General Description The Type TU-7 Plug-In Test Unit is a versatile single-unit calibration aid for use with all Tektronix 530-, 540-, or 550-Series Oscilloscopes using 1-series or ietter-series vertical plug-in units. The Type TU-7 is the only plug-in unit required for calibrating the oscilloscope.* An input connector on the front panel of the Type TU-7 permits application of various external signals for use in the calibration procedure. The self-contained unit also generates fast-rise pulses for checking risetime and adjusting transient response of the oscilloscope vertical amplifier. The T/pe TU-7 permits checking the regulation limits of the power supplies. In addition, the unit provides a quick check of the oscilloscope alternate sync pulse and chopped blanking circuitry. For oscilloscopes capable of displaying two time-base signals alternately, the Type TU-7 checks the ability of the alternate-sweep switching circuitry to lock the channels of a dual-trace plug-in unit to the time bases of the oscilloscope.