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WJ-8718-19/FE HF RECEIVER
MAINTENANCE
Table 4-24.
Output Loop Fault Isolation Chart.
Test Point
Normal Signal
Key Components
Comments
Q6-B
2 Vpp Q 32 MHz
Q6, CR4
VCO Circuit
Q3-1
5 Vpp @ 32 MHz
Q3
U6-3
5 Vpp @ 200 kHz
U4, U5, Q2
U6-8
+3 Vdc
U6
Phase Detector
4.3.4.22
3rd LO Synthesizer, p/o A5A1, (p/o 791630) Testing and Troubleshooting
3rd LO Synthesizer Testing and Troubleshooting includes a checkout
procedure and fault isolation information. AFrequency Counter, wideband Oscilloscope,
and RF Voltmeter (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 4-25 for fault isolation.
1.
Deenergize the receiver.
2.
Disconnect connector W6P10 from J7.
3.
Connect the Frequency Counter to W6P10.
4.
Energize the receiver.
The Frequency Counter should
indicate 11.155 MHz.
5.
Disconnect the Frequency Counter and connect the RF
Volt meter and 50 ohm probe to W6P10.
The Voltmeter
should indicate -6 dBm +/- 2 dBm.
8.
If the signal in step 5 is incorrect, check the test
points given in Table 4-25 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 6-25, 1st & 3rd
LO Synthesizer Schematic Diagram should be referred to
if additional signal tracing/fault isolation is necessary.
9.
When the 3rd LO has been repaired and is operating
satisfactorily, deenergize the receiver and disconnect
test equipment, if no further tests are to be performed.
4-43
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