Operator`s manual

SECTION 14. INSTALLATION AND MAINTENANCE
14-8
1. 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.
2. 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 S16 for a
period of 49999.0 microseconds (20 ppm
fast) or 50000.0 microseconds (exactly on).
3. Lock the variable capacitor into position with
a dab of fingernail polish.
FIGURE 14.10-1. Calibration Points for the 21X