The CHARGE switch should never be left in the HIGH
position for more than 24 hours.
The high charging
rate does not affect the operation of the instrument
but it will severely reduce battery life if left on
for periods exceeding 24 hours, and excessive heating
temperature to exceed the operating temperature.
a. Front panel indicators and controls.
(1) Meter. The meter is scaled in arbitrary divisions and does not
read battery voltage. It serves three indicating functions, namely:
Heater ON/OFF - meter cycles from zero to approximately three-quarter
Battery state of charge - meter should indicate in the GREEN band
when BATT TEST switch is depressed.
approximately half scale.
(2) BATT TEST spring-return switch is used to connect the meter to
the battery to indicate the battery state of charge.
(3) AC ON lamp indicates when the unit is functioning from the ac
(4) BATT CHARGE switch is to enable the batteries to be recharged
quickly on the HIGH position and in normal use.
It is left on the LO or
trickle charge position.
(6) GALV terminals are for connection of an external galvanometer or
detector for indicating the balanced condition of the bridge.
(7) TEMP DEVIATION control is used to null the external detector and
is calibrated in terms of temperature deviation from the nominal operating
(8) CELL terminals are four pairs of highly-insulated copper
terminals with low thermal EMF characteristics to which are connected the
four saturated standard cells.
(9) GND terminal is connected to an electrostatic shield surrounding