TB 9-6625-086-35
7
9. Zero and Vernier
a. Performance Check
(1) On model 431C, connect dc voltmeter (A3) to the TI DVM output (rear panel)
using adapter (B1) and if necessary cables (B3) and (B4).
(2) On model 431B, connect resistance decade (A6)(set at 1000 ohms) to the TI
RECORDER output, using adapter (B2) and cables (B3 and B4). Connect the dc voltmeter
to the same terminals of the resistance decade, using cables (B3 and B4) if necessary.
(3) Position the TI RANGE switch to the .01 MW position and adjust the zero
controls for 0.00 volt dc on the dc voltmeter.
(4) Turn the TI RANGE switch to .03-, .1-, .3-, l-, 3-, and 10-MW positions while
observing dc voltmeter. If the dc voltmeter does not indicate between -0.01 and +0.01 volt
in each position of the RANGE switch, perform
b
below.
b. Adjustments
. On model 431C, adjust R37 (fig. 1) for 0.00 ±.01 volt on the dc
voltmeter at each RANGE switch setting. No adjustment can be made on model 431B.
NOTE
Perform paragraph 10 below if power meter calibrator (A5) is
available as a standard. If a power meter calibrator is not
available, omit paragraph 10 and proceed to paragraph 11.
10. Range and Tracking Check with Power Meter Calibrator
a. Performance Check
(1) Connect 200-ohm thermistor mount (A8) to the TI.
(2) Position the controls of power calibrator (A5) as follows:
(a) FUNCTION switch to CURRENT OFF.
(b) MOUNT RESISTANCE to correspond with the resistance of the thermistor
mount being used.
(c) CURRENT and VERNIER fully counterclockwise.
(3) Connect the POWER METER terminals of
the power meter calibrator to the DC
CALIBRATION terminals (rear panel) of the TI, using cables (B3 and B4).
(4) Set the TI MOUNT RES switch to 200
Ω
.
(5) Set the TI RANGE switch to the .01 MW position and null and zero the meter.
