Agilent/Keysight 8555A

The Agilent/Keysight 8555A is a modular RF section that extends the frequency analysis capabilities of compatible Agilent/Keysight mainframes by functioning as a superheterodyne receiver. It enables spectrum scanning and visualization in the frequency domain, plotting signal amplitude against frequency on a calibrated CRT display for absolute and relative measurements of signal parameters.

Technical Specifications

• Internal mixer: 10 MHz to 18 GHz


• External mixer (with waveguide mixer and adapters): 12.4 GHz to 40 GHz


• Harmonic mixing support: n = 1, 2, 3, 4, 6, and 10 for extended coverage to 42 GHz


• Dial accuracy: n × (±15 MHz) where n is the mixing mode


• Long-term frequency drift (after 2-hour warm-up): ±3.0 kHz/10 min (stabilized); 25 kHz/10 min (unstabilized) Amplitude Measurement


• Display: Calibrated in dBm or µV/mV across 50-ohm system


• Logarithmic display: 70 dB range at 10 dB/division; ±0.25 dB/dB accuracy (max ±1.5 dB full scale)


• Linear display: 0.1 mV/div to 100 mV/div; ±2.8% accuracy of full 8-division deflection


• Input attenuator: 0 to 50 dB in 10 dB steps


• Sensitivity: Typical -125 dBm (125 nV) at 1 kHz bandwidth


• Log reference level: ±0.2 dB accuracy; vernier ±0.1 dB at 0, -6, and -12 dB positions Resolution Bandwidth


• IF bandwidths: 100 Hz to 300 kHz in 1-3-10 sequence


• 3 dB point accuracy: ±20% (±15% at 10 kHz)


• Selectivity: 60 dB/3 dB bandwidth ratio


• Minimum useable RBW: 300 Hz; down to 100 Hz resolution Scan Characteristics


• Scan rates: 16 internal rates from 0.1 ms/div to 10 sec/div (1, 2, 5 sequence)


• Scan time accuracy: ±10% (0.1–20 ms/div); ±20% (50 ms/div–10 sec/div)


• Frequency scan width: 2 kHz/div to 200 MHz/div in 2, 5, 10 sequence


• Automatic tuning stabilization (phase-lock) for narrow-range scanning with minimal jitter

Key Features

• Preselector reduces spurious responses and enhances dynamic range


• Calibrated harmonic mixing extends measurement capability to multiple harmonics


• Dual display modes (logarithmic and linear) for flexible signal analysis


• Precision frequency scanning with 16 selectable rates

Typical Applications

• Broadband RF signal monitoring and analysis


• Harmonic content measurement and characterization


• Dynamic range testing across 10 MHz to 42 GHz


• High-sensitivity power and spectral density measurements

Compatibility & Integration Designed to operate with Agilent/Keysight 8552 IF section and 140-series display sections. Requires appropriate external mixer and waveguide adapters for operation above 18 GHz.