The 8555A RF Tuning Section Plug-in is the top-end tuning section for Hewlett-Packard's high performance modular Spectrum Analyzer family. When added to a system package, it will offer absolute amplitude calibration capabilities from -125 dBm to +10 dBm over a frequency range of 10MHz to 18GHz with fundamental and harmonic mixing. Optional mixers can extend its frequency coverage to 40 GHz. Sensitivities to -125 dBm (125 nV) and resolution to 100Hz with bandwidth ranges from 100Hz to 300kHz in 1-3-10 sequence. These high resolution measurements are made possible in part by the 8555A's automatic tuning stabilization (phase-lock) feature, which allows for narrow frequency range scanning with a minimum of display jitter.