HP 85662A, Troubleshooting And Repair Manual

Page: 343 / 594

Operation of the Step Gains and to A15.9 Attenuator can be determined from the
display by several easy tests.
The Step Gains are checked in the following way. Connect a 10 step attenuator between
CAL OUTPUT and the input to the analyzer. Set this attenuator to 90
press Instrument
Preset, and key in the following:
equal to the CAL OUTPUT frequency
0 Hz
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 Hz
( S W E E P ) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 s
-10
Press the sweep key and press the DATA STEP key to display each step. Figure 5
should be displayed. If one or more of the steps is missing, refer to Note 8 for the Step Gain
truth table to determine which stage is faulty. 0 V in the table indicates that a control line is
active.
R E F - 9 9 . 9 0
1 0
N O T E : C e n t e r F r e q u e n c y r e a d o u t w i l l b e 1 0 0 . 0 0 0 0 0 0 M H z f o r a n
R E F
- 9 9 . 3
I I I I
0
I
I I
I I I
I
C E N T E R 2 0 . 0 0 0 0 0 0 M H z
R E S B W 1
V B W 1 0 H z
S P A N 0 H z
2 0
AND
Figure 5. 10 Step Gain Test
If a component has been replaced, a simple calibration/diagnostic program exists. The
calibration routine is started by connecting a cable from CAL OUTPUT to the input of the
analyzer and then pressing
When this program has finished, press
TRIGGER h
w will list the calibration data. (Refer to Figure 6). Lines 19
5