Tektronix 1S1 Instruction Manual page 15

Operating Instructions – Type 1S1
22. With the DC OFFSET control, position the display to
the center of the crt screen.
23. Turn the SAMPLES/CM control through its range of
rotation and note the change in dot density from about 5
samples/cm at the MIN (clockwise) position to many thou-
sands of samples/cm at the counterclockwise end of rotation.
CAUTION
Always decrease the crt beam intensity whenever
a stationary spot or slow-moving display is on
the screen. Excessively high intensity can damage
the crt screen.
24. Switch the SAMPLES/CM control to the SWEEP OFF
position. The displayed dot remains on the crt screen at the
position of the trace at the time the control was switched.
(The dot may move slowly across the screen.)
25. Switch the SAMPLES/CM switch out of SWEEP OFF
position and adjust it for as dense a trace as possible with
minimum display flicker.
26. With the TIME POSITION control, move the displayed
pulse to the left edge of the screen so that the trace starts
on the pulse rise (see Fig. 2-3).
27. Pull out on the MAGNIFIER knob and turn the TIME/
CM switch clockwise one position. Note that the display
time- magnification takes place at the left edge of the screen.
Also notice that there is no change in horizontal dot density.
Since the equivalent time per cm is decreased, however, the
dot density is increased in equivalent time, producing a
more continuous trace on the pulse rise.
28. Turn the TIME/CM switch to the .5 nSEC, .2 nSEC
and .1 nSEC positions. (It is not necessary to pull on the
MAGNIFIER knob except when intially disengaging it from
the TIME POSITION RANGE switch.) Observe the display
expansion.
29. Return the TIME/CM switch to 2 nSEC. The MAGNI-
FIER knob will automatically engage with the TIME POSI-
TION RANGE switch.
30. Set the DISPLAY MODE switch to SINGLE SWEEP.
31. Press the START button. A single triggered sweep
of the display is presented each time the START button is
pressed.
32. Set the DISPLAY MODE switch to MAN position.
33. Turn the red MANUAL SCAN (EXT HORIZ ATTEN)
knob slowly counterclockwise and note that the same pulse
display is traced out on the crt. The TIME/CM switch still
determines the equivalent-time sweep rate of the display and
the TIME POSITION control still determines the display posi-
tion.
34. Connect a patch cord from the oscilloscope Sawtooth
Output jack to the Type 1S1 EXT HORIZ INPUT jack.
35. Set the oscilloscope triggering controls for a free-
running sweep to generate a sawtooth output.
36. Set the oscilloscope Time/Cm switch to 10mSec.
37. Set the Type 1S1 DISPLAY MODE switch to the EXT
HORIZ position.
38. Adjust the Type 1S1 EXT HORIZ ATTEN control for a
horizontal deflection of about 10cm. Notice that in this
2-6
mode, similar to manual scan, the external horizontal in-
put voltage determines the crt spot position, but the Type 1S1
TIME/CM switch still determines the equivalent-time sweep
rate of the display. Since the external voltage merely scans
the display, the sawtooth voltage scans on both the ramp and
retrace portions of the sawtooth waveform.
39. Turn the SAMPLES/CM control. Notice that the dot
density of the display is not controlled by the SAMPLES/CM
control when the display is externally scanned, but is instead
controlled by the rate of scanning and by the trigger repe-
tition rate. (The same is true when the display is manually
scanned.)
40. Return the DISPLAY MODE switch to NORMAL.
41. Adjust the SAMPLES/CM control for a dense display
with minimum flicker.
42. Set the TIME POSITION control to position the pulse
display to the right of the vertical centerline.
43. Set the TRIGGER SOURCE switch to INT -.
44. Readjust the TRIGGER SENSITIVITY control if
necessary for a triggered display. Notice that the displayed
pulse has shifted to the left due to the fact that the triggering
occurs at essentially the same time, but now is on the
negative-going slope. (There is also a slight additional shift of 1
or 2 nsec due to the inverting transformer.)
45. Return the TRIGGER SOURCE switch to INT +.
46. Disconnect the pulse input signal.
47. Connect a 10-Mc sine wave of about 1 volt ampli-
tude (e.g. from a Tektronix Type 180A through 5X atten-
uation) to the SIGNAL IN connector.
48. Set the TIME/CM switch to 50nSEC.
49. Trigger the display with the TRIGGER SENSITIVITY
control. The control should be set to the most stable trigger-
ing point.
50. Slowly turn the RECOVERY TIME control through its
range of rotation. Note that several positions of the control
provide stable triggering of the display.
51. Switch the RECOVERY TIME control to SYNC posi-
tion.
52. Adjust the TRIGGER SENSITIVITY control for a stable
display. This synchronized mode of operation is normally
used for input signals from 20 Mc to 1 Gc.
53. Switch the RECOVERY TIME control out of SYNC posi-
tion and set it to midrange. Readjust the TRIGGER SEN-
SITIVITY control if necessary.
54. Turn the TIME POSITION and FINE controls fully
clockwise.
55. With the TIME/CM MAGNIFIER knob locked to the
TIME POSITION RANGE switch, set the TIME/CM switch to
20 nSEC. This sets the TIME POSITION RANGE switch to
500 nS. Each cycle of the 10-Mc waveform represents 100
nsec of time.
56. Observe the display while turning the TIME POSITION
control fully counterclockwise. Notice that approximately
4½ cycles of the waveform, representing approximately
450 nsec, pass the left edge of the crt screen.