Tektronix 1S1 Instruction Manual page 90

Amplitude Calibrator
Display
Millivolts/Cm
Input Atten
Millivolts/Cm Variable
Vc Range
Comparison Voltage
Input Coupling (Chan
nel A)-
Input Coupling (Channel
B)
Pretrigger Pulse Generator
Repetition Rate
Range
Output Polarity
18. Adjust Loop Gain
(Steps b through q establish a synchronous 2-trace pulse
display for adjusting the controls that affect sampling loop
1
gain).
a. Test equipment setup is shown in Fig. 5-29.
b. Connect the tip of the test probe to the Type 1S1
HORIZ OUTPUT jack.
c. Trigger the test oscilloscope display.
d . Measure and record the approximate time interval be-
tween alternate pulses on the waveform at the HORIZ OUT-
PUT jack (see Fig. 5-30A).
e. Set the test oscilloscope Input Atten switch to 100.
f. Touch the tip of the test probe to the pulse generator
Pretrigger Output connector.
g. Trigger the test oscilloscope display.
h. Adjust the pulse generator Repetition Rate control to
produce a time interval between pulses equal to the ap-
proximate interval between alternate cycles of the wave-
form at the Type 1S1 HORIZ OUTPUT jack (see Fig. 5-30B).
You may wish to record this setting of the Repetition Rate
control for future reference, such as in step 31. Record the
knob position as the number of degrees from center position
(e.g. 95° clockwise from center).
i. Remove the test probe from the Pretrigger Output.
i. Connect the Pulse Output signal of the pretrigger pulse
generator through a coax cable, the variable attenuator
and a 5X attenuator to the SIGNAL IN connector of the Type
1S1. (The Type 111 Pretrigger Pulse Generator should have
a 9-nsec charge line installed, for an Output Pulse duration
of 20 nsec.)
1
A modified Type 111 Pretrigger
is available to provide an
these adjustments. See your Tektronix Field Engineer for details.
Off
A-Vc
5
1
Calib (at detent)
0
4.000
Ac
Gnd
Centered
10Kc
+
Pulse Generator (067-0517-00)
automatic 2-trace pulse display
k. Set the variable attenuator control to midrange.
l. Set the Type 1S1 DISPLAY MODE switch to NORMAL.
m. Trigger the display with the Type 1S1 TRIGGER SEN-
SITIVITY control. (it may be necessary to increase the dis-
play intensity to observe the triggered trace.) ,
n. Adjust the Type 1S1 SAMPLES/CM control for a normal
continuous display.
Fig. 5-30. Typical test oscilloscope displays for adjusting
pretrigger pulse generator repetition rate to produce 2 trace
sampling display. (A) Waveform at Type 1S1 HORIZ OUTPUT
(B) pretrigger pulse of pretrigger pulse generator.
o. Position the pulse to the center of the screen with the
TIME POSITION and DC OFFSET controls.
p. Adjust the variable attenuator for approximately 5 cm
of vertical deflection on the indicator oscilloscope crt (see
Fig. 5-31A).
q. Set the Type 1S1 SMOOTHING control fully counter-
clockwise.
r. Turn the TRIGGER SENSITIVITY control fully clockwise.
s. Adjust the RECOVERY TIME control to obtain a 2-
trace display as shown in Fig. 5-31B). Stability of the display
may be improved by slight readjustment of the TRIGGER
SENSITIVITY and RECOVERY TIME controls.
t. Turn the SMOOTHING control fully clockwise.
for
Calibration – Type 1S1
5-27