GENERAL DESCRIPTION The Model 301 Oscilloscope is designed for use with the Cushman Models CE-3 and CE-7 FM Communications Monitors. The Oscilloscope enables the user to visually examine the exact modulation delivered by the transmitter. Any abnormal conditions such as unbalanced modulation, pulses from the power supply, unusual clipping, and other problems are immediately apparent so that appropriate repairs can be made. The Model 301 has an automatic sync circuit to lock on and precisely display waveforms. Vertical display is calibrated to show deviation on any one of three ranges: ±1 5, ±5. and ±15 kHz. Front panel switches permit an external vertical signal input while using the internal sweep. External signals may also be connected to the horizontal input. Thus, the oscilloscope can be used independently of the monitoring function for routine testing, trouble shooting, displaying Lissajous patterns, etc. The Model 301 Oscilloscope Plug-In has the standard oscilloscope front-panel controls, most of which are self-explanatory. (See Figure 2-1 ) A focus control, intensity control, and astigmatism control are provided to ensure a clean trace on the face of the CRT. Vertical and horizontal position controls are provided to position the display and set the display with respect to the zero reference line on the scope graticule when the CE-3 function switch is in the CAL. position. The lever switch directly below the CRT is a range switch for vertical display of deviation and is directly calibrated in ±1.5, ±5. and ±15 kHz of deviation The scope circuit is dc-coupled and the displayed deviation will shift up or down if the transmitter under test is off frequency. Separate external inputs to the vertical or horizontal amplifiers which drive the CRT are provided. Separate toggle switches permit selection of either internal or external signals in conjunction with the external input connectors The Model 301 sweep speeds can be adjusted with a sweep-speed switch and vernier control: it is normally unnecessary to adjust the sweep speed to lock the audio waveform being displayed. The Model 301 incorporates an automatic sync control which provides instant lock on any signal exceeding one division in peak-to-peak amplitude An external-vertical-gain control permits artenuation of signals applied to the external vertical input The Model 301 Oscilloscope is removed by turning •-re arge slotted knob on the rear panel of the monitor cc_~terclockwise When the locking shaft has been dis-ervgaged from the plug-in. pushing the knob inward * cause the plug-in connector to separate The Model 301 can then be easily removed.