The Agilent/Keysight 85081A High Impedance Input Module is an accessory for the 8508A Vector Voltmeter that provides high input impedance measurement capability for precise voltage characterization in sensitive circuits. By minimizing circuit loading, the module enables accurate measurements where disturbance to the device under test must be kept minimal. Operating from 100 kHz to 1 GHz, the 85081A forms a two-channel receiver system with the 8508A mainframe for high-frequency voltage and phase measurements across a dynamic range of 10 µV to 1 V.
Technical Specifications
• Frequency range: 100 kHz to 1 GHz
• Measurement levels: 10 µV to 1 V
• Maximum input: 2 VAC Peak, ±50 VDC
• Input impedance: High impedance design
• Sensitivity: 10 µV (narrowband measuring technique)
• Operating temperature: 0 to 55 °C (specifications warranted)
– Key Features
• Two high-impedance probe inputs for direct signal connection
• Narrowband measuring technique for enhanced sensitivity and selectivity
• Direct integration with 8508A Vector Voltmeter mainframe
• Minimal circuit loading for accurate measurements in high-impedance networks
– Typical Applications
• High-impedance voltage measurements in sensitive RF and analog circuits
• Phase measurement characterization at microwave frequencies
• 50-ohm Type N coaxial system measurements (with 11570A kit)
• Low-level signal detection and analysis from 100 kHz to 1 GHz
– Compatibility & Integration
The 85081A connects directly to the Agilent/Keysight 8508A Vector Voltmeter and is not sold separately. It is classified as an obsolete product no longer in active production, though repair and calibration services may remain available. ESD protection measures are required during handling to prevent component damage.
