TB 9-6625-2021-24
8. Time Base Stability - Option 001 Only
a. Performance Check
(1) Connect time/frequency workstation 10 MHz output to frequency counter 10
MHz reference input connector and set frequency counter external reference on.
(2) Connect TI FREQ STD OUT 10 MHz output jack (rear panel) to frequency
counter Channel A input.
(3) Adjust frequency counter for a stable indication. Frequency counter should
indicate between 9.999998499 and 10.00000151 MHz (based on one year interval).
NOTE
To determine time base drift limits for TI with other intervals:
multiply aging rate per day by the interval (days).
(4) Connect time/frequency workstation 1 MHz output to frequency difference meter
REF INPUT.
(5) Connect TI 10 MHz OUTPUT (rear panel) to frequency difference meter
SIG INPUT.
NOTE
The time base is adjusted during each calibration in order to
correct for drift and improve reliability of the TI throughout the
interval. If TI is within the limits in step (3) above, then the
following FREQ ADJ adjustment will not be annotated as an
out-of-tolerance condition.
(6) Adjust FREQ ADJ (fig. 1) for a minimum indication on frequency difference
meter 1010 range. Record frequency difference meter indication.
(7) Allow at least 24 hours for TI time base oscillator to stabilize. Frequency
difference meter indication will be within 5 parts in 1010 of indication recorded in step (6)
above. Record frequency difference meter indication.
(8) Adjust autotransformer output to 105 V ac. Allow 1 minute for oscillator to
recorded in step (7) above.
(9) Adjust autotransformer output to 125 V ac. Allow 1 minute for oscillator to
recorded in step (7) above.
(10) Adjust autotransformer output to 115 V ac.
b. Adjustments. No further adjustments can be made.
