Agilent/Keysight 400E

The Agilent/Keysight 400E is a precision AC voltmeter designed for voltage and decibel measurements across audio through RF frequencies. The instrument features dual scales—linear AC voltage and logarithmic dB—making it suitable for signal analysis, testing, and calibration work where accurate RMS response is required.

– Technical Specifications

• Voltage Measurement: 1 mV to 300 V full scale across 12 ranges
• Frequency Range: 10 Hz to 10 MHz
• dB Range: -72 dBm to +52 dBm
• Input Impedance: 10 MΩ on all ranges
• Input Capacitance: Less than 25 pF typical; less than 12 pF on select ranges
• Overload Protection: 500 V RMS AC; 300 V DC maximum
• AC Amplifier Output: 150 mV RMS open circuit at full-scale meter indication
• Meter Calibration: Absolute average value response; calibrated in RMS volts
• Weight: Approximately 10 lbs

– Key Features

• Frequency response from 10 Hz to 10 MHz enables measurement across audio, low RF, and VHF applications
• Accuracy of ±1% across 40 Hz to 2 MHz band; ±2% at 20–40 Hz and 2–4 MHz; ±4% at 10–20 Hz and 4–10 MHz
• High input impedance (10 MΩ) minimizes circuit loading during measurement
• Low input capacitance reduces frequency-dependent effects on high-impedance sources
• Dual-scale readout permits direct voltage and dB level assessment without conversion
• AC to DC converter or wideband amplifier operation extends utility beyond standard voltmeter function

– Typical Applications

• Audio and subsonic signal measurement
• RF and microwave circuit testing up to 10 MHz
• Signal calibration and verification
• Frequency response analysis requiring RMS-calibrated response

– Compatibility & Integration

The 400E operates as a standalone instrument. AC amplifier output (150 mV RMS at full scale) permits integration with external recording or analysis equipment.