Description
HP 3581A Wave Analyzer 15 Hz to 50 kHz AFC Audio Spectrum Hewlett-Packard
The Hewlett-Packard 3581A is a benchtop wave analyzer covering 15 Hz to 50 kHz, designed to resolve and measure the amplitude and frequency of individual spectral components in a signal. A key feature is its Automatic Frequency Control (AFC) circuit — labeled on the front panel as AFC/UNLOCK — which locks onto a drifting signal source and maintains stable, accurate measurements even when the input frequency is not perfectly steady. The instrument presents amplitude readings on a large analog meter calibrated in both Decibels and RMS Volts.
Specifications & What's Included
- Model: HP / Hewlett-Packard 3581A Wave Analyzer
- Frequency range: 15 Hz to 50 kHz
- Display: Analog meter — Decibels (upper arc) and RMS Volts (lower arc) scales
- Frequency display: Hz readout window with AFC / UNLOCK status indicator
- AFC circuit: locks to drifting signals for stable amplitude and frequency measurement
- Front-panel controls: Frequency tuning, Resolution Bandwidth, Freq Span, Sweep Time, Sweep Mode
- Front-panel level controls: Amplitude Ref Level, Input Sensitivity
- Input connectors: banana/binding-post jacks on front panel
- Rear panel: multiple BNC connectors for input/output connections; IEC AC power inlet
- Form factor: benchtop/portable with integrated carry handle
- Unit only — no cables, accessories, or manual confirmed included
Applications
The HP 3581A was designed for audio-frequency and low-frequency spectral analysis — the frequency range from 15 Hz to 50 kHz covers the full audio band and just beyond. It was widely used in electronics calibration labs, audio equipment design and testing, acoustic and vibration analysis, and product development work where precise measurement of individual frequency components (rather than a broadband reading) was needed. The selective nature of a wave analyzer — as opposed to a general oscilloscope or voltmeter — lets the user tune to a specific frequency and measure its amplitude with high rejection of other signals, making it valuable for noise and distortion analysis, harmonic measurement, and filter characterization. Instruments of this type date from the 1970s–1980s era of HP's analog test equipment line, when benchtop wave analyzers like the 3581A were standard tools in RF, audio, and calibration labs before digital FFT analyzers became prevalent. They remain useful today for low-frequency work and are sought after in the vintage test equipment community for their build quality and accuracy.
This HP 3581A Wave Analyzer came to us from a retiring electrical engineer who had used it in his calibration and product development lab. It has not been powered up or tested at our facility, but it comes directly from a working professional environment where it was actively in service. The unit appears to be in good cosmetic condition consistent with normal bench use — the front panel, meter face, and controls all look intact and undamaged in our photos. The rear panel BNC connectors and labeling appear clean. Please review our full photo set carefully, and contact us with any questions before purchasing.
Warranty Information
Additional Information
Brand: |
HP |
Model: |
3581A |
MPN: |
3581A |
Type: |
Wave Analyzer |
SKU: |
24926 |
Frequency Range: |
15 Hz to 50 kHz |
Measurement Type: |
Amplitude and Frequency (Spectral Analysis) |
Display Type: |
Analog meter — dB and RMS Volts scale |
Frequency Display: |
Hz readout with AFC / UNLOCK indicator |
AFC / AFT: |
Yes — automatic frequency control circuit included |
Controls: |
Resolution Bandwidth, Freq Span, Sweep Time, Sweep Mode |
Input Sensitivity: |
Variable — front-panel Input Sensitivity control |
Amplitude Reference Level: |
Front-panel Amplitude Ref Level control |
Connector Types: |
BNC (rear panel inputs/outputs), banana jack (front input) |
Form Factor: |
Benchtop / Portable |
Seller Notes: |
Unit only — no accessories, cables, or manual confirmed included. |
Country/Region of Manufacture: |
United States |
Condition Notes: |
This HP 3581A Wave Analyzer came from a retiring engineer's calibration lab. Not tested at our facility, but pulled from an active working environment. Cosmetically good — panel, meter, and controls appear intact. |
California Prop 65 Warning: |
WARNING: This product can expose you to chemicals including lead and lead compounds, and DEHP (a phthalate), which are known to the State of California to cause cancer and birth defects or other reproductive harm. Go to P65Warnings.ca.gov |