Thermoelectric Effect Error Correction For 478A / 431 Combination; Thermoelectric Error For 478A / 432 Combination - Keysight 478A Operating And Service Manual

Thermoelectric Effect Error Correction for 478A / 431 Combination

Use the following technique to correct for thermoelectric effect error.
1 Measure power
2 Connect an Keysight model 8402 power meter calibration to the power meter
3 Zero and null power meter.
4 By DC substitution (refer to procedure in 431 Manual), duplicate power
5 Reverse connection polarity between the calibrator and power meter.
6 Re-zero and re-null power meter, if necessary.
7 By DC substitution, duplicate lower measurement made in step 1. Calculate
8 Calculate arithmetic mean of the two substitution powers P

Thermoelectric Error for 478A / 432 Combination

The thermoelectric errors present in the 431 are minimized in the 432 since the
thermoelectric voltage is negligible compared with the DC voltage used to bias
the thermistor bridges.
Keysight 478A Operating and Service Manual
DC CALIBRATION AND SUBSTITUTION connector.
measurement made in step 1. Calculate and record substituted power as P
and record substituted power as P
This mean power includes a correction for thermoelectric effect error.
P + P
1 2
Power = - - - - - - - - - - - - - -
2
2.
Operation 2
.
1
and P .
1 2
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