HP / Agilent 34420A Micro-Ohm Meter, 7 Digit

The Agilent 34420A NanoVolt/Micro-Ohm Meter is a precision instrument for low-level DC voltage, resistance, and temperature measurements. It delivers 7½ digit resolution with exceptional sensitivity—100 pV for voltage and 100 nΩ for resistance—making it ideal for characterizing small electrical parameters in research, calibration, and quality assurance workflows.

The meter excels at micro-ohm measurements across 1 Ω to 1 MΩ ranges with 60 ppm accuracy (1-year). Four dedicated measurement modes—standard, low-power, and voltage-limited—accommodate diverse test scenarios. Two- and four-wire resistance configurations with offset compensation minimize thermal EMF errors. DC voltage sensitivity reaches 1.3 nVrms noise floor across 1 mV to 100 V ranges, with 24-hour DCV accuracy of 2 ppm basic.

Temperature capability spans SPRT, RTD, thermistor, and thermocouple sensors. SPRT accuracy is 0.003°C plus probe accuracy, with built-in ITS-90 conversion for standard platinum resistance thermometers. Thermocouple range extends to -210°C to 1820°C; thermistor operation covers -80°C to 150°C.

– Technical Specifications

• Display & Memory: 7½ digit resolution; 1024 reading memory
• DC Voltage: 100 pV sensitivity; 1.3 nVrms noise; 1 mV to 100 V ranges; 30 ppm accuracy (1-year)
• Resistance: 100 nΩ sensitivity; 1 Ω to 1 MΩ ranges; 60 ppm accuracy (1-year); 2- and 4-wire modes; voltage limits to 20 mV, 100 mV, or 500 mV
• Temperature Sensors: SPRT (0.003°C accuracy), RTD (4.9 Ω to 2.1 kΩ, 4-wire), thermistor (-80°C to 150°C), thermocouple (-210°C to 1820°C)
• Integration Time: Adjustable NPLC; reading rates to 250/s (GPIB)
• Interfaces: GPIB (IEEE-488), RS-232; SCPI and Keithley 181 command modes
• Math Functions: Min, max, average, peak-peak, scaling, null, difference, ratio
• Filtering: Selectable analog and digital
• Power: 100/120/220/230/240 VAC ±10%; 25 VA peak; 45–66 Hz and 360–440 Hz lines
• Operating Temp: 0°C to 55°C

– Key Features

• Two-channel integral scanner with built-in ratio and difference functions for voltage comparisons
• Offset compensation to suppress thermal transients in low-resistance tests
• Shielded, low-thermal front panel connectors with 99% copper contacts
• Configurable integration rates and autorange operation (>30/s voltage autorange)

– Typical Applications

Calibration of precision voltage and resistance standards, contact resistance measurement in connectors and switches, thermal characterization of sensors and probes, and low-noise DC measurements in physics and materials research.

– Compatibility & Integration

GPIB and RS-232 interfaces enable remote operation and data logging in automated test systems. SCPI and Keithley 181 compatibility support legacy and modern control architectures.