HP 8568B, Руководство по испытаниям и регулировке работы, Страница: 212 / 313

12. Time Base Adjustment (SN and Below, also and Above)
14.
15.
16.
Reading 11:
Subtract the shifted frequency reading in step 11 from the
last recorded frequency in step 10. This gives the frequency
correction factor needed to adjust the
10 MHz Frequency
Standard.
Frequency Correction Factor:
On the Frequency Counter, select a 1 second gate time
pressing,
1 The Frequency Counter should
now display the difference between the frequency of
the
INPUT
A signaland 10.0 MHz with a resolution of Hz (10
Remove the two adjustment cover screws from the 10 MHz
Quartz Crystal Oscillator. See Figure 3-53 for the location of the
10 MHz Frequency Standard.
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.
17.
18.
19.
20.
Use a nonconductive adjustment tool to adjust the FREQ
ADJ capacitor on the 10 MHz Quartz Crystal Oscillator for
a Frequency Counter indication of 0.00 Hz. See Figure 3-53 for
the location of the
10 MHz Quartz Crystal Oscillator.
R F S e c t i o n ( b o t t o m
Figure 3-53. Location of Adjustment
On the Frequency Counter, select a 10 second gate time by
pressing,
10 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
Wait at least 2 gate periods for the Frequency Counter to settle,
and then adjust the
FINE adjustment on the 10 MHz
Frequency Standard for a stable Frequency Counter indication of
(0.000 + Frequency Correction Factor) Hz.
Replace the RF Section bottom cover and reconnect
the
short
jumper cable between the FREQ REFERENCE INT and EXT
connectors,
3-98 Adjustments