Features:

• High accuracy even in routine power measurements
• Temperature compensated for low drift
• Measures microwave power as low as one microwatt
• Shows calibration factor and effective efficiency at 16 frequencies
• Frequency Range: 10 MHz to 18 GHz
• Maximum SWR: 10 MHz to 30 MHz 1.75; 30 MHz to 100 MHz 1.35; 100 MHz to 1 GHz 1.10; 1 GHz to 12.4 GHz 1.35; 12.4 GHz to 18 GHz 1.60
• 1 year standard warranty

The Keysight 8478B provides high efficiency and good radio frequency (RF) match. Used in conjunction with the N432A or 432A power meters they provide high accuracy even in routine power measurements. These thermistor mounts are temperature compensated for low drift, even in the presence of thermal shocks, permitting measurement of microwave power as low as one microwatt. Each mount contains data showing calibration factor and effective efficiency at six frequencies, directly traceable to the U.S. National Institute Standards and Technology (NIST) at those frequencies where NIST provides calibration service.

Coaxial Thermistor Mount (10 MHz to 18 GHz)

The Keysight Model 8478B Coaxial Thermistor Mount is designed to measure microwave power from 1μW to 10mW. The design of the mount minimizes adverse effects from environmental temperature changes during measurement. For increased measurement accuracy, Effective Efficiency and Calibration Factor are measured for each mount at selected frequencies across the operating range; the results are marked on the label of the instrument.

The Model 8478B can be used over the 10MHz to 18GHz frequency range. Throughout the range, the mount terminates the coaxial input in a 50-ohm impedance and has an SWR of not more than 1.75 without external tuning.

Each mount contains two series pairs of thermistors, which are matched to cancel the effects of drift with ambient temperature change. Thermal stability is accomplished by mounting the leads of all four thermistors on a common thermal conductor to ensure a common thermal environment. This conductor is thermally insulated from the main body of the mount so the thermal noise or shocks applied externally to the mount, such as those from handling the mount manually, cannot significantly penetrate to disturb the thermistor. This thermal immunity enables the thermistors to be used in the measurement of microwave power down to the microwatt region.