C-2
Measurement Considerations
Measurement considerations
Low-level voltage measurements made using the Model 2182 can be adversely affected by
various types of noise or other unwanted signals that can make it very difficult to obtain accurate
voltage readings. Some of the phenomena that can cause unwanted noise include thermoelectric
effects (thermocouple action), source resistance noise, magnetic fields, and radio frequency
interference. The following paragraphs discuss the most important of these effects and ways to
minimize them.
NOTE
For comprehensive information on low-level measurements, see the “Low Level
Measurements” handbook, which is available from Keithley.
Thermoelectric potentials
Thermoelectric potentials (thermal EMFs) are small electric potentials generated by
differences in temperature at the junction of dissimilar metals. The following paragraphs discuss
how such thermals are generated and ways to minimize their effects.
Thermoelectric coefficients
As shown in
, the magnitude of thermal EMFs generated depends on the particular
materials involved. Best results are obtained with clean copper-to-copper connections as
indicated in the table.
Table C-1
Table C-2Material thermoelectric coefficients
Material
Thermoelectric Potential
Copper-Copper
0.2µV/°C
Copper-Silver
0.3µV/°C
Copper-Gold
0.3µV/°C
Copper-Cadmium/Tin
0.3µV/°C
Copper-Lead/Tin
1–3µV/°C
Copper-Kovar
40µV/°C
Copper-Silicon
400µV/°C
Copper-Copper Oxide
1000µV/°C
Summary of Contents for 2182
Page 1: ...www tek com keithley Model 2182 2182A Nanovoltmeter User s Manual 2182A 900 01 Rev B May 2017...
Page 18: ......
Page 22: ......
Page 23: ...1 Getting Started Getting Started...
Page 41: ...2 VoltageandTemperature Measurements Voltageand Temperature Measurements...
Page 68: ...2 28 Voltage and Temperature Measurements...
Page 69: ...3 Range Digits Rate andFilter Range Digits Rate andFilter...
Page 82: ...3 14 Range Digits Rate and Filter...
Page 83: ...4 Relative mX b and Percent Relative mX b andPercent...
Page 91: ...5 RatioandDelta Ratioand Delta...
Page 117: ...6 Buffer Buffer...
Page 123: ...7 Triggering Triggering...
Page 140: ...7 18 Triggering...
Page 141: ...8 Limits Limits...
Page 149: ...9 SteppingandScanning Steppingand Scanning...
Page 168: ...9 20 Stepping and Scanning...
Page 169: ...10 AnalogOutput Analog Output...
Page 175: ...11 RemoteOperation Remote Operation...
Page 205: ...12 CommonCommands Common Commands...
Page 221: ...13 SCPISignalOriented Measurement Commands SCPISignalOri entedMeasure ment Commands...
Page 225: ...14 SCPIReferenceTables SCPIRefer enceTables...
Page 239: ...15 AdditionalSCPI Commands Additional SCPICom mands...
Page 260: ...15 22 Additional SCPI Commands...
Page 261: ...A Specifications Specifications...
Page 263: ...B Statusand ErrorMessages StatusandError Messages...
Page 268: ...B 6 Status and Error Messages...
Page 269: ...C Measurement Considerations Measurement Consider ations...
Page 278: ...C 10 Measurement Considerations...
Page 279: ...D Model182Emulation Commands Model182 EmulationCom mands...
Page 284: ...D 6 Model 182 Emulation Commands...
Page 285: ...E Example Programs ExamplePro grams...
Page 293: ...F IEEE 488 BusOverview IEEE 488Bus Overview...
Page 307: ...G IEEE 488andSCPI ConformanceInformation IEEE 488and SCPIConform anceInforma tion...
Page 310: ...G 4 IEEE 488 and SCPI Conformance Information...
Page 311: ...H Measurement Queries Measurement Queries...
Page 316: ...H 6 Measurement Queries...
Page 317: ...I Delta PulseDelta and DifferentialConductance Delta Pulse Deltaand Dif ferentialCon ductance...