HP 8568B manual Math SELECT/ENTER Cm 10 I-1 6 SELECT/E~&ER

12. Time Base Adjustment (SN 2848A to 3217A05567)

INT/EXT switch (rear panel) . . . . . . . . . . . . . . . . . . . . . EXT

7.On the Frequency Counter, select a 10 second gate time by pressing, (GATETIME_) 10 (GATE].

8.Offset the displayed frequency by -10.0 MHz by pressing,

MATH (SELECT/ENTER] Cm) 10 I-1 6 [SELECT/E~&ER]

(SELECT/ENTER). The Frequency Counter should now display the difference between the frequency of the INPUT A signal (A27 10 MHz Frequency Standard) and 10.0 MHz with a displayed resolution of 1 mHz (0.001 Hz).

9.Wait at least two gate periods for the Frequency Counter to settle, and record the frequency of the A27 10 MHz Frequency Standard as reading #l.

Reading 1: mHz

Note The A27A2 Quartz Crystal Oscillator has a typical adjustment range of 10 MHz *lO Hz. The oscillator frequency should be within this range after 48 hours of continuous operation.

10.Allow the spectrum analyzer to remain powered (not in STANDBY) and undisturbed for an additional 24 hours.

11.Repeat steps 3 through 7 and record the frequency of the A27 10 MHz Frequency Standard as reading #2.

Reading 2: mHz

12.If the difference between reading #2 and reading #l is greater than 1 mHz, the A27 10 MHz Frequency Standard has not achieved its specified aging rate; the spectrum analyzer should remain powered (not in STANDBY) and undisturbed for an additional 24-hour interval. Then, repeat steps 3 through 7, recording the frequency of the 10 MHz Frequency Standard at the end of each 24-hour interval, until the specified aging rate of 1 mHz/day (lxlOE9/day) is achieved.

Reading 3:	mHz
Reading 4:	mHz
Reading 5:	mHz
Reading 6:	mHz
Reading 7:	mHz

13.Position the spectrum analyzer on its right side as shown in Figure 3-54 and remove the bottom cover. Typically, the frequency of the A27 10 MHz Frequency Standard will shift slightly when the spectrum analyzer is reoriented. Record this shifted frequency of the A27 10 MHz Frequency Standard.

Reading 8: mHz

14.Subtract the shifted frequency reading in step 8 from the last recorded frequency in step 7. This gives the frequency correction factor needed to adjust the A27 10 MHz Frequency Standard.

Frequency Correction Factor: mHz

Adjustments 3-101