The HP/Keysight 8971B/C noise figure test set allows the 8970B to make noise figure measurements over an extended frequency range. Careful design and high-performance components, including a stable YIG filter, allow broadband single-sideband measurements from 10 MHz to 18 GHz (B-version) or 26.5 GHz (C-version) with a single calibration and sweep. A low-noise preamplifier built into the noise figure test set lowers the second-stage noise figure, thereby reducing a major source of measurement uncertainty. A second advantage is that for calibration a low ENR noise source can be used, the same as for measurements. Measurement modes in the 8970B allow for double down-conversion using the 8971B/C as the second downconverter. The noise figure test-set or down converter is controlled by the HP8970B via a dedicated GPIB interface (SIB).