172. Description of the PA-1 Loudspeaker Switching Panel. -At the bottom of one rack is a loudspeaker
switching panel. The corresponding panel at the bottom of the other rack is blank. The switch in the
upper left-hand corner is for switching the speakers from one amplifier to the other. The switch in the
upper right-hand corner is for switching the speakers "on" and "off." The row of switches at the bottom
of the panel are for switching the speakers "on" and "off" separately or in groups.
173. PG-1 Motor-Generator Sets. -The four unit motor-generator sets used with PG-1 equipments are
described in section 36.
174. Storage Batteries Used with the PG-1 Equipment. -Two Type XCR-19 storage batteries are used with
each motor-generator set. These batteries are connected in series to give 12 volts and are connected
across the 15 volt generator. The ammeter on the metering panel indicates the battery current, a reading
to the right of mid-scale indicates that the battery is charging, and a reading to the left indicates
that the battery is discharging. The purpose of the battery is to filter out the ripple of the DC voltage
from the 15 volt generator and is not used to supply current to the amplifier, but it should be kept
charged at all times. See section 51.