1St Converter Fault Isolation Chart - Watkins-Johnson Company WJ-8718-19/FE Instruction Manual

l> I X W X *J I i J—'
iViAlW 1 tIN ANUL
Energize the receiver,
controls as follows:
Set the receiver front panel
a.
b.
c .
Gain Mode-
RF Gain -
Freq.
Manual
Maximum Clockwise
42.0000 MHz
6. The RF Voltmeter should display a level of 0 dBm.
7. IF the signal in step 6 is incorrect, check the Test
Points given in Table 4-10 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 6-10, 1st
Converter Schematic Diagram should be referred to if
additional signal tracing/fault isolation is necessary.
8. When the 1st Converter has been repaired and is
operating satisfactorily, deenergize the receiver and
disconnect test equipment, if no further tests are to be
performed.
Table 4-10. 1st Converter Fault Isolation Chart
Test Point
Normal Signal
Key Components
Comments
El
-20 dBm
Input cabling
Ul-4
-8 dBm FL1, Ul
E6
0 Vdc Digital control
AGC voltage
U6-6
+7 Vdc
U6
U2-4
-10 dBm
U2
U3-2
-15 dBm
U3 1st LO Signal
U5-4
-15 dBm
U5 1st IF Signal
E3 -6 dBm
U4
4-25