610 Chapter12
RF Section
A13 Second Converter
A13 Second Converter
CAUTION The A13 assembly is extremely sensitive to Electrostatic Discharge
(ESD). For further information regarding electrostatic cautions, refer to
“Electrostatic Discharge” in Chapter 1 .
1. Connect the spectrum analyzer CAL OUTPUT to the INPUT 50Ω
connector.
2. Set the spectrum analyzer to the following settings:
Center frequency ..................................................... 300MHz
Span .................................................................................0Hz
Input attenuation .......................................................... 10dB
3. Disconnect W35 (coax 92) from A13J2.
4. Connect a test cable from A13J2 to the input of a second spectrum
analyzer.
5. Tune the second spectrum analyzer to 310.7 MHz. The signal
displayed on the second spectrum analyzer should be approximately
−38 dBm.
6. Remove the test cable from A13J2 and reconnect W35 to A13J2.
7. Disconnect W33 (coax 81) from A13J4 and connect W33 through a
test cable to the input of a second spectrum analyzer.
8. Tune the second spectrum analyzer to a center frequency of
600 MHz.
9. If a 600 MHz signal is not present, or its amplitude is less than
−5 dBm, the fault is probably on the A15 RF assembly.
10.Reconnect W33 to A13J4.
11.Connect the positive lead of a DVM to A14J19 pin 15 and the
negative lead to A14J19 pin 6.
If the DVM does not measure between +14.0 Vdc and +15.0 Vdc
perform the following:
a. Press
LINE to turn the spectrum analyzer being tested, off and
disconnect W13 from A14J12.
b. Press LINE to turn the spectrum analyzer on again and set the it
to the following settings:
Center frequency ................................................ 300MHz
Span ...................................................................... 10MHz
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