Flatness Adjustment - HP 3585A Service Manual

Model 3585A
5·36. Flatness Adjustment
a. Move test jumper A 1 5W 1 to the "TEST" position.
b. Set the 3585A controls for:
c. Using the Continuous Entry control, adjust the REF LVL so that the trace is centered
on the CRT.
d. The 3585A is now in its 0.2dB/DIV mode. This allows very fine adjustment of the in­
struments flatness.
e. Adjust the input flatness with the following components in the order shown.
The input flatness of the instrument should resemble Figure 5-39 when completely adjusted.
The effect of each adjustment is shown in Figure 5-40 (foldout). Continue adjustment of the
instrument flatness until the peak to peak variation of the trace is less than 0.2dB
division).
f. Move test jumper A 1 5W 1 to the "NORM" position.
REF -25. 0 dBm
10 dB/O I V RANGE -25. 0 dBm
- - - - - - - - - - - - - - - - - - - -
CENT E R 20 000 000. 0 H z
RBW 30 KHz VBW 30 KHz
Figure 5·38. Normal Display For Test Mode 05
RECALL 605
INSTRUMENT PRESET
CENTER FREQUENCY . . . . . . . . . . . . . . . . . . 20. 1 MHz
dB/DIV . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2dB
RANGE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . - 25dBm
AUTO RANGE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . off
A 1 R 1 3 1 , C83, L 1 8, C86, L 1 9, C89, L21 , C92
MARKER 20 000 (JOO. O Hz
-37. 1 dBm
t
,
,
-
- - - - - - - - - - - - . - - - - - - -
SPAN 4 0 000 000. 0 Hz
ST . 2 SEC
Adjustments
(l
5-5 9