Journal of the Society of Motion Picture Engineers (1930-1949)

Record Details:

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placed up to 1 500 ft from the bus by the outlay of only 3000 ft of RG1 1/U coaxial cable, and ten small lengths of RG59/U to couple the boxes to the receivers. To accomplish this same feat using the standard distribution amplifiers carried in the receiver bus would mean running 15,000 ft of special cable (single coaxial and an audio pair). Eleven 500-ft lengths of this special cable were supplied with the system but along with the distribution amplifiers are now relegated to emergency and special service. Program audio signal is received on a single-channel FM receiver with double conversion. A four element yagi is used as an antenna. The receiver output feeds the Dumitter, a monitor amplifier, and a multi-winding transformer with one input and eleven outputs. This transformer provides a direct "line" feed to the receivers when desirable. Three auto-transformers boosting the line voltage 5 v feed eleven a-c outlets located in the rear of the bus. These outlets are used in conjunction with 5,500 ft of two-wire #12 cable, carried in the receiver power bus, to provide power to the receivers. The autotransformers make up for the losses incurred by long power runs. The Receiver Power Bus The layout of this vehicle is quite similar to that of the transmitter power bus. The main difference is that it has one 15-kva motor generator which allows for a larger rear compartment. This compartment contains ten reels which hold 500 ft of microwave cable, 250 ft of four-wire #6 power cable, 5,500 ft of special receiver cable, 5,500 ft of two-wire #12 receiver power cable, 2,000 ft of RG11/U coaxial cable, and 1,500 ft of RG59/U coaxial cable. This compartment also houses two workbenches. One of these is set up as a receiver test bench complete with television sweep generator, sweep calibrator, vacuum tube voltmeter and oscillo graph. Cabinets and drawers, below the workbenches and reels, house spare tubes and parts. The Kinescope Recording Bus This unit is the latest addition to the system. The vehicle is a Fagoil-type "Twin Coach." It is a standard Army vehicle and is ordinarily used as a 36passenger bus or for carrying litter patients. Upon receiving this unit we removed the seats, blanked out the windows and in general, made the operating section of the bus light-tight. A plywood partition with a sliding door separates the cab from the operating section. Ordinarily, prints are made of the "kine-recordings" so negative recording is used and the sound recorded on a Westrex 16mm portable tape recorder. When only a single print is desired positive recording is used and the sound recorded right on the film by a Maurer sound head. At the time of writing no development and printing methods have been established since the installation has not been completed. As mentioned previously, the iconoscope film chain is now located in this vehicle. The chain has been laid out in such a way that one man can handle the operation without leaving his operating chair. The bus contains cabinets for film and spare parts storage. Two reels contain enough cable to locate this vehicle up to 150 ft from the transmitter bus. The reels are accessible from the outside of the vehicle. Employment of the System After a period of testing and break-in the unit embarked on its first mission 1 8 February 1952. This mission was to provide television facilities for the Army Field Force Commanders' Preventive Maintenance Course held at Aberdeen Proving Ground, Maryland. Upon arrival demonstrations were set up and a weekly schedule arranged. Four of John S. Auld: Mobile Television System 467