The 8487A thermocouple power sensor is designed for use with the EPM series, EPM-P series, 70100A, E1416A and the 435A/B, 436A, 437A/B, and 438A power meters. It operates from 50 MHz to 50 GHz at levels from -30 to +20 dBm with exceptional accuracy and stability. The 8487A has extremely low SWR and is traceable to the U.S. National Institute of Standards and Technology (NIST). A calibration port is included with the above power meters for calibration with the power sensor. This calibration provides traceability to NIST, and it eliminates the uncertainties due to temperature changes and the variance in making measurements with different meter/sensor combinations. A coaxial adapter is supplied to allow connection to the power meter 50 MHz reference output.