Agilent/Keysight 35665A

The Agilent/Keysight 35665A is a dual-channel FFT-based dynamic signal analyzer delivering comprehensive signal characterization across time, spectrum, network, and amplitude domains. Built for electronics, servo-mechanical control systems, machinery vibration analysis, and noise troubleshooting, the instrument combines modular architecture with optional firmware upgrades and specialized measurement packages to match application-specific requirements.

Technical Specifications

• One-channel mode: DC to 102.4 kHz


• Two-channel mode: DC to 51.2 kHz


• Frequency spans: 195.3 mHz to 102.4 kHz (one-channel); 97.6 mHz to 51.2 kHz (two-channel)


• Frequency accuracy: ±30 ppm


• Resolution: 100, 200, 400, or 800 lines; minimum frequency resolution reaches 244 µHz (one-channel) and 122 µHz (two-channel) Amplitude and Dynamic Range


• Input range: +27 dBVrms to -51 dBVrms (3.99 mVpk to 31.7 Vpk manual or auto)


• Amplitude accuracy: ±2.92% of reading ±0.025% of full scale


• FFT mode dynamic range: 72 dB


• Swept-sine measurement mode dynamic range: 120 dB


• Octave mode dynamic range: 80 dB (per ANSI S1.11)


• Noise floor: < -130 dB/√Hz (160 Hz to 1.28 kHz)


• Input impedance: 1 MΩ ±10% shunted by < 100 pF

Key Features Measurement Capabilities Linear and cross-spectrum, power spectral density, frequency response, time waveform, auto/cross-correlation, histogram, probability and cumulative distribution functions. Trace types include log magnitude, linear magnitude, dB magnitude, phase, real, imaginary, Nyquist, Bode, and unwrapped phase in single, upper/lower, front/back, setup, waterfall, and grid formats. Input Coupling and Signal Conditioning AC, DC, and ICP current source options with A-weight filtering. Integration and differentiation available via math functions. Window functions: Hann, flat top, uniform, force, exponential. Signal Generation Standard sources include fixed sine, random, chirp, burst random, and pink noise. Optional swept-sine (Option 1D2), arbitrary waveform (Option 1D4), periodic chirp, and burst chirp capabilities enable extended test configurations.

Typical Applications Electronics characterization, servo and electronic control system analysis, machinery vibration measurement, and general noise and vibration diagnostics.