The Model 851B is the Display Section of the Hewlett-Packard Spectrum Analyzer; the RF Section is the Model 8551. Together, the 851/8551 provide an Analyzer which can display up to 2 Gc of spectrum. Analyzer input range is from 10 Mc to 42 Gc, its dynamic range is 60 db, its sensitivity is at least -65 dbm, its image separation is 4 Gc, and its functions are calibrated. The RF Section, which is a receiver that electronically scans the input signal, is described in a separate Operating and Service Manual. DESCRIPTION. The 851B Display Section is an oscilloscope with an unusually wide dynamic range. The display is amplitude vs frequency, and range is such that a fundamental and harmonics down as far as 60 db can be viewed simultaneously. In addition to the features offered by other good oscilloscopes - - features such as calibrated sweep times, calibrated gain, choice of synchronizing voltages, vertical and horizontal positioning, focus adjustments, and intensity variation -the 851B provides additional facilities which widen the scope of the Analyzer as an electronic tool.