Tektronix 535A, Instruction Manual

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Operating Instructions —Type 535A
ing waveform is passed to produce the stable triggering
that you require. In all other respects the AC Low Fre­
quency Reject triggering mode is identical to the AC mode.
High Frequency Synchronization Mode
The
High Frequency Synchronization Mode permits stable
displays of waveforms with frequencies higher than approxi­
mately 5 mc. Stability of the display is adjusted with the
STABILITY control. The TRIGGERING LEVEL control is not
used. To use the High Frequency Synchronization Mode,
place the TRIGGERING MODE switch in the HF SYNC posi­
tion. Rotate the STABILITY control clockwise until a trace
appears. Continue to adjust the STABILITY control until a
stable display is obtained.
Although the synchronization signal source is selected
with the TRIGGER SLOPE control, the slope cannot be
selected. Also you cannot use the PRESET position of the
STABILITY control in this mode.
Free-Running Sweep Operation
In the usual oscilloscope application, the sweep is trig­
gered or synchronized by the input waveform. However, in
some applications it may be more desirable to reverse the
process and initate the input waveform through use of a
periodically recurrent waveform from the oscilloscope. In
this type of application the sweep is caused to free-run and
an output from either the +GATE or SAWTOOTH con­
nectors is used to trigger or synchronize the input waveform
(see Figure 2-6).
OUTPUT OF THE EXTERNAL
EQUIPMENT IS
APPLIED TO
THE OSCILLOSCOPE INPUT.
FREE-RUNNING SWEEP]
GATE OR SAWTOOTH WAVEFORMS
ARE CONNECTED TO THE EXTERNAL
EQUIPMENT.
EQUIPMENT TO BE TRIGGERED
OR SYNCHRONIZED BY THE
OSCILLOSCOPE.
Fig. 2-6. Using the Gate or Sawtooth output waveforms to synchro­
nize or trigger external equipment.
The sweep can be made to free run with any setting of
the TRIGGERING mode switch by rotating the STABILITY
control fully clockwise. In all positions of the TRIGGERING
MODE switch except AUTO, the number of sweeps per
second is determined by the setting of the TIME/CM controls.
In the AUTO, position, the sweep repetition rate remains
at approximately 50 sweeps per second regardless of the
setting of the TIME/CM control.
In addition to providing the means for controlling an
applied waveform, a free-running sweep also provides a
a convenient reference trace on the oscilloscope screen
without requiring an input signal. This trace can then be
used to position the sweep or to establish a voltage refer­
ence line.
Delayed Sweep
With the Type 535A Oscilloscope the start of the hori­
zontal sweep can be delayed for a period of from 1 micro­
second to 10 seconds after application of the triggering
waveform. This is done through simultaneous use of the
Time Base A and Time Base B. In this application Time
Base B is used to provide the accurate time delay while
Time Base A presents a normal horizontal sweep at the
end of the delay period. The duration of the sweep delay
is controlled by the Time Base B TIME/CM OR DELAY TIME
switch
and the DELAY-TIME MULTIPLIER control.
The delayed sweep feature of the Type 535A Oscillo­
scope can be used in a number of special applications to
increase the versatility of the instrument. Such applications
include high magnification of a selected portion of an un­
delayed sweep, accurate time measure ments, and accurate
measurements of waveform jitter. Also, it is possible to
pick off and display any desired line of a television scan
or to check pulse-time modulation. In addition, the delayed
sweep feature is readily adaptable to a great number of
other applications.
The delayed sweep is selected when the HORIZONTAL
DISPLAY switch is in the ‘A' DEL'D BY 'B' position. The
amount of delay occuring from the application of the
triggering waveform until the sweep runs is indicated
directly by the settings of the TIME/CM OR DELAY TIME
switch and the DELAY TIME MULTIPLIER control. The set­
tings of the two controls are multiplied together to obtain
the actual delay time. For example, if the TIME/CM OR
DELAY TIME switch is set at 1 MILLISEC and the vernier
dial of the DELAY TIME MULTIPLIER control indicates 6.75,
the delay time is 6.75 milliseconds. When the Time Base A
STABILITY control is in the fully clockwise position, the
horizontal sweep starts immediately at the completion of
the delay period at a rate determined by the settings of
the Time Base A TIME/CM controls.
There are actually two modes of delayed sweep operation
available in the Type 535A Oscilloscope (see Figure 2-8).
In one mode the delayed sweep is started immediately after
the completion of the delay time. This is the mode de­
scribed previously and is obtained with the Time Base A
STABILITY control fully clockwise. This mode perimts you
to select continuously variable delay times and is the mode
of operation used to make accurate time and waveform
jitter measurements as well as most other measurements.
2-9