HP / Agilent 5381A 80 MHZ FREQUENCY COUNTER

The HP/Agilent 5381A is a direct-counting frequency counter that measures signals from 10 Hz to 80 MHz with a 7-digit LED display. Designed for production line testing, equipment calibration, frequency monitoring, and educational use, this instrument delivers repeatable results across industrial and laboratory environments.

Technical Specifications Frequency Range: 10 Hz to 80 MHz Display: 7-digit LED readout Sensitivity:

25 mV RMS (sinewave) from 30 Hz to 20 MHz

50 mV RMS (sinewave) from 10 Hz to 80 MHz Input Characteristics: 1 MΩ impedance with 5 MHz

×10 attenuator: 200 V (dc + peak ac) DC to 40 Hz; 250 V rms 40 Hz to 1 MHz; 2.5 × 10⁷ V Hz 1 MHz to 50 MHz; 5 V rms 50 MHz to 80 MHz

Key Features

Direct counting architecture ensures straightforward operation and stable performance

Manual gate time selection supports both fast production measurements and high-resolution calibration work

External time base input via rear-panel connector enables connection of precision oscillators and permits ratio measurements

High input impedance minimizes loading effects on measured circuits

Typical Applications Production line frequency validation, radio and test equipment service and calibration, continuous frequency monitoring, and technical education.

Compatibility & Integration Introduced in the early 1970s and manufactured through the early 1980s. Agilent Technologies discontinued support for this product. Aluminum case construction.