Keithley 1801, Инструкция по эксплуатации, Страница: 8 / 93

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3 Operation
3.1 Introduction ..................................................................................................................................................... 3-1
3.2 Preamplifier operation .................................................................................................................................... 3-1
3.2.1 Power-up detection ................................................................................................................................ 3-1
3.2.2 Preamplifier configuration menu ........................................................................................................... 3-2
3.2.3 Enabling Model 1801 operation ............................................................................................................ 3-2
3.2.4 Preamp ON/OFF states .......................................................................................................................... 3-2
3.2.5 Preamplifier filtering ............................................................................................................................. 3-4
3.2.6 Operational differences ......................................................................................................................... 3-5
3.2.7 IEEE-488 bus operation ........................................................................................................................ 3-7
3.3 Measurements ................................................................................................................................................. 3-7
3.3.1 DC voltage measurements ..................................................................................................................... 3-7
3.3.2 AC voltage measurements ..................................................................................................................... 3-9
3.3.3 Four-wire resistance measurements .................................................................................................... 3-11
3.3.4 Frequency measurements .................................................................................................................... 3-11
3.3.5 Differential thermocouple temperature measurements ....................................................................... 3-14
3.4 Measurement considerations ......................................................................................................................... 3-18
3.4.1 Thermoelectric potentials .................................................................................................................... 3-18
3.4.2 Source resistance noise ........................................................................................................................ 3-20
3.4.3 Magnetic fields .................................................................................................................................... 3-21
3.4.4 Electromagnetic interference (EMI) .................................................................................................... 3-22
3.4.5 Ground loops ....................................................................................................................................... 3-22
3.4.6 Shielding .............................................................................................................................................. 3-22
4 Performance Verification
4.1 Introduction ..................................................................................................................................................... 4-1
4.2 Environmental conditions ............................................................................................................................... 4-1
4.3 Warm-up period .............................................................................................................................................. 4-2
4.4 Line power ...................................................................................................................................................... 4-2
4.5 Recommended test equipment ........................................................................................................................ 4-2
4.6 Verification limits ........................................................................................................................................... 4-2
4.7 Restoring default conditions ........................................................................................................................... 4-3
4.8 Verification procedures ................................................................................................................................... 4-3
4.8.1 DC volts verification ............................................................................................................................. 4-3
4.8.2 AC volts verification ............................................................................................................................. 4-6
4.8.3 Resistance verification .......................................................................................................................... 4-6
5 Service Information
5.1 Introduction ..................................................................................................................................................... 5-1
5.2 Calibration ...................................................................................................................................................... 5-1
5.2.1 Environmental conditions ..................................................................................................................... 5-1
5.2.2 Warm-up period .................................................................................................................................... 5-1
5.2.3 Line power ............................................................................................................................................. 5-2
5.2.4 Recommended calibration equipment ................................................................................................... 5-2
5.2.5 Offset adjustments ................................................................................................................................. 5-2
5.2.6 Normal calibration ................................................................................................................................. 5-4
5.2.7 Gain constants calibration ..................................................................................................................... 5-9