Agilent/Keysight 478A

The Agilent/Keysight 478A is a coaxial thermistor mount for precision microwave power measurement across the 10 MHz to 10 GHz band. Engineered for use with Keysight 431 and 432 power meters, it delivers accurate readings from 1 µW to 10 mW with 50 Ohm impedance and temperature-compensated performance. The mount handles peak power to 200 W and average power to 30 mW, with maximum energy per pulse of 10 W·µs (PRF ≥ 1 kHz) or 5 W·µs (PRF < 1 kHz). Each unit is individually calibrated with NIST-traceable calibration factors and effective efficiency data marked on the instrument label. Operating resistance is 200 Ohms ± 1%. The Type-N male connector mates with standard MIL-C-71 or MIL-C-39012 female connectors per IEEE STD 287. Standing wave ratio performance ranges from 1.75 (10–25 MHz) to 1.30 (25 MHz–7 GHz) to 1.50 (7–10 GHz). Temperature compensation minimizes drift under varying environmental conditions and thermal stress. Optional configurations extend frequency coverage downward to 100 kHz or 1 MHz with modified SWR characteristics. The unit weighs 140 g net.