Fig. 4-32. Test equipment setup to check or adjust the phase lock circuit.
Type 491
INTENSITY
FOCUS AND ASTIGMATISM
SCALE ILLUM
POSITION (Horizontal and
Vertical)
TIME/DIV
VARIABLE
TRIGGER
SLOPE
LEVEL
SOURCE
DISPERSION RANGE
DISPERSION-COUPLED
RESOLUTION
IF ATTENUATOR dB
IF CENTER FREQ
VIDEO FILTER
VERTICAL DISPLAY
GAIN
POWER
Display of nominal
brightness
Adjusted for optimum
display definition
As desired
Adjusted for a horizon-
tally centered sweep on
the graticule baseline.
2 ms
CAL
+
Triggered
LINE
kHz/DIV
50 kHz/div
All switches in off position
Midrange (000)
OFF
LIN
Midrange
ON
MIXER PEAKING
SEARCH
FINE
RF CENTER FREQ
Centered
PHASE LOCK Controls
INT REF FREQ
ON
Test Oscilloscope
Time/Cm
.5 µs
Volts/Cm
.05
Input Coupling
AC
Triggering
Int.
Phase Lock Circuit
26. Adjust Avalanche Voltage
o
a. Equipment setup is given in Fig. 6-32.
b. Connect the Vertical Input of the test oscilloscope to
the 1 MHz MARKERS OUT connector ond turn the INT REF
FREQ control on.
c. Adjust the test oscilloscope for a triggered display.
See Fig. 6-33B.
d. Adjust the Avalanche Volts R1131. (Fig. 6-33), from a
fully ccw position, clockwise until the avalanche transistor is
6-29
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