Agilent/Keysight 3403C

The Agilent/Keysight 3403C is a True RMS voltmeter engineered for precision AC and DC voltage measurements across frequencies from DC to 100 MHz. It excels at characterizing complex signals - noise, multiplexed waveforms, modulated carriers, and signals with significant harmonic content - where True RMS accuracy is essential. Though discontinued, the instrument remains valuable for laboratory and field applications demanding reliable broadband voltage analysis.

Technical Specifications

• DC, AC, and AC + DC True RMS measurements


• Six voltage ranges: 10.00 mV (AC only), 100.0 mV, 1.000 V, 10.00 V, 100.0 V, 1000 V


• AC frequency span: 2 Hz to 100 MHz (Slow response); 25 Hz to 100 MHz (Fast response)


• >90% overrange capability on all ranges, subject to maximum input voltage limits


• Crest factor: 10:1 at full range


• Overrange annunciator at ~190% of full scale; underrange at ~17% of full scale Response & Display


• Fast response: 1 second to ±0.1% of input change; 4 readings/second


• Slow response: 10 seconds to ±0.1% of input change; 2 readings/second Input Characteristics


• Input impedance below 10 MHz: 10 MΩ ±10% (1 V–1000 V ranges, 24 pF ±10% shunt); 20 MΩ ±10% (10 mV/100 mV ranges, 20 pF ±10% shunt)


• Maximum input: 1000 V RMS, 1500 V peak across all ranges


• Maximum DC in AC mode: 500 V DC


• Floated low to chassis: ±500 V DC (requires special banana-to-BNC adapter)


• Accuracy: 0.4% to 10% depending on range and frequency


• DC zero adjustment available Input & Output


• BNC front panel connector standard (low-to-high terminals)


• Analog recorder outputs for continuous monitoring


• dB recorder output: 200 mV for 20 dB, 1 kΩ ±500 Ω output impedance


• Rear panel connector option (AC converter module reversal)

Key Features

• Selectable Fast/Slow response modes for signal characterization flexibility


• Optional autoranging (Opt 001) or autoranging with remote control and digital output (Opt 003)


• dB display option (Opt 006) with front-panel reference adjustment


• Dual power supply: 115 V or 230 V ±10%, 48 Hz to 440 Hz


• Maximum power consumption: 35 VA

Typical Applications

• Broadband AC/DC voltage measurement in complex signal environments


• Harmonic and noise characterization on communication and power systems


• Modulated signal analysis across 2 Hz to 100 MHz


• Laboratory metrology requiring True RMS accuracy

Compatibility & Integration Analog and dB recorder outputs enable integration with strip-chart recorders and data acquisition systems. Remote control capability via Opt 003 supports automated test sequences. BNC and internal rear connector options accommodate various measurement configurations.