Model 8642A/B
Performance Tests
PERFORMANCE TESTS
for example:
if: Tl = 351s
T2 = 349s
T3 = 3h
then:
Aging Rate = ( ,\ ^ ) ("^ ££-) ("f^)
= 1.306 X 10"
11
7.
Record the aging rate.
Aging Rate 5 x 10-10/day
NOTE
// the absolute frequencies of the frequency standard
and the HP 8642s reference oscillator are extremely
close, the measurement time in steps 4 and 5 (T1 and
T2) can be reduced by measuring the time required
for a phase change of something less than 360
degrees. Change 1 cycle in the formula (e.g., 180
degrees
=
1/2 cycle, 90 degrees
=
1/4 cycle).
8. If the rate aging is not within the required tolerance, check the power
supplies before replacing A8A3. Be sure sufficient warm-up time has
been allowed (may require up to 10 days).
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