# HP 3561A Single Channel Dynamic Signal Analyzer 0.000125 Hz to 100 kHz (Pre-Owned) # HP 3561A Single Channel Dynamic Signal Analyzer 0.000125 Hz to 100 kHz (Pre-Owned) ## Key Features At A Glance - Single channel dynamic signal analyzer covering 0.000125 Hz to 100 kHz with ±0.003% frequency accuracy - ±0.15 dB amplitude accuracy across +27 to -40 dBV input ranges; 80 dB dynamic range with full alias protection - 7.5 kHz real-time rate (fast average display); 3.0 kHz single-display real-time bandwidth - Band selectable zoom analysis resolves frequencies spaced as narrow as 640 µHz across the 100 kHz range - Operates as spectrum analyzer, network analyzer (with built-in tracking noise source), 1/3 and 1/1 octave analyzer, and time-domain waveform recorder - 40,000-sample time buffer with pre/post-trigger capture from 40k pre-trigger to 1023k post-trigger samples - HP-IB interface standard (IEEE 488-1978); controls HP-GL plotters and HP raster dump printers directly - Internal non-volatile memory stores 2 traces and 6 states; optional bubble memory stores 127 traces and states The HP 3561A is a single-channel dynamic signal analyzer covering 0.000125 Hz to 100 kHz, designed by Hewlett-Packard for electronics, vibration analysis, and acoustics applications. The datasheet describes it as 'several instruments in one' — operating in both the frequency domain as a spectrum analyzer and in the time domain as a low-frequency digital storage oscilloscope. With a built-in tracking noise source, it also serves as a network analyzer, and digital signal processing allows it to synthesize 1/3 or 1/1 octave filters for high-accuracy, drift-free octave analysis. The datasheet lists applications in electronics, vibration analysis, and acoustics. In noise and vibration measurements, transducers convert physical phenomena to voltage; the 3561A includes an internal power supply for ICP-type (integrated circuit piezoelectric) transducers, eliminating an extra piece of signal-conditioning equipment. A hardware A-weighting filter conforming to ANSI S1.4-1971 (R1976) is provided for acoustic measurements where human-ear response must be considered. The combination of octave and narrowband analysis on a single instrument supports noise and vibration work that traditionally required separate tools. ValueTronics International has specialized in test and measurement equipment since 1992, with a deep inventory of legacy Hewlett-Packard instruments that remain in active use across calibration labs, machinery balancing programs, and acoustic and vibration research environments. Every unit moves through our 20,000 sq ft facility at 1675 Cambridge Drive in Elgin, Illinois — where instruments are received, inspected, and performance-tested by our technicians before they ship. For dynamic signal analyzers like the 3561A, where amplitude accuracy and phase response are the measurement, that hands-on verification step is what separates a documented working instrument from a marketplace listing. ## Brand Heritage Hewlett-Packard's test and measurement business was spun out as Agilent Technologies in 1999, and the electronic measurement portion of Agilent became Keysight Technologies in 2014. The HP 3561A predates both transitions — it carries the original HP branding from the era when the company defined precision instrumentation. Keysight continues to support many HP-lineage products through its calibration and service infrastructure. ## Product Core & Specifications Specification Value Frequency Range 0.000125 Hz to 100 kHz Spans 0.01024 Hz to 100 kHz in a 1, 2, 2.5, 5, 10 sequence Accuracy ± 0.003% of display center frequency Resolution 0.25% of frequency span Window Flat Top, Hann, Uniform, and Exponential Bandwidth (3 dB Bandwidth, % of frequency span) Flat Top 0.90% Hann 0.37% Uniform 0.25% Real Time Bandwidth (Typical) Single display: 3.0 kHz; Fast average display: 7.5 kHz Amplitude Measurement Range +27 to -120 dBV noise floor (22.4 VRMS to 1 µV noise floor). Input range selected in 1-dB steps from +27 to -51 dBV. Optimum range determined automatically in autorange mode. Dynamic Range 80 dB Accuracy at the