The HP Model 140B is a general purpose plug-in Oscilloscope. The deflection amplifiers are of the plug-in type and the Oscilloscope contains only the power supply, calibration, and CRT circuits. The plug-in amplifiers operate directly into the CRT, therefore the Oscilloscope characteristics depend upon the plug-ins used. Presently available plug-ins make possible high sensitivity, wide bandwidth, and single, dual, or four trace measurements in combination with normal, single, or delayed sweeps. Double-sized plug-ins are also available for special applications such as time domain reflectometry, swept frequency indication, and spectrum analysis. 1-3. The Model 140B provides power for the plug-ins and line-frequency square wave calibrating voltages of 10 volts and 1 volt peak-to-peak which are available on the front panel. The primary power switch and all CRT controls are on the Model 140B front panel, and the terminals and switch for Z-axis modulation are on the rear panel. 1-4. CATHODE-RAY TUBE. 1-5. The Model 140B has an internal graticule CRT that eliminates parallax error when observing the display. The CRT is equipped with a nonglare safety face plate.