TM 9-6625-1753-14
C1
(2) Trigger coupling for normal or delayed sweep. You can select three modes of operation with the COUPLING
(d) The normal range of the LEVEL control is 10 volts. You can extend this range to 100 volts by pulling the
switch for coupling the triggering signal.
LEVEL control into the PULL EXT 10 position.
(a) AC. Use this position for input signals with frequencies greater than 80 cycles. Because a high-pass filter is
(4) Use of the HF STAB control. When the normal seep is operating the in the recurrent mode, stable
provided in this mode, erratic triggering is prevented when positioning the trace vertically.
synchronization of high-frequency signals can be effected. This is done by rotating the HF STAB control out of its detent
(b) ACF. Use this position for input signals with frequencies greater than 10 kc. This triggering mode provides
position. Rotating the HF STAB control varies the natural frequency of the recurrent normal sweep slightly so that exact
stable triggering from a complex high-frequency waveform that contains undesirable low-frequency noise or line-frequency
submultiples of the trigger frequency can be selected.
components.
b. Triggering Instructions for Normal Sweep.
(c) DC. Use this position for waveforms that change slowly (low-frequency input signals).
(3) Use of SLOPE switch and LEVEL control. You use the SLOPE switch and LEVEL control to start the trace at
Note. Review the general triggering information in a above before proceeding with the following instructions.
any selected point on the triggering waveform. The SLOPE switch allows the triggering to be selected on either the rising or
the falling portion of the waveform. The LEVEL control sets the dc level at which triggering takes place.
(1)
Perform the oscilloscope staring procedure (par. 2-7).
(a) Figure 2-1 illustrates how the SLOPE switch is used to start the sweep on the rising or falling portions of the
(2)
Connect the probe to the signal source. (Connect both probes for dual-trace operation.)
waveform. Remember, this has nothing to do with the polarity of the waveform. You use the setting that best displays the
(3)
Connect the external trigger source to the EXT TRIG connector if external trigger is used.
desired portion of the waveform. With the SLOPE switch set at "+", triggering would start the sweep at point A, but with the
(4)
Set the dual trace plug-in controls as required (par. 2-9).
SLOPE switch set at "-", triggering would start the sweep at point B.
(5)
Set other controls as follows:
(b) Figure 2-2 illustrates how you can select the desired triggering point, using the SLOPE switch and the LEVEL
control. The horizontal lines represent the dc level set by the LEVEL control. Notice how the setting of the SLOPE switch
DISPLAY LOGIC
NORM
determines the point on the waveform where triggering occurs.
(c) If the COUPLING switch is set at DC, you can offset any dc component of the triggering waveform by
NORMAL AND DELAYING TRIGGERING SLOPE
As required by triggering mode in use, par. a(3).
adjusting the LEVEL control. For example, if the waveform has a negative dc component, the LEVEL control must be set
NORMAL AND DELAYING TRIGGERING COUPLING
AC, ACF, or DC, depending on conditions, par. a above.
positive by the same amount to give equivalent triggering as that obtained with a zero setting on a waveform without a dc
NORMAL AND DELAYING TRIGGERING LEVEL
Fully clockwise.
component.
HF STAB
NORM
TIME/DIV
Any setting that will display at least 1 cycle of the waveform.
(6) Rotate the NORMAL AND DELAYING TRIGGERING LEVEL control until the trace appears.
(7) Set the TIME/DIV switch to display as many cycles of the waveform as desired.
(8) Adjust the NORMAL AND DELAYING TRIGGERING LEVEL control and set the SLOPE switch + or - position for
trigger source used) until the desired portion of the waveform is displayed (fig. 2-2).
(9) By setting the sweep faster than the period of the waveform, it is possible to display just the first part of the
waveform. Try various settings of the TIME/DIV, NORMAL AND DELAYING TRIGGERING LEVEL, and NORMAL AND
DELAYING TRIGGERING SLOPE controls to obtain the best presentation.
(10) If the trace is not stable with the HF STAB control in the NORM position, rotate the control until the trace
stabilizes.
c. Use of the PULL X10 Switch. Pull out the PULL X10 switch to magnify the horizontal amplitude of the display 10
times. Adjust the horizontal POSITION control as required to bring the desire portion into view.
d. Triggering Instructions for Delaying Sweep.
Note. Review the general triggering information in paragraph a above before proceeding with the following:
(1) Triggered-strobe operation. When the DISPLAY LOGIC switch is in the TRIG-STROBE position, the normal seep
will display the trace, and the strobe circuit (controlled by the delaying sweep) will brighten the trace. If the delaying sweep is
faster than the normal sweep speed, only part of the trace is brightened. If the delaying sweep is very much faster the
brightened portion of the trace is only a spot, which makes a useful marker when the delaying sweep is used for time
measurements (par. 2-12 below). To operated tin the triggered-strobe mode:
(b) Connect the probe to the signal source. (Connect both probes for dual-trace operation.)
(c) Set the DISPLAY LOGIC switch to the TRIG-STROBE position.
Figure 2-1. Use of the SLOPE switch.
Figure 2-2. Use of triggering LEVEL and triggering
SLOPE controls.
(d) Use the procedures in paragraph b to stabilize the normal seep which displays the trace.
(e) To adjust the length of the brightened portion of the trace, pull out the DELAYED SWEEP-PULL TO UNLOCK
switch and rotate it. Increasing the delaying sweep speed shortens the brightened portion; decreasing the sweep speed
lengthens it.
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