TM 11-6625-2925-10/T0 33A1-10-242-1
AC. The AC pushbutton blocks the dc component of a thecomplex waveform. Line triggering cannot be used when
trigger signal. Signals with low-frequency components belowoperating in the HF SYNC triggering mode.
about 30 hertz are attenuated. In general, ac coupling can be
used for most applications. However, if the signal containsEXT. The EXT pushbutton connects the signal from the MAIN
unwanted frequency components or if the sweep is to beTRIG IN connector to the trigger circuit. The external signal
triggered at a low repetition rate or dc level, one must be time-related to the displayof -he othered waveform for a stable
COUPLING switch positions will provide a better display.display. An external trigger signal can be used to provide a
triggered display when the internal signal is too low in
AC LF REJ. The AC LF REJ pushbutton rejects dc, andamplitude for correct triggering, or contains signal components
attenuates low-frequency trigger signals below about 30on which triggering is not desired. It is also useful when signal
kilohertz. Therefore, the sweep is triggered only bytracing the higher-in amplifiers, phase-shift networks, wave-shaping
frequency components of the trigger signal. This position circuits, isetc. The signal from a single point in the circuit can
particularly useful for providing stable triggering if the be connected triggerto the MAIN TRIG IN connector through a probe
signal contains line-frequency components. Also, the ACor cable. T LFhe sweep is then triggered by the same signal at all
REJ position provides the best alternate mode vertical times displayand allowss amplitude, time relationship, or waveshape
at fast sweep rates when comparing two or more unrelatedchanges of signals at various points in the circuit to be
signals.examined without resetting the MAIN TRIGGERING controls.
AC HF REJ. T he AC HF REJ pushbutton passes all lowEXT ¸ 10. The EXT + 10 pushbutton operates the same as
frequency signals between about 30 hertz and 50 kilohertzdescribed for EX.T except that the external signal is attenuated.
Dc is rejected and signals outside the above range areAttenuation of high-amplitude external trigger signals is
attenuated. When triggering from complex waveforms, thisdesirable to increase the effective range of the LEVEL control.
position is useful to provide a stable display of the low-
frequency components. AC HF REJ Coupling should not Input Impedancebe
used when operating in the HF SYNC triggering mode.
The input impedance of the MAIN TRIG IN and DLY'D TRIG IN
OC. The DC pushbutton can be used to provide stableconnectors may be selected by the front-panel TERM switch.
triggering from low-frequency signals which would be
attenuated in the other modes. It can also be used to triggerIN -1MW . The 1 MQ position is suitable for most low and
the sweep when the trigger signal reaches a dc levemedium-frequencyl set by applications or when using a 10X probe.
the LEVEL control. When using internal triggering, the The setting1 ME, position provide a high input impedance for
of the Amplifier plug-in unit Position control affects minimum loading on the trigger signal source.the
triggering point.
OUT 50W . The 50,W position is recommended for high
Main Trigger Source
frequency applications requiring maximum overall bandwidth.
The 50 ohm termination should be used when externally
The Main Triggering SOURCE pushbutton switches selecttriggering from a 50 ohm system. the
source of the trigger signal which is connected to the main
trigger circuits.
Trigger Slope
INT. The INT pushbutton connects the trigger signal from the
The Main Triggering SLOPE switch (concentric with the Main
Amplifier plug-in unit. Further selection of the internal triggerTriggering LEVEL control) determines whether the trigger
signal may be provided by the Amplifier plug-in unit orcircuit responds on the positive-going or negative going portion
oscilloscope; see the instruction manuals for these
of the trigger signal. The trigger slope cannot be selected
instruments for more information. For most applications, thewhen operating in the high-frequency synchronization mode.
internal source can be used. However, some applications
When the SLOPE switch is in the (+) (positive going) position,
require special triggering which cannot be obtained in the INTthe display start on the positive-going portion of the waveform;
position. In such cases, the LINE or EXT positions of thein the (-) (negative-going) position, the display starts on the
SOURCE switches must be used.negative-going portion of the waveform (see figure2-4). When
several cycles of a signal appear in the display, the setting of
LINE. The LINE pushbutton connects a sample of the power-
the SLOPE switch is often unimportant. However, if only a
line voltage from the oscilloscope to the trigger circuit. Linecertain portion of a cycle is
triggering is useful when the input signal is time related
(multiple or submultiple) to the line frequency. It is also useful
for providing a stable display of a line-frequency component in
2-9 |
ACEC
