Table of Contents
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1.
SECTION
14.
INSTALLATION AND MAINTENANCE
Remove the
21X battery base and unplug
the battery from the
21X.
Remove the
four
screws holding the aluminum
cover plate
and remove the cover
plate.
Lay
the 21X,
panel down, on a padded flat surface with
the circuit
cards up and exposed as shown
in Figure
14.10-1.
Plug
the battery back
into the
21X.
Turn
on
the 21X.
3.
Connect positive lead
of
the frequency
counter
to pin
3 of
the integrated circuit
shown at Location P10
on Figure 14.10-2.
Connect the ground lead to any one of the
capacitor leads
circled
in
the upper left
corner of
Figure 14.10-2. Adjust the
variable capacitor at location
516 for
a
period of
49999.0 microseconds (20 ppm
fast) or
50000.0 microseconds (exactly
on).
Lock the variable
capacitor into position
wi
a dab
of
fingernail polish.
2.
DAC
OUTPUT
TEST
POINT
(LEFT
SIDE)
DAC
OFFSET
POTENTIOMETER
VOLTAGE
REFERENCE
GAIN
POTENTIOMETER
14-8
FIGURE
14.10-1. Calibration Points for the
21X
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