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 relationships to each other, but
inverted signals can be used.
3 Set CH1 and CH2 AC-GND-DC switches to
AC.
4. Set the MODE switch to ALT or CHOP.
5. Set SOURCE switch to CH1 and adjust
controls as described in the procedure for
synchronizing waveforms.
6. Adjust CH1 and CH2 POSITION controls to
superimpose the waveforms directly over each
other.
7. Adjust CH1 and CH2 vertical sensitivity con-
trols (VOLTS/DIV and VARIABLE) so that the
waveforms are as large as possible without ex-
ceeding the limits of the scale, and so that
both waveforms are exactly the same height.
8. Now, set the Mode switch to ADD and the
CH2 polarity switch to the PULL INVERT posi-
tion. (If one waveform is inverted in
relationships to the other, use the normal CH2
polarity.)
Adjust the vertical sensitivity control (CH2
V A R I A B L E ) for the minimum remaining
waveform. Any waveform that remains equals
distortions; 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 remaining on the screen.
Gated Ringing Circuit (burst circuit)
The circuit and waveform of Fig.
11
are shown to
demonstrate the type of circuit in which the
dual-trace oscilloscope is effective both in design
and troubleshooting applications.
Fig.
11
shows a burst circuit. The basic settings
are identical to those of in Fig. 5.
Waveform EA is the reference waveform and is
applied to CH1 input. All other waveforms are
sampled at CH2 and compared to the reference
waveform of CH
1.
The frequency burst signal can
be examined more closely either by increasing the
sweep time per division to
0 . 5
ms per division or by
pulling the POSITION control to obtain
10
times magnification. This control can then be
rotated as desire to center the desired waveform
information on the oscilloscope screen.
Delay Line Test:
The dual-trace feature of the oscilloscope can also
be used to determine the delay times of transmis-
sion type delay lines as well as ultrasonic type
delay lines. The input pulse can be used to trigger
or synchronized the C H
1
display and the delay line
output can be observed on CM2. The interval
between repetitive pulses should be large com-
pared to the delay time to be observed. In addition
to determining delay time, the pulse distortion in-
herent in the delay line can be determined by ex-
amination of the delay pulse observed on CH2
waveform display.
Fig.
12
shows the typical oscilloscope settings as
well as the basic test circuit. Typical input and out-
put waveforms are shown on the oscilloscope dis-
play. Any pulse stretching and ripple can be
observed and evaluated. The results of modifying
the input and output terminations can be observed
directly.
A common application of the delay line checks is
found in color television receivers to check the " Y "
delay line employed in the video amplifier section.
The input waveform and output waveform are com-
pared for delay time, using the horizontal sync
14
Fig.
11
Gated ringing circuit and waveforms
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