Watkins-Johnson Company WJ-8718-19/FE Instruction Manual page 174

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4.3.4.6 Preselector, FE-A1A1A3, (794274) Testing and Troubleshooting
Preselector Testing and Troubleshooting includes a checkout procedure
and fault isolation information. A Signal Generator and an RF Voltmeter (see
Table 4-1) are required to perform the tests outlined below.
Perform the following procedure in the sequence given. If any specified
result is not obtained, refer to Table 4-7 for fault isolation.
1. Deenergize the receiver.
2. Connect the signal generator to the rear panel RF input
jack. Set the generator for -20 dBm output at 42.0000
MHz.
3. Energize the receiver. Set the receiver front panel
controls as follows:
a.
Gain Mode-
Manual
b.
RF Gain -
Maximum Clockwise
c .
Freq.
42.0000 MHz
4. Obtain access to module FE-A1A1A3. Connect the RF
Voltmeter to terminal El using a high impedance probe.
7. The RF Voltmeter should display a level > -18 dBm.
8. Change the receiver and the generator to 76.5 MHz.
The RF Voltmeter should display a level > -18 dBm.
9. IF the signal in steps 7 and 8 is incorrect, check the
Test Points given in Table 4-6 with an RF Voltmeter
and high impedance probe. When a faulty signal is
encountered, replace the key components indicated and
repeat the Checkout Procedure. Figure 6-6, Preselector
Schematic Diagram should be referred to if additional
signal tracing/fault isolation is necessary.
9. When the Preselector has been repaired and is operating
satisfactorily, deenergize the receiver and disconnect
test equipment, if no further tests are to be performed.
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