HP 8568B, Performance Tests And Adjustments Manual, Page: 216 / 313

12. Time Base Adjustment (SN to
15. On the Frequency Counter, select a 1 second gate time by
pressing, 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 0.01 Hz (10
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 FREQ
ADJ capacitor on the 10 MHz Quartz Crystal Oscillator for
a Frequency Counter indication of 0.00 Hz. See Figure 3-55 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 3-55. 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 FREQ ADJ capacitor on the
10
MHz Quartz Crystal Oscillator 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.
3-102 Adjustments