1. Apply the type of signal normally encountered in the
amplifier under test.
2. Connect CH1 probe to the input of the amplifier and
CH2 probe to the output of the amplifier. It is
preferable if the two signals are not inverted in
with respect to each other, but inverted signals can be
used.
3. Set CH1 and CH2 DC-GND-AC switches to AC.
4. Set the MODE switch to DUAL.
5. Set SYNC SLOPE switch to CH1 and adjust controls
as described in the procedure for synchronizing
waveforms.
6. Adjust CH1 and CH2 POSITION controls to superim-
pose the waveforms directly over each other.
7. Adjust CH1 and CH2 vertical sensitivity controls
(VOLTS/DIV and VARIABLE) so that the waveforms
are as large as possible without exceeding the limits of
the scale, and so that both waveforms are exactly the
same height.
8. Now. set the MODE switch to S U B position (if one
waveform is inverted with respect to the other, use the
ADD position).
Adjust the fine vertical sensitivity control (CH2
VARIABLE) for the minimum remaining waveform; if
the two waveforms are exactly the same amplitude
and same waveform and there is no distortion, the
waveforms will cancel and there will be only a straight
horizontal line will remain on the screen.
Gated Ringing Circuit(burst circuit):
Fig. 8 shows a burst circuit. The basic settings of con-
trol knobs are the same as those in Fig. 4. The waveform A
is the reference waveform and is applied to CH1 input. All
other waveforms are sampled at CH2 and compared to the
reference waveform of CH1. The burst signal can be ex-
amined more closely either by increasing the sweep time or
by pulling the < • POSITION control to obtain 5 times
magnification.
Delay Line Test:
The dual-trace feature of the oscilloscope can also be
used to determine the delay times of transmission type delay
lines as well as ultrasonic type delay lines. The output of
delay lines is observed on CH2 while being synchronized
with the input pulse of CH1. The interval between pulses
should be large compared to the delay time to be observed.
In addition, to determining delay time, the pulse distortion
inherent in the delay line can be determined by examination
of the delay pulse observed on CH2 waveform display.
Fig. 9 shows the typical oscilloscope settings as well
as the basic test circuit. Typical input and output waveforms
are shown on the oscilloscope display. This delay line
checking method may also be used for color TV receivers.
Fig. 10 shows the oscilloscope settings and typical circuit
connections to check the " Y " delay line employed in the
video amplifier section. The input waveform and output
Fig. 8. Gated ringing circuit and waveforms
P U L S E
G E N
AC D U A L A C
I N P U T
U L T R A S O N I C
D E L A Y L I N E
( 5 / j S e c )
5 0 0 0 P P S
l f i S e c P U L S E W I D T H
Fig. 9. Delay line measurements
12
O U T P U T
