MM0474
Figure 1.
Model 431C power meter.
full scale.
By selector switch, the instrument normalizes the power meter
reading to compensate for the Calibration Factor of a thermistor mount used for
a given measurement. Complete specifications are presented in Table 1.
(2) The Model 431C makes provision for using the DC substitution method
of measuring RF power and to assure accuracy of the power meter calibration.
Outputs are provided for a digital voltmeter readout, permanent recording of
measurements operation of alarm or control system, or to allow the Power Meter
to be used in a closed-loop leveling system.
(3) Accessories. Two accessories are supplied with the Model 431C Power
Meter: a 7.5 foot (2290 mm) detachable power cable and a 5 foot (1520 mm) cable
that connects a thermistor mount to the instrument.
Thermistor mounts are
available (refer to Table 2) but are not supplied with the power meter.
b. Model 431C, Principles of Operation.
(1) The Model 431C is an automatic self-balancing power-measuring
instrument employing dual-bridge circuits.
The power meter is designed to
operate with temperature-compensated thermistor mounts such as the 8478B and
478A Coaxial and 486A Waveguide series. Power may be
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