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The 222A is a general-purpose instrument providing variable repetition rate; variable pulse delay, width, and amplitude; and positive or negative pulses with a rise and fall time of less than 4 nanoseconds. This model 222A output impedance matches an external system of 50 ohms on all ranges, thus minimizing error-producing reflections. The maximum usable output pulse amplitude is approximately 12 V into an open circuit or 10 V into 50 ohms, and may be set at less than 50 mV by using the vernier and the lowest amplitude range. A duty cycle of 50% may be set for frequencies of 100 Hz to 10 MHz, providing a square wafer output. Pulses may be obtained from this unit using the manual pushbutton or at a rate of dc to 10 MHz using an external trigger source of positive or negative 0.5 V peak, or from 10 Hz to 10 MHz using the internal rate generator.