Motion Picture Herald (Oct-Dec 1951)

OPERATION AND MAINTENANCE OF Theatre Teleyision Equipment —explained for managers and projectionists in a series of articles— by AARON NADELL 3. RCA Theatre System EMBODYING MOST of the general principles of television reception outlined in previous installments of this series, the RCA PT-100 Theatre Television System, shown in accompanying photos, is among the simplest — and at this time of writing, probably the most widely used — of all theatre TV equipments. It delivers its entertainment to the theatre screen directly, by optical projection and enlargement of the face of a 7-inch picture tube. Light level approaches that of motion pictures in many theatres yet today, and exceeds the brightness of movies that were commercially acceptable years ago. Clarity of detail, particularly for patrons in front rows, does not equal that of motion pictures ; however, it can do so, it is said, whenever the FCC authorizes channels able to transmit such detail. The equipment here pictured is commercial, not laboratory, apparatus. Accompanying photographs show, for example, the overflow audience at the Stanley theatre, Philadelphia, awaiting the presentation of a boxing match, with the PT-100 television projector encased at the center of the balcony. Shown also are marquee banners used by the Pilgrim theatre in Boston to advertise exclusive showing of Golden Gloves event telecast from Chicago. Control equipment pictured here is in the projection room of the RKO Fordham theatre in New York. Essentially the equipment consists of three parts, located as a rule in three different places. One component, the projector, must be placed in the auditorium, as in the accompanying view of the Stanley theatre. Where there is no balcony the projector may be mounted on a retractable boom from the ceiling (the projector weighs 400 pounds). Location requirements with respect to the projector are naturally rigid as to centering its optical axis on the center of the screen. Distance from the screen is also critical, and should be as nearly as possible 62 feet, for a screen image approximately 20 feet wide. [See^ however, report of new ranges on page 62. — Ed.] The two other components of the complete system are the high-voltage power supply, which may be installed almost anywhere, although the generator room is usually the preferred location ; and the control rack, which mounts ten different apparatus items and belongs in the projection room. It is preferably installed near, and at right angles to, the front wall, so the projectionist at the controls can look through a port and see the image on the screen by merely turning his head. SYSTEM COMPONENTS To examine the details of the PT-100 somewhat more closely, a convenient starting place will be the panel in the projection room equipment. At the right hand of the projectionist is the signal selector ; this is where the signal comes in if it comes by wire. If it comes via the air, the signal enters the panel which the projectionist is With RCA television equipment, the Pilgrim theatre in Boston thus billed a "Golden Glove" boxing broadcast from Chicago. Auditorium of the Stanley theatre, Philadelphia, showing RCA television installation and crowd awaiting a fight broadcast. manipulating with his left hand. That is the off-the-air receiver. Apparatus items mounted on the left half of the rack, from top to bottom, are the monitor, off-the-air-receiver, vertical deflector amplifier, and two 400-volt power supply units. The right half of the rack has, at top, the control panel for remote control of the projector; this panel also contains a meter and a cathode ray oscilloscope that report to the projectionist what the projector is doing and so guide him in handling the controls. Under this panel, as already noted, is the signal selector or switching panel. Third and fourth are the horizontal deflection amplifier, and the 300-volt voltage control. At bottom, right, flat panel is the high-voltage control. Note that there is a large port (shutter down) behind the projectionist’s left shoulder, through which he can observe the screen. He can also monitor his image in the 7-inch picture tube and his sound through headphones. In an accompanying photo he is shown in the act of selecting sound from the off-the-air receiver (instead of telephone line, microwave or coaxial cable) and of switching it to the theatre projector instead of to the 7-inch monitor in front of him, while simultaneously, with his left hand, he is selecting his channel on the receiver. (A normal monitor speaker replaces the headphones once the show goes on.) The projector, which is located in the BEHER THEATRES SECTION 25