TB 9-6625-2088-24
9. Symmetry and VCG Null
a. Performance Check
(1) Connect oscilloscope to FUNCTION OUT using 50
feedthrough termination.
(2) Turn frequency dial to .02 and adjust ATTENUATION VERNIER control for a
5 V p-p indication on oscilloscope.
(3) Adjust oscilloscope to display 1 cycle at 5 major divisions (horizontal).
(4) Using a shorting lead, alternately short and open VCG IN terminal while
observing oscilloscope display. If waveform shifts horizontally, perform b (1) below.
(5) Disconnect oscilloscope from TI and connect TI to frequency counter.
(6) Set FREQ/PERIOD MULTI (Hz/s) switch to 100K and VERNIER control
fully ccw. If frequency counter does not indicate 5 ms or greater, perform b (2) below.
(7) Adjust frequency counter to measure symmetry of square wave. If T1 is not
NOTE
To measure T1, set frequency counter INPUT A slope switch to
+ (positive) and INPUT B slope switch to - (negative). Reverse
slope switches to measure T2. FUNCTION to TIME INT.
Figure 1. Symmetry waveform.
(8) Position controls as listed in (a) through (c) below:
(a) FREQ/PERIOD MULTI (Hz/s) switch to 1 K.
(b) Frequency dial to 2.0.
(c) FREQ/PERIOD MULTI (Hz/s) VERNIER control fully cw.