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In the C H O P mode, the s w e e p is chopped at an approximate 5 0 kHz rate and s w i t c h e d
between C H 1 and C H 2 . Note that in the C H O P mode of operation, the trigger source
becomes the chopping signal itself, making waveform observation impossible. Use A L T
mode instead in s u c h c a s e s , or select a trigger S O U R C E of C H 1 or C H 2 .
If no trace is obtainable, refer to the following T R I G G E R I N G procedures.
4 . After setting the S O U R C E s w i t c h , adjust the S L O P E control.
The display on the screen will probably be unsynchronized. Refer to T R I G G E R I N G proce-
dure below for adjusting synchronization and s w e e p speed to obtain a stable display
showing the desired number of w a v e f o r m .
T R I G G E R I N G
T h e input signal must be properly triggered for stable w a v e f o r m observation. T R I G G E R -
ING is possible the input signal INTernally to create a trigger or with an EXTernally provid-
ed signal of timing relationship to the observed signal, appliying s u c h a signal to the E X T
T R I G INPUT jack.
T h e S O U R C E s w i t c h selects the input signal that is to be used to trigger the s w e e p , w i t h
INT s y n c possibilities ( C H 1 , C H 2 , LINE) and E X T s y n c possibility.
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Internal S y n c
W h e n the S O U R C E selection is in NORM and INT ( C H 1 or C H 2 ) , the input signal is con-
nected to the internal trigger circuit. In this position, a part of the input signal fed to the
INPUT ® or © jack is applied from the vertical amplifier to the trigger circuit to cause
the trigger signal triggered with the input signal to drive the s w e e p .
W h e n the V or Y MODE selection is in A L T , the A L T position is very convenient for m e a s -
uring the time duration of the w a v e f o r m . However, for phase or timing comparisons be-
tween the channel 1 and channel 2 w a v e f o r m s , both traces must be triggered by the same
s y n c signal.
W h e n the S O U R C E selection is in NORM and INT ( C H 1 ) , the input signal at the channel
1 INPUT (8) jack becomes trigger regardless of the position of V or Y M O D E . W h e n the
S O U R C E selection is in NORM and INT ( C H 2 ) , the input signal at the channel 2 INPUT
© jack becomes trigger regardless of the position of V or Y M O D E . W h e n the S O U R C E
selection in LINE, the A C line voltage powering the oscilloscope is used as s y n c triggering.
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External Sync
W h e n the S O U R C E selection is in NORM and E X T , the input signal at the E X T T R I G INPUT
© jack becomes the trigger. T h i s signal must have a time or frequency relationship to
the signal being observed to synchronize the display. External s y n c is prefered for w a v e -
form observation in many applications. For example, Fig. 6 s h o w s that the s w e e p circuit
is driven by the gate signal w h e n the gate signal in the burst signal is applied to the E X T
T R I G INPUT jack. Fig. 6 also s h o w s the input/output signals, where the burst signal gener-
ated from the signal is applied to the instrument under test. T h u s , accurate triggering can
be achieved without regard to the input signal fed to the INPUT (8) or @ jack so that no
further triggering is required even w h e n the input signal is varied.
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