Passband Center +27 to -40 dBV input ranges ± 0.15 dB \-41 to -51 dBV input ranges ± 0.25 dB Flat Top window +0, -0.01 dB Hann window +0, -1.5 dB Uniform window +0, -4.0 dB Note Overall accuracy is the sum of the accuracy at the passband center plus the selected window accuracy. Resolution Log 0.01 dB Linear 4 digits Phase Accuracy ±2 degrees, dc-10 kHz; ± 10 degrees, 10-100 kHz (signals no more than 40 dB below full range) Resolution 0.1 degree Input Impedance 1×10⁶ ohms ± 5% shunted by 95 pF maximum Isolation Input low may be connected to chassis ground or floated up to 30 volts RMS (42 volts peak) above ground Coupling Signal may be ac or dc coupled. Low frequency 3-dB point <1 Hz in ac mode A-weighting Hardware A-weighting filter conforms to ANSI standard S1.4-1971 (R1976) ICP current Nominal 4 mA current source provided, compatible with integrated circuit piezoelectric accelerometers Output Source Band-limited, band-translated, pseudo-random, random, or impulse, or TTL "synch" signals are available on rear panel. Level is selectable between 0.7 and 0.007 volts RMS, nominal. Impedance 50Ω ±5Ω. Print/Plot Controls HP-GL plotters and HP raster dump printers directly Display General Magnitude, phase, time and math traces may be selected. Units available are: Horizontal: Hz, seconds, RPM, orders; linear or log spacing. Vertical: dBV, dBm (selectable Z), volts, volts squared, and user-defined units. Scale Linear or log magnitude scales may be selected. Full scale, dB/division, and degrees/division are user definable. Center scale user definable in phase or time traces. Math Arithmetic operations can be performed on new or recalled frequency spectra. Add, subtract, multiply, divide, integrate, differentiate and user-defined constants are provided. 1/BW is provided for Power Spectral Density (PSD) computations. Internal Memory Standard Non-volatile 2 traces, 6 states Standard Volatile 40 time records Optional Non-volatile Traces + states + (1 + 2 × time capture records) = 127 Optional Volatile 40 time records Marker Functions Single, relative, harmonic, sideband, and power cursors are provided. THD can be calculated from up to 20 harmonics. Sideband power relative to specified carrier can be calculated from up to 10 sidebands. MKR to peak, MKR to center, MKR to full scale and marker peak track are provided. General Power 100/120 Vac +5%, -10%, 48-440 Hz; 220/240 Vac +5%, -10%, 48-66 Hz Weight 15 kg (33 lb) net, 21.6 kg (47.5 lb) shipping Dimensions 335 mm W × 595 mm D × 197 mm H (13.2" × 23.4" × 7.8") HP-IB Interface Functions Implementation of IEEE Std. 488-1978 SH1, AH1, T5, TE0, L4, LE0, SR1, RL1, PP0, DC1, DT1, C0 **Important:** Input impedance is 1×10⁶ ohms ±5% shunted by 95 pF maximum. Input low may be connected to chassis ground or floated up to 30 volts RMS (42 volts peak) above ground. Maximum input is selected in 1 dB steps from +27 to -51 dBV. ## About this used unit - Warranty included - Functional verification included - Standard Calibration Upgrade Options: No Calibration Required, NIST Traceable, Z540.1 or ISO 17025 with Data, Z540.3 Guardbanding with Data. - Note that unnecessary accessories may not be included (contact Test Architect to confirm). **Please review the Manufacturer's Data Sheet to verify published specifications. Feedback on this webpage is always welcome — please reach out to your Test Architect at any time for questions or concerns. Thank you, we truly appreciate you being our customer.** ## Details - **Price:** 0.0 USD - **Vendor:** HP - **Type:** Spec An - **Tags:** Agilent, Agilent Keysight, Analyzers, Manufacturers, product_manual_group_1, Product_used, Signal, Updated Item Review ## Variants | Variant | Price | Available | |---------|-------|-----------| | None | 0.00 USD | In stock | | NIST Traceable | 0.00 USD | In stock | | NIST Traceable with Full Data | 0.00 USD | In stock | | ISO IEC 17025 Accredited | 0.00 USD | In stock | ## Images - HP 3561A Single Channel Dynamic Signal Analyzer 0.000125 Hz to 100 kHz (Pre-Owned) --- > Source: [ValueTronics](https://valuetronics.com/products/3561a-agilent-signal-analyzer-used) > Updated: 2026-05-30