Journal of the Society of Motion Picture and Television Engineers (1950-1954)

I used in the viewfinder, provides 8 kv with [ good regulation for the 8AP4A anode. The waveform monitor employs a type j 3KP1 cathode-ray tube in a circuit ; which provides excellent focus over the | tube face. Three choices of sweep speed are provided by means of a switch on the front panel. They are: half-line rate, half-field rate, and a sweep at field rate of approximately twelve lines' duration. This latter may be used to examine the vertical synchronizing signal as a check on synchronizing signal generator operation. A calibration means is provided and the calibration may be conveniently checked by depressing the "calibrate" button on the front panel. The waveform monitor may also be used as a test oscilloscope by means of a jack on the rear panel. An edge-lighted standard IRE scale is provided in conjunction with a green filter, matched to the spectral characteristic of the PI phosphor, which provides a presentation of excellent contrast. To allow single camera intercommunication operation independent of external equipment, an intercommunication amplifier is provided in conjunction with an intercommunication system, offering great flexibility. A three-position key switch on the front panel allows three modes of system operation. With the key in the upper position, all intercommunication positions have full privileges, that is, all may talk and may listen. In the center position, only the director has full privileges and all other stations may listen only. The lower position provides a private line between camera and camera control unit to enable the operators to converse without disturbing the main intercommunication line. This is particularly useful if a camera is in trouble and cooperation between video operator and cameraman is necessary for rectification. A call button is provided at the camera which causes a light to flash at the camera control unit enabling the cameraman to attract the video operator's attention when necessary. In operation the upper switch position would be used during rehearsals, and the center position would be used while on the air to prevent interference with the director's instructions. Figure 9 serves to illustrate the functional grouping of the controls on the camera control unit. The large knobs in the lower left and righthand corners are the setup and video gain controls, respectively. The edge controls, between the large knobs, control target voltage and beam current. The pushbutton at the lower left provides a negative 2-v shift in target voltage to allow the target to be easily set to 2 v above cut-off. This provides a convenient "stepping-off" point for final targetvoltage adjustment since optimum target potential will usually be found to lie between 1.8 and 2.2 v above cutoff. The three small knobs just above the gain control, reading from left to right, are the beam-focus, image-focus, and multi-focus controls. The pushbutton to the left of these controls provides a check on waveform-monitor calibration. The key switch to the right of the waveform monitor controls the waveformmonitor sweep rate. The "transmit" switch is to the far right, with the iris indicating meter in between these two switches. Just above the transmit switch is the iris control key, and in the corresponding position on the left is the intercommunication key. Knobs at the top left and right control the picture-monitor contrast and brightness. Other controls are found under the door on top of the unit and along a panel running down the left side. The camera chain power supply is shown in Fig. 10. It is only 12£ in. high and weighs 87 Ib. Components are mounted on two standard rack panels, one of which swings out, as illustrated, to provide access to the undersides. A meter on the front panel allows measurement of all d-c voltages and currents in L. L. Pourciau: Television Camera 175