Agilent/Keysight 8478A

The Agilent/Keysight 8478A is a precision coaxial thermistor mount RF detector engineered for accurate power measurements across microwave and RF frequencies. It delivers high sensitivity and linearity for both continuous wave and modulated signals, with calibration data traceable to NIST. The 8478A integrates directly with Keysight power meters - particularly the 432A and 431A - to enable high-accuracy power characterization in demanding test environments.

Technical Specifications

• Frequency range: 10 MHz to 10 GHz


• Power measurement range: 1 µW to 10 mW (with Model 431, 432, or 432A)


• Maximum peak power: 200 W


• Maximum average power: 30 mW


• Maximum energy per pulse: 10 W·µs (PRF ≥ 1 kHz); 5 W·µs (PRF < 1 kHz) Electrical


• Input impedance: 50 ohms


• Operating resistance: 200 ohms, unbalanced


• Temperature compensation: Integrated for low drift and thermal shock stability


• SWR (Standing Wave Ratio): - 10 MHz to 25 MHz: 1.75 - 25 MHz to 7 GHz: 1.30 - 7 GHz to 10 GHz: 1.50 Calibration & Physical


• Calibration factor and effective efficiency data at six frequencies, NIST-traceable


• Connector: Stainless steel Type-N male


• Weight: 140 g (5 oz)

Key Features

• Coaxial thermistor mount design optimized for RF power detection


• Low thermal drift through integrated temperature compensation


• Direct mating with standard power meter cables for seamless integration


• 50-ohm characteristic impedance ensures minimal signal corruption in typical systems


• Minimal return loss across the operating band (14 dB to 17.7 dB in core frequency bands)

Typical Applications

• Microwave and RF power verification


• Pulsed and modulated signal characterization


• Broadband power measurement from 10 MHz through 10 GHz


• Precision power monitoring in systems requiring NIST-traceable accuracy

Compatibility & Integration Designed for use with Keysight/Agilent power meters Model 431A and 432A. Operates directly with power meter cabling for measurement automation and data logging.