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582 AMPL
Unable to adjust 100 kHz resolution bandwidth and resolution
bandwidths less than or equal to 10 kHz. Bad CALOSC Calibration
in Sweep Rate. Test the 100 kHz resolution bandwidth filter 3 dB
bandwidth as follows:
1. Connect the CAL OUTPUT signal
(A4J8)
to the INPUT
500.
2. Press
(W)
and set the controls as follows:
Center frequency
..................................
300 MHz
Span
...........................................
..5OOkH
z
Resolution bandwidth
..............................
100
kHz
Log dB/div
..........................................
1
dB
Reference level . . adjust to place signal peak at top of the screen
3. Press (PEAK SEARCH) and
MAEEEE
DELTA and turn the knob
clockwise to position the marker until the delta MKR reads -3 dB
fO.l dB.
4. Press
MAEEEE
DELTA and move the marker to the other side of the
peak until the delta MKR reads 0 dB fO.l dB.
5. If the delta MKR frequency is between 90 kHz and 110 kHz, the
100 kHz resolution bandwidth is working properly. If the frequency
is outside these limits, read the following information on the A4 Cal
Oscillator sweep generator.
If the 100 kHz resolution bandwidth works properly, the cal oscillator
sweep generator is failing to sweep its oscillator frequency at the
correct rate. The error is detected in sweeping on the skirts of the
100 kHz resolution bandwidth.
A properly operating sweep generator generates a series of
negative-going parabolas. These parabolas generate the sweeps used to
adjust resolution bandwidths of 10 kHz and below. Check the sweep
generator with the following steps. Refer also to “300 Hz to 3 kHz
resolution bandwidth Out of Specification” in the A4 Cal Oscillator
troubleshooting text in Chapter 9, “IF Section.”
1. Remove the shields.
2. Connect an oscilloscope probe to A4U804C pin 8.
3. On the spectrum analyzer, press
ICAL)
and FULL IF
Al3J.
4.
Approximately 8 seconds after starting the FULL IF
ADJ
, check
for negative-going parabolas (similar to half-sine waves) 5 ms wide
and approximately -4 V at their peak. Refer to Chapter 9, “IF
Section,” for more information on the A4 Log Amp/Cal Oscillator
Assembly.
7-36 General Troubleshooting