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12. Time Base Adjustment (SN 2848A to 3217A05567)
15. On the Frequency Counter, select a 1 second gate time by
pressing,
t-1
1
@Y%YiK].
The Frequency Counter should
now display the difference between the frequency of the INPUT
A signal and 10.0 MHz with a resolution of 0.01 Hz (10
mHz).
Note
Do not use a metal adjustment tool to tune an oven-controlled
crystal oscillator (OCXO). The metal will conduct heat away from the
oscillator circuit, shifting the operating conditions.
16.
17.
18.
19.
Use a nonconductive adjustment tool to adjust the 18-turn FREQ
ADJ capacitor on the
A27A2
10 MHz Quartz Crystal Oscillator for
a Frequency Counter indication of 0.00 Hz. See Figure 3-55 for
the location of the
A27A2
10 MHz Quartz Crystal Oscillator.
RF Section (bottom
view)
Figure 3-55. Location of A27A2 Adjustment
On the Frequency Counter, select a 10 second gate time by
pressing,
[GATETIME)
10
C-1.
The Frequency Counter
should now display the difference between the frequency of the
INPUT A signal and 10.0 MHz with a resolution of 0.001 Hz (1
mHz).
Wait at least 2 gate periods for the Frequency Counter to settle,
and then adjust the FREQ ADJ capacitor on the
A27A2
10
MHz Quartz Crystal Oscillator for a stable Frequency Counter
indication of (0.000 + Frequency Correction Factor)
fO.O1O
Hz.
Replace the RF Section bottom cover and reconnect the short
jumper cable between the FREQ REFERENCE INT and EXT
connectors.
3-102 Adjustments