If Signature; Noisy Signature; Common If Signature Problems - HP 8560A Service Manual

Common IF Signature Problems

Region A of Figure
8-4
n
Region B of Figure
8-4
n
fourth LC-pole output amplifier.
Region D of Figure
8-4
n
Entire signature noisy:
n
step-gain stage or a break in the signal path in the input switch, first crystal pole, or second
crystal pole.
Correct shape but noisy:
n
crystal-pole output amplifier.
Amplitude of Region B of Figure
n
stage output amplifier.
Region of Figure
8-12
B
n
R E F 1 0 . 0
5
S A M P L E
1 0 7 0 0
C E N T E R
R E S B W 3 0 0
8-28 IF Section
is noisy:
Suspect the first LC pole.
is flat:
Suspect the third step-gain stage, the fine attenuator, or the
15 Suspect the reference 15 dB attenuator.
is flat:
Suspect the second step-gain stage.
If the signature resembles Figure 8-9, suspect a broken first
If the signature resembles Figure 8-10, suspect the second
varies more than
8-11
is kinked:
Suspect the fourth LC-pole output amplifier.
0
I I
V B W 3 0 0
Figure 8-9. Noisy Signature
12 Suspect the third step-gain
I
S P A N 0 H z
S W P 5 0 0
S K 1 7 8