All power for the PG-13 equipment is provided by a three-unit motor-generator set. There are no
batteries except three small "C" batteries which are mounted on the filter unit. The motor-generator set
has, besides the motor, a 12 volt generator and a 600 volt generator. See section 37. The 12 volt
generator furnishes current for the filaments of all tubes, exciter lamps, pilot lights and for the field of
both the stage speaker and the monitor speaker. The 600 volt generator furnishes plate current for all
tubes and also furnishes polarizing voltage for the photo-electric cells.
Both generators are excited by the 600 volt machine. Standard equipment is provided with a 110 volt, 60
cycle, single-phase motor. A 110 volt direct current motor is used in some cases. Converting equipment
is used if neither 110 volt direct current nor 110 volt, 60 cycle alternating current is available.
The motor-generator set is provided with a control board which contains two rheostats, one for
controlling the voltage of the 12 volt generator and one for controlling the voltage of the 600 volt
generator. Both rheostats are operated by means of one rheostat control handle. See Figure 129. This
panel also contains a 12 volt meter, a 600 volt meter and a motor switch. Behind the control panel and
mounted as an integral part of it, is a fuse block containing fuses for the motor
and for each generator. See Figure 36. The motor-generator set stands on a felt pad which eliminates
noise and vibration, and the entire assembly is covered by a perforated metal case. Two lines of conduit
run from the generator to the amplifier. The power line runs directly to the motor-generator set.