We use Optical Character Recognition (OCR) during our scanning and processing workflow to make the content of each page searchable. You can view the automatically generated text below as well as copy and paste individual pieces of text to quote in your own work.
Text recognition is never 100% accurate. Many parts of the scanned page may not be reflected in the OCR text output, including: images, page layout, certain fonts or handwriting.
1949
PORTABLE RECORDING SYSTEM
171
volts for the main amplifier and 15 milliamperes unregulated at approximately 275 volts for the mixture preamplifiers and the optional phototube monitor unit. Regulation of the 180-volt circuit is provided by the two gas tubes V2 and VS. The 275-volt supply is filtered further in the amplifier to provide 5 milliamperes at 220 volts direct current at the mixer terminals.
A small fan provides forced-draft cooling for the unit, drawing cool air in past the selenium-rectifier plates and forcing the air out past the other components. The use of the forced draft allows a considerable saving in weight and space for the rectifier and still allows a reasonable safety factor in the event of failure of the ventilating system.
Fig. 10— RA-1284 power. unit — chassis bottom view.
Fig. 9 shows a front view of the power unit with the top cover removed. The air intake for the cooling system is in the center, with the exhaust on the two sides. Also shown on the front panel are the power switch, power input and plate-supply fuses, and a power pilot lamp. Receptacles for the two interconnecting cables to the amplifier unit are shown on the right. A power-input receptacle is similarly located on the left side. Side flaps protect the receptacles when the cover is installed, as already described for the RA-1282 amplifier. A bottom view of the chassis with the cover removed is shown in Fig. 10. This shows an adjustable resistor on the right for setting the lamp current within the desired -range, an adjustable resistor on the left for setting the regulating range of the gas tubes (depending on whether or