This may have had something to do with how they assigned the broadcast and relay channels used by RCA’s remote coverage trucks. These frequencies are now assigned to our current FM radio band (88-108 MHz) but at the time were additional (secondary) television channel assignments. In 1937, RCA and other experimental broadcasters moved up to 441-lines, AM sound. This was the RMA (Radio Manufacturer’s Association) standard in 1939 when RCA, GE, Dumont and a few others commercially introduced home television sets. The original 12 inch sets used tubes with a yellowish green phosphor. Apparently the high temperature required in the annealing discolored the phosphor. By 1937 RCA had perfected the white phosphor. About 100 of these sets were made, and they were located at various points within a radius of 50 miles of the W2XBS transmitter. These, together with field strength measurements, gave detailed information as to the effect of the terrain on the received pictures. They also facilitated obtaining data on the reaction of a great variety of people to different types of programs.
Location of Field Trial Sets None of these receivers were sold to the public, but were installed in the homes of executives and engineers. The public could see the RCA sets in the lobby of Rockefeller Center in New York. The RCA field test receivers, model RR-359, represented the first production of a home viewer in the United States, albeit a prototype model that was not for sale. Each set had cost about $1,500 to manufacture in 1930s dollars. NBC demonstrated TV to 200 invited guests on November 6, 1936. The sets used in the demonstration were all RR-359B 12 inch models. NBC (owned by RCA) also experimented with clothing that worked well with television programming. RCA encouraged amateurs to experiment with television, and sold parts for home made receivers Other RCA TestsRCA experimented with other uses of television. In 1939, RCA demonstrated television reception in and transmission from an airplane. RCA also experimented with two way television. (Thanks to Nat Pendleton, Darryl Hock and Jeff Lendaro for information used in this article)
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