Agilent/Keysight 8556A

The Agilent/Keysight 8556A is a low-frequency spectrum analyzer plug-in section for the 141T mainframe, operating from 20 Hz to 300 kHz. It delivers precise amplitude and frequency measurements across the audio spectrum, supporting dBV, dBm, and Volts measurement units. The 8556A integrates with IF and display sections to form a complete modular spectrum analysis system.

Technical Specifications

• Frequency Range: 20 Hz to 300 kHz


• Tuning Dial Ranges: 0–30 kHz and 0–300 kHz


• Scan Width: 10 calibrated settings from 20 Hz/div to 20 kHz/div (1, 2, 5 sequence); 0–10f preset scans from 200 Hz to 200 kHz


• Resolution Bandwidth: 10 Hz to 10 kHz


• Sensitivity: –152 dBV (25 nV) minimum detectable signal at 10 Hz bandwidth


• Input Level Control: 50 dB attenuation and preamplification range


• Maximum Input Level: –60 dBm/dBV to –10 dBm/dBV for 70 dB spurious-free dynamic range


• Amplitude Measurement Units: dBV, dBm, Volts


• Reference Level Accuracy: ±0.2 dB (control); ±0.25 dB (vernier)


• Amplitude Measurement Accuracy: ±0.95 dB


• Log Gain Control: 90 dB IF gain in 10 dB steps, ±0.2 dB (±2.3%)


• Log Vernier: 12 dB continuous range; ±0.1 dB (±1.2%) at 0, –6, –12 dB; ±0.25 dB (±2.8%) elsewhere


• Frequency Accuracy: ±3 Hz (with tracking generator output reference)


• Spurious Response: >70 dB below input signal (5 kHz–300 kHz); >60 dB (20 Hz–5 kHz)


• Third-Order Intermodulation: >70 dB below input level (signal separation >300 Hz)


• Residual Responses: <–120 dBm/dBV (0–500 Hz, 600 Ω termination, –60 dBm/dBV input level)

Key Features

• Balanced and unbalanced input signal accommodation


• 10 Hz bandwidth optimized for carrier-adjacent measurements and power line sideband analysis


• 50 dB dynamic range control with integrated attenuation and preamplification


• Modular architecture requiring compatible IF and display sections

Typical Applications

• Audio frequency spectrum analysis


• Low-frequency signal characterization


• Power line harmonic and intermodulation measurements

Compatibility & Integration Designed as a plug-in for the 141T Spectrum Analyzer mainframe. Operates in conjunction with IF sections such as the 8552B and display units.