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34980A Service Guide
3
Calibration Procedures
–10 Vdc Adjustment Procedure (Optional)
The –10 Vdc calibration electronically enhances the Internal DMM’s a-to-d converter
linearity characteristic. This adjustment should ONLY be performed after servicing the
A-to-D converter or replacement of the calibration RAM.
You will need an input test connector as described in
1
If a zero calibration has not been performed recently, perform one before beginning
this procedure (see
).
2
Configure the instrument as follows:
DC VOLTS
10 V range
[SENSe:]VOLTage[:DC]:RANGe 10
6½ digits
INTEG 100 PLC
[SENSe:]VOLTage[:DC]:NPLC 100
INPUT R > 10 G
[SENSe:]VOLTage[:DC]:IMP:AUTO ON
3
Measure and note the voltage offset present at the end of the measurement cable by
shorting the ends of the cable. Be sure to use a copper wire and allow enough time for
the residual thermal offset to stabilize (usually about 1 minute).
4
Connect the input cable to the calibrator output and set the calibrator to 10V.
Allow enough settling time for any thermal offset voltages to stabilize (usually about
1 minute).
5
Perform a +10V dc gain calibration.
6
Send an adjustment to the instrument. The adjustment value is the sum of the
calibrator output and the measured offset (from step 3). For example, if the calibrator
output is 10.001 volts and the measured offset is 10 µV, send the value +10.001010
volts. When the adjustment finishes, verify that new readings fall within ±20 µV of
the calibrator output plus the offset.
7
Reverse the cable connections to the calibrator to create a –10 Vdc voltage standard.
You must physically reverse the cables.
DO NOT switch the output polarity of the
calibrator.
8
Perform a –10V DC gain calibration. Be sure to allow time for thermal offsets to
stabilize (usually about 1 minute).
9
Send an adjustment to the instrument. The adjustment value is the sum of the
calibrator output and the measured offset (from step 3). Using the previous example
values, enter 10 µV minus 10.001 volts or –10.000990 volts.
10
When the adjustment finishes, verify that new readings fall
within ± 30 µV of the calibrator output minus the offset.
深圳德标仪器
135-1095-0799
Содержание Agilent 34980A
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