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Performance Test Failures
Failures in IF-Section-related performance tests may be investigated using the following
information.
IF
Gain
Uncertainty
Performance
lest
Failure of this performance test indicates a possible problem with the spectrum analyzer IF
gain circuits. Assuming no major IF problems causing IF adjustment errors, IF gain problems
in the first 50 dB of IF gain (REF
LVLs
of 0
dBm
to -50
dBm
with 10 dB
ATTEN)
are a
result of faults on the A5 IF Assembly. IF gain problems in the next 60 dB of IF gain (REF
LVLs
of -60
dBm
to -110
dBm,
10 dB
ATTEN)
result from log amplifier faults on the A4
assembly.
A signal level of -5
dBm
is required at input
(A5J3)
for displaying a signal at top screen with
10 dB input attenuation and a 0
dBm
reference level.
Isolate IF gain problems on the log amplifier assembly (A4) with the following steps:
I. On the spectrum analyzer, press
[PRESET],
[SPAN),
ZlXRO
SPBN
,
k-1,
1
(GHz),
(-1,
-50
dBm.
2.
Press
ICAL)
and
IF AD3 OFF.
3. Disconnect cable W27 (coax 3) from A5J5 and connect cable W27 to the output of a signal
generator.
4. Set the signal generator controls as follows:
Amplitude . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . i-10
dBm
Frequency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
10.7MHz
5. Simultaneously decrease the signal generator output and the spectrum analyzer REF
LVL in 10 dB steps. The signal displayed by the spectrum analyzer should remain at the
reference level for each step. If the signal deviates from the reference level, troubleshoot the
video offset circuitry on the A4 assembly.
6. Repeat steps 1 through 5 with the spectrum analyzer set to linear.
Scale
Fidelity
Performance
lest
Failure of this performance test indicates a possible problem with the A4 assembly.
w
If the Linear, 5
dB/div,
or 10
dB/d
iv scales are out of specification, the fault is most likely
on the log amplifier assembly (P/O A4).
n If only the 1
dB/d
iv or 2 dB/div scales are out of specification, the fault is most likely on
the A3 interface assembly.
9-12 IF Section