4. Set the signal generator controls as follows:
Amplitude
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
+lO
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 4 with the spectrum analyzer set to linear.
Scale Fidelity Performance Test
Failure of this performance test indicates a possible problem with the A4 assembly.
n If the Linear, 5
dB/DIV,
or 10 dB/DIV scales are out of specification, the fault is most
likely on the A4 Log Amplifier assembly.
n If only the 1 dB/DIV or 2 dB/DIV scales are out of specification, the fault is most likely on
the A3 Interface assembly.
Resolution Bandwidths Performance Tests
Most resolution bandwidth problems are a result of A5 IF assembly failures. The resolution
bandwidths are adjusted in the following sequence using 300 kHz as the reference: 1 MHz,
100 kHz, 30 kHz, 10 kHz, 3 kHz, 1 kHz, 300 Hz, 100 Hz, 30 Hz, 10 Hz, and 2 MHz.
If the IF adjustment routine encountered an error, the previously adjusted resolution
bandwidths should be working properly and default DAC values are used for the remaining
resolution bandwidth settings.
If the IF
bandpass
adjustments and the automatic IF adjustments fail to bring the resolution
bandwidths within specification, troubleshoot the A5 IF assembly.
IF Section 8-13
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