MM0474
circuit addition and is not operational on these units.
The RVG terminals are
floating when the switch is in the REM position.
(18) STABILIZER MODULATOR OUTPUT TERMINAL.
This terminal is a high
current output of the leveling amplifier. It will supply up to 300 mA to meet
the requirements of a ferrite modulator. The shell of the connector is tied to
terminal 4 and is insulated from the instrument chassis.
(19) STABILIZE PIN MODULATOR OUTPUT TERMINAL. This terminal is a direct
output of the leveling amplifier. The maximum output current of the amplifier
is approximately 5 mA, which provides protection for the PIN diodes. The shell
of the connector is tied to terminal 4 and is insulated from the instrument
chassis.
(20) REFERENCE GENERATOR FUNCTION SWITCH. Selects one of three different
reference generator modes of operation. To the left of center (RVG) provides
the reference voltage output, center provides the voltmeter (NULL) function,
and right of center provides the stabilizer (STAB) function.
(21) and (22)
RVG OUTPUT TERMINALS.
The various outputs associated with the
primary function of the reference voltage generator, i.e., precision power
measurement, appear at these terminals. A complete description of the voltages
available at these terminals is included in the description of the functions of
switch 17.
4.
PRELIMINARY OPERATING INSTRUCTIONS.
a. Before connecting the bolometer determine its operating resistance by
the label or stamping on the housing and whether it is a barretter or
thermistor. The following steps describe the initial operations.
(1) With instrument turned off, set BARR-THER switch according to the
type of bolometer mount being used. If this switch is not set properly it is
possible to destroy a bolometer element, particularly a barretter.
It is
advisable to turn the instrument off before changing the switch setting.
(2) Attach
the
lower
links
as
appropriate
for
the
mount
operating
(3) Make certain upper links are attached as shown and described in
Figure 4.
(4) The rear grounding link should be in place unless it is necessary to
float the instrument above ground.
108
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