The Agilent/Keysight 85081A is a high-impedance probe input module that extends the measurement capabilities of the HP 8508A Vector Voltmeter mainframe. It provides two independent probe inputs for precise RF voltage and phase measurements across the 100 kHz to 1 GHz frequency range.
This module delivers a dynamic range exceeding 90 dB with sensitivity down to 10 µV, enabling measurements of small signals in demanding RF environments. The input level range spans 10 µV to 1 V, accommodating both weak and moderate signal levels. Phase measurements are resolved to 0.1 degrees across a ±180 degree range, supporting accurate phase characterization in circuit analysis and calibration workflows.
Designed for in-circuit measurement scenarios, the 85081A facilitates direct probing of RF nodes without requiring signal extraction or additional conditioning. Engineers working with vector voltmeter systems benefit from the module’s ability to simultaneously measure amplitude and phase relationships across complex networks.
Technical Specifications
• Frequency Range: 100 kHz to 1 GHz
• Input Level Range: 10 µV to 1 V
• Input Impedance: High-impedance probe inputs
• Number of Probe Inputs: Two
• Dynamic Range: Over 90 dB
• Sensitivity: 10 µV
• Phase Measurement Resolution: 0.1 degrees
• Phase Measurement Range: +180 to −180 degrees
– Key Features
• Dual high-impedance probe channels for simultaneous measurements
• Sensitivity adequate for micro-volt-level signal detection
• Phase resolution supporting fine tuning and circuit characterization
• In-circuit measurement capability minimizes system perturbation
– Typical Applications
• RF circuit analysis and impedance characterization
• Phase measurement and delay quantification
• Network calibration and tuning verification
• Small-signal detection in microwave circuits
– Compatibility & Integration
The 85081A operates exclusively as a plug-in module for the HP 8508A Vector Voltmeter mainframe or the HP 70138A MMS Vector Voltmeter Module. Standalone operation is not supported. Operating and Service Manual (HP 85081-90000) and Microfiche Operating and Service Manual (HP 85081-90001) are available.
