HP 8560A, Service Manual

Page: 102 / 450

19. 10 MHz Reference Adjustment (Option 003)
Assembly Adjusted
A21 OCXO Assembly
Note Replacement oscillators are factory adjusted after a complete warmup and
after the specified aging rate has been achieved. Thus, readjustment should
typically not be necessary after oscillator replacement and is generally not
recommended.
Related Performance Test
10 MHz Reference Accuracy (Option 003)
Description
The frequency of the internal 10 MHz frequency reference is compared to a known frequency
standard and adjusted for minimum frequency error. This procedure does not adjust the
short-term stability or long-term stability of the A21 10 MHz Ovenized Crystal Oscillator
(OCXO). Stability is determined by the characteristics of the particular oscillator and the
environmental and warmup conditions to which it has been recently exposed. The spectrum
analyzer must be on continuously for at least 24 hours immediately prior to oscillator
adjustment to allow both the temperature and frequency of the oscillator to stabilize.
Equipment
Frequency Counter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . HP
Frequency Standard . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . HP 5061B Cesium Beam
Standard (or any 10 MHz
frequency standard with
aging rate 1 X per day)
Cable
BNC, 122 cm (2
required) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
HP 10503A
Procedure
Note The spectrum analyzer must be on continuously for at least 24 hours
immediately prior to oscillator adjustment to allow both the temperature and
frequency of the oscillator to stabilize. Failure to allow sufficient stabilization
time could result in oscillator misadjustment.
2-68 Adjustment Procedures