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MAINTENANCE
WJ-8718-19/FE HF RECEIVER
•
Test Point
E3
U2-4
U3-1
El
4.3.4.9
Energize the receiver.
Set the receiver front panel
controls as follows:
a.
Gain Mode
b.
RF Gain
c .
Freq.
Manual
Maximum Clockwise
42.0000 MHz
6.
The RF Voltmeter should display a level > 0 dBm.
7.
IF the signal in step 6 is incorrect, check the Test
Points given in Table 4-9 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 6-9, 2nd
Converter Schematic Diagram should be referred to if
additional signal tracing/fault isolation is necessary.
8.
When the 2nd Converter has been repaired and is
operating satisfactorily, deenergize the receiver and
disconnect test equipment, if no further tests are to
be performed.
Table 4-9.
2nd Converter Fault Isolation Chart
Normal Signal
-6 dBm
+ 15 dBm
-15 dBm
0 dBm
Key Components
1st Converter
U2
U3
Ul
Comments
2nd LO Signal
2nd IF Signal
1st Converter, FE-A1A2A3, (270901) Testing and Troubleshooting
1st Converter 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 4-10 for fault isolation.
1.
Deenergize the receiver.
2.
Connect the signal generator to FE-A1A2-J2.
Connect
the RF voltmeter to FE-A1A2-J3.
3.
Set the generator to -20 dBm at 42.0000 MHz.
4-24
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