Agilent/Keysight 8508A

The Agilent/Keysight 8508A is a fully automatic tuned vector voltmeter for precise RF voltage and phase measurements across a broad frequency spectrum. It employs narrowband measuring technique to deliver dynamic range exceeding 90 dB and sensitivity of 10 µV, enabling accurate characterization of RF components and systems.

– Technical Specifications

Frequency Coverage: Two interchangeable input modules provide flexible frequency operation. The HP 85081B standard module covers 100 kHz to 1 GHz via high-impedance probe inputs. The HP 85082A module (Option 050) extends range to 300 kHz to 2 GHz with dual 50 Ω Type-N connectors.

Measurement Range & Resolution:
• Phase measurement: ±180 degrees with 0.1 degree resolution minimum
• Maximum input: 2 V peak AC (10 mV to 300 µV depending on frequency band with 85081B; +16 dBm with 85082A)
• B-channel noise floor: 10 µV (–87 dBm)
• Dynamic range: >90 dB

Accuracy (85081B):
• Absolute magnitude: ±0.3 dB (1–100 MHz), improving to ±0.2 dB ratio accuracy in same band
• Ratio magnitude: ±0.6 dB (300 MHz–1 GHz)
• Input crosstalk: >100 dB (1–500 MHz), >80 dB (500 MHz–1 GHz)

Input Protection:
• DC offset rating: ±50 V

– Key Features

• Two-channel simultaneous RF voltage and phase difference measurement
• Phase distortion and electrical length characterization
• Signal tracing capability with sub-microvolt sensitivity
• Built-in network analysis procedures for component characterization
• Impedance measurement functionality
• Interchangeable input modules for application-specific configurations

– Typical Applications

• RF component testing and verification
• Network analysis of passive and active circuits
• Phase relationship measurements in multi-channel systems
• Small-signal detection and characterization
• Transmission line and filter analysis

– Compatibility & Integration

The 8508A accepts HP 85081B (high-impedance, 100 kHz–1 GHz) and HP 85082A (50 Ω, 300 kHz–2 GHz) input modules, allowing reconfiguration for different impedance environments and frequency requirements without instrument replacement.