Tektronix 535A, Instruction Manual

Page: 12 / 156

Operating Instructions —Type
535A
PROBE TIP CONNFCTED TO SIGNAL SOURCE
EQUIPMENT BEING CHECKED
Fig. 2-1. Proper conneelion
of
a probe to the input signal source.
Before using a probe you must check (and adjust if neces­
sary)
the compensation of the probe to prevent distortion of
the applied waveform. The probe is compensated by adjust­
ing the control located in the body of the probe. To adjust
the probe compensation control, place the HORIZONTAL
DISPLAY switch at A, the TIME BASE A TRIGGERING MODE
switch at AUTO, and the TIME BASE A TRIGGER SLOPE
switch at +INT. Turn up the intensity until the trace is
visible and connect the probe tip to the CAL OUT connector.
Set the AMPLITUDE CALIBRATOR switch for 2 centimeters
of displayed signal. Set the TIME BASE A TIME/CM switch
to display approximately 3 or 4 cycles of the Calibrator
waveform and adjust the probe compensation control to
obtain flat tops on the displayed Calibrator square-waves
(see Figure 2-2).
Horizontal Sweep
The usual oscilloscope display is a graphical presentation
of instantaneous voltage versus time. Voltage information
is presented by vertical deflection of the trace and time
information is presented by horizontal deflection. To obtain
a useful display, it is necessary for the spot formed by the
electron beam to be deflected horizontally at a known
rate so that any horizontal distance on the screen repre­
sents a definite known period of time. The trace formed
by the deflection of the spot across the screen is known as
the horizontal sweep. Since the horizontal deflection of
the spot bears a definite relationship to time and provides
the means for making time measurements from the screen,
the horizontal sweep is also known as the time base.
The Type 535A Oscilloscope features two independent
time-base units: Time Base A and Time Base B. Either of the
two time bases may be displayed on the oscilloscope screen
at any time. Controls affecting Time Base A and Time Base
B operation are in the correspondingly labeled blocks
on the oscilloscope front panel. The HORIZONTAL
DISPLAY switch determines which time base is used
and the type of display to be presented. Time Base
A is selected when the HORIZONTAL DISPLAY switch is in
position A and Time Base B is selected when the switch is
in position B.
The rate at which the spot is deflected across the screen
is accurately controlled by the setting of the appropriate
TIME/CM controls. The settings of the TIME/CM controls
2-3