HP 8568B mHz, mHz, mHz, mHz, mHz, mHz, mHz, mHz, mHz, mHz, MATH, GATE], Allow, Reading 1:, Reading 2:, Reading 3:, Reading 4:, Reading 5:, Reading 6:, Reading 7:

12. Time Base Adjustment (SN 2840A and Below, also 3217A05568 and Above)

6. Set the Frequency Counter controls as follows:

INPUT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A ATTENUATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .x10 DC Coupled . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . OFF 1 Mdl input impedance . . . . . . . . . . . . . . . . . . . . . . . . . . OFF AUTOTRIG . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ON 100 kHz FILTER . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . OFF INT/EXT switch (rear panel) . . . . . . . . . . . . . . . . . . . . . EXT

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

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

MATH CSELECT/ENTER) C-1 10 [CHS/EEX) 6 [SELECT/ENTER)

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

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 (lxlOES/day) is achieved.

Reading 3:	mHz
Reading 4:	mHz
Reading 5:	mHz
Reading 6:	mHz
Reading 7:	mHz
Reading 8:	mHz
Reading 9:	mHz
Reading 10:	mHz

13.Position the spectrum analyzer on its right side as shown in Figure 3-52 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.

Adjustments 3-97