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 5334A/B Frequency Standard . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . HP 5061B Cesium Beam Standard (or any 10 MHz frequency standard with aging rate <f 1 X 10-r’ 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