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30 kHz Resolution Bandwidth Problems
Shape factor too high:
Shape factor is the ratio of the 60 dB bandwidth to the 3 dB
bandwidth. Shape factor should be less than 15:l. If one of the LC poles malfunctions, the
shape factor may be the only indication of the failure. Isolate the non-functioning pole with
the IF signature. Region E of Figure 8-8 illustrates the four LC- pole adjustments. Take
several signatures to examine the LC-pole adjustments. If one of the four sections of Region E
is consistently longer than the others, the corresponding LC pole is faulty.
IF gain compression: FET
Measuring less than 0 volts on the FET source indicates a bad FET.
Bandwidth too wide:
Check for contamination on the printed-circuit board. Clean the board
as required.
3 kHz and 10 kHz Resolution Bandwidth Problems
Asymmetric Filter Response:
1. Press (PRESET).
2. Set the spectrum analyzer controls as follows:
RES BW . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3kHz
SPAN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100 kHz
FREQUENCY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100kHz
3. On the spectrum analyzer, connect the 300 MHz CAL OUTPUT to the INPUT 500.
4. A trace similar to Figure 8-15 indicates a failed crystal-symmetry circuit.
Narrow 10 kHz resolution bandwidth:
the board as required.
IF Gain Compression in 10 kHz resolution bandwidth: FET
and Q503 can deteriorate with age. Measuring less than 0 volts on the FET source indicates a
bad FET.
8-32 IF Section
transistors Q301, Q303, Q700, and Q701 can deteriorate with age.
Check the crystal symmetry control with the following steps.
Check for printed-circuit board contamination. Clean
transistors Q202, Q203, Q501,
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