Test Considerations; Input Connections - Agilent Technologies U3402A User's And Service Manual

U3402-90001.book Page 64 Friday, July 24, 2009 4:04 PM
4 Performance Test

Test Considerations

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For optimum performance, all procedures should comply with the following
recommendations:
• Ensure that the calibration ambient temperature is stable and between
18 °C and 28 °C. Ideally the calibration should be performed at 23 °C ±1 °C.
• Ensure ambient relative humidity is less than 80%.
• Allow a one- hour warm- up period with a shorting plug connected to the Hi
and Lo input terminals.
• Use shielded twisted pair Teflon- insulated cables to reduce settling and
noise errors. Keep the input cables as short as possible.
• Connect the input cable shields to earth ground. Connect the calibrator Lo
source to earth ground at the calibrator except where noted in the
procedures. It is important that the Lo to earth ground connection be made
at only one place in the circuit to avoid ground loops.
Because the instrument is capable of making very accurate measurements, you
must take special care to ensure that the calibration standards and test
procedures used do not introduce additional errors. Ideally, the standards
used to verify and adjust the instrument should be an order of magnitude more
accurate than each instrument range full- scale error specification.

Input Connections

Test connections to the instrument are best accomplished using the dual
banana plug with copper wire short between two terminals for low- thermal
offset measurement. Shielded, twisted- pair, Teflon interconnect cables of
minimum length are recommended between the calibrator and the multimeter.
Cable shields should be earth ground referenced. This configuration is
recommended for optimal noises and settling time performance
during calibration.
U3402A User's and Service Guide