INTENSITY
FOCUS and ASTIGMATISM
INTENSIFIER
SCALE ILLUM
POSITION (Horizontal
and Vertical)
Fig. 6-11. Equipment setup for adjusting and checking triggering,
Type 491
TIME/DIV
VARIABLE
TRIGGER
SLOPE
LEVEL
SOURCE
DISPERSION RANGE
DISPERSION-COUPLED
RESOLUTION
IF ATTENUATOR dB
IF CENTER FREQ
VIDEO FILTER
VERTICAL DISPLAY
GAIN
Display of nominal
brightness
Adjusted for optimum
display definition
OFF
As desired
Adjusted for a
horizontally centered
sweep on the graticule
baseline
2 ms
CAL
+
FREE RUN
INT
MHz/DIV
5 MHz/DIV
All switches in off position
Midrange (000)
OFF
LIN
Midrange
POWER
ON
MIXER PEAKING SEARCH
FINE RF CENTER FREQ
Centered
PHASE LOCK Controls
INT REF FREQ ON
Test Oscilloscope
Time/Cm 1 ms
Volts/Cm
.2
Input Coupling DC
Trigger
Adjust for free running
sweep
9. Adjust Trigger Level Centering
o
a. Equipment setup is shown in Fig. 6-11.
b. Apply the output signal of the Audio Signal Generator
to pin H of the Vertical Amplifier circuit board. Set the Audio
Signal Generator frequency to 20 kHz.
c. Adjust the Trigger LEVEL control for a voltmeter read-
ing of 0 volts between pin C (see Fig. 6-12) of the Hori-
zontal Display board and chassis ground.
d. Adjust the output of the Audio Generator for 0.2 divi-
sion (1 minor division) display amplitude on the Type 491.
e. Adjust the Trig Lev Center R724, for stable sweep
triggering on both + and - SLOPE switch positions.
6-14
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