Keysight / Agilent / HP 34401A 6.5 Digit Multimeter

The Keysight/Agilent/HP 34401A is a 6.5-digit digital multimeter engineered for precision measurements in benchtop and automated test environments. It delivers DC and AC voltage and current measurements, resistance (2-wire and 4-wire), frequency, period, continuity, and diode testing across a broad measurement range. The instrument achieves exceptional accuracy—0.0015% of reading + 0.0001% of range for DC voltage over 24 hours—with true RMS AC measurement capability and advanced noise rejection via dual-mode CMRR (140 dB DC, 70 dB AC). Trigger-based measurement acquisition supports up to 1000 readings/s to GPIB with 512-reading onboard memory and configurable trigger delay (0 to 3600 s). Built-in math functions include NULL compensation, min/max/average statistics, dB/dBm conversion, and limit testing with TTL output.

– Technical Specifications

Measurement Functions and Ranges:
• DC Voltage: up to 1000 V
• AC Voltage (True RMS): up to 750 V; bandwidth 3 Hz to 300 kHz (1 MHz under certain conditions)
• DC Current: up to 3 A
• AC Current (True RMS): up to 3 A
• Resistance: 100 Ω to 100 MΩ with selectable 2-wire and 4-wire modes
• Frequency: up to 1 MHz (3 Hz to 300 kHz on AC voltage/current)
• Continuity Test: selectable threshold 1 Ω to 1000 Ω

Accuracy and Resolution:
• 6.5-digit resolution
• DC Voltage Accuracy (24-hour): 0.0015% of reading + 0.0001% of range
• DC Voltage Accuracy (1-year): 0.0035%
• AC Voltage Accuracy (1-year): 0.06%
• CMRR (DC): 140 dB; CMRR (AC): 70 dB
• Normal mode rejection (100 PLC): 60 dB; (10 PLC): 60 dB

Measurement Performance:
• Direct GPIB output: up to 1000 rdgs/s
• Configuration rate: 26/s to 50/s
• Autorange rate (DC Volts): >30/s
• External trigger jitter: 10 GΩ on 100 mV range)
• Selectable reading hold sensitivity: 10%, 1%, 0.1%, or 0.01% of range
• Samples per trigger: 1 to 50,000
• Math functions: NULL, min/max/average, dB/dBm, limit testing with TTL output

– Interfaces

GPIB and RS-232 connectivity enable integration with automated test systems and direct instrument control.