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INT/EXT switch (rear panel) . . . . . . . . . . . . . . . . . . . . . EXT
7. On the Frequency Counter, select a 10 second gate time by
pressing, (GATETIME_) 10 (GATE].
8. Offset the displayed frequency by -10.0 MHz by pressing,
MATH
(
SELECT
difference between the frequency of the INPUT A signal (A27
10 MHz Frequency Standard) and 10.0 MHz with a displayed
resolution of 1 mHz (0.001 Hz).
9. Wait at least two gate periods for the Frequency Counter to settle,
and record the frequency of the A27 10 MHz Frequency Standard
as reading #l.
Note
The A27A2 Quartz Crystal Oscillator has a typical adjustment range of
10 MHz *lO Hz. The oscillator frequency should be within this range
after 48 hours of continuous operation.
10. Allow the spectrum analyzer to remain powered (not in
STANDBY) and undisturbed for an additional 24 hours.
11. Repeat steps 3 through 7 and record the frequency of the A27 10
MHz Frequency Standard as reading #2.
12. If
the
than 1 mHz,
achieved its specified aging rate; the spectrum analyzer should
remain powered (not in STANDBY) and undisturbed for an
additional 24-hour interval. Then, repeat steps 3 through 7,
recording
end of each 24-hour interval, until the specified aging rate of 1
mHz/day (lxlOE9/day) is achieved.
13. Position the spectrum analyzer on its right side as shown
in Figure 3-54 and remove the bottom cover. Typically, the
frequency of the A27 10 MHz Frequency Standard will shift
slightly when the spectrum analyzer is reoriented. Record this
shifted frequency of the A27 10 MHz Frequency Standard.
14. Subtract the shifted frequency reading in step 8 from the last
recorded frequency in step 7. This gives the frequency correction
factor needed to adjust the A27 10 MHz Frequency Standard.
12. Time Base Adjustment (SN 2848A to 3217A05567)
(
/
] Cm)
SELECT
ENTER
The Frequency Counter should now display the
/
).
ENTER
difference between reading #2 and reading #l is greater
the
frequency of the 10 MHz Frequency Standard at the
the
Frequency Correction Factor:
10
6
Reading 1:
Reading 2:
Reading 3:
Reading 4:
Reading 5:
Reading 6:
Reading 7:
Reading 8:
Adjustments 3-101
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