TB 9-6625-2339-24
i. Press TI key.
Wait for frequency counter to stabilize and record reading as "Counter Reading 2".
j.
k. Press TI key twice.
Wait for frequency counter to stabilize and record reading as "Counter Reading 3".
l.
m. Press Preset key (press the Factory Preset soft key if it is displayed).
n. Subtract "Counter Reading 1" from "Counter Reading 2" and record the difference as
"Positive Frequency Change".
o. Subtract "Counter Reading 3" from "Counter Reading 1" and record the difference as
"Negative Frequency Change".
p. Select the largest absolute value between "Positive Frequency Change" and
"Negative Frequency Change" and record value as "Maximum Frequency Change".
q. Calculate settability by dividing "Maximum Frequency Change" value by 2.
The
calculated value will be ≤5 Hz.
NOTE
The analyzer must sit with the power off for at least 60
minutes before performing the following test. This adequately
simulates a cold start.
r. Set up frequency counter to measure frequency to 0.001 Hz resolution.
s. Wait 5 minutes then record frequency counter reading to 0.001 Hz resolution as
counter reading 1.
t. Wait 10 more minutes then record frequency counter reading to 0.001 Hz resolution
as counter reading 2.
u. Wait 45 more minutes the record frequency counter reading to 0.001 Hz resolution
as counter reading 3.
v. Calculate the 5 minute warm-up error (in ppm) by subtracting counter reading 3
from counter reading 1 and dividing the result by 10. The calculated value will be
0 0.1 ppm.
w. Calculate the 15 minute warm-up error (in ppm) by subtracting counter reading 3
from counter reading 2 and dividing the result by 10. The calculated value will be
0 0.01 ppm.
x. If time base is out of tolerance perform (1) through (9) below:
(1) Press System key.
(2) Press [More 1 of 3].
(3) Press [More 2 of 3].
(4) Press [Service].
(5) Press 2, 0, 1, 0, Enter keys.
(6) Press [Service].
(7) Press [Timebase].
(8) Press [Course] or [Fine] as needed and adjust rotary knob for a frequency
counter indication as close to 10.00000000 MHz as possible.
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