D e t a i l e d

 

 

 

--- - \-,

 

..-_.

 

 

I f Adiust Sinnnture (Sl

M K R 1 854 <cc

hP

REF

-510

cjBm,-‘-ifTiN= dB

- 8 4 . 4 0 dBm

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

I

 

 

I

 

II ill

I

 

 

 

 

 

 

1 0

dB/

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

S A M P L E 1

 

IIilI

I

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

LC POLE LC POLE LC POLE

-

SETTINGS PAST HERE ARE FOR AUTOMATIC ADJUSTMENT OF THE 30kHz RESOLUTION BANDWIDTH

CENTER 1 0 . 7 0 0 0 0 0 M H z

 

SPAN

0 Hz

R E S B W 3 0 0 kHz

VBW 1 kHz

SWP 2 . 0 0

set

sp148e

Figure 9-8. Detailed IF Adjust Signature (5)

Common IF Signature Problems

Region A of Figure 9-4 is noisy:

Suspect the first LC pole.

Region B of Figure 9-4 is flat:

Suspect the third step-gain stage, the fine attenuator, or the fourth LC-pole output amplifier.

Region C of Figure 9-4 has no 15 dB step:

Suspect the reference 15 dB attenuator.

Region D of Figure 9-4 is flat:

Suspect the second step-gain stage.

Entire signature noisy:

If the signature resembles Figure 9-9, suspect a broken first 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:

If the signature resembles Figure 9-10, suspect the second crystal-pole output amplifier.

Amplitude of Region B of Figure 9-11 varies more than 12 dB:

Suspect the third step-gain stage output amplifier.

Region B of Figure 9-12 is kinked:

Suspect the fourth LC-pole output amplifier.

9-26 IF Section

Page 341
Image 341
Agilent Technologies 856290216 service manual Common if Signature Problems, CjBm,-‘-ifTiN= dB 0 dBm II ill M P L E IIilI