10.7 Mhz Filter Switch Fault Isolation Chart - Watkins-Johnson Company WJ-8718-19/FE Instruction Manual

MAINTENANCE
WJ-8718-19/FE HF RECEIVER
Table 4-12. 10.7 MHz Filter Switch Fault Isolation Chart.
Test Point
Normal S
ignal
Key Components
Comments
Cl/Ll
33 mV
at
10.7 MHz CI, LI
All BW positions •
Ql-C
110 mV
at 10.7 MHz
Ql
Select 3.2 kHz
BW
FL1-OUT 65 mV
at 10.7 MHz
FL1
Q4-B
12 mV
at 10.7 MHz
R26, Q4
Q2-C
120 mV
at 10.7 MHz
Q2
Select 6 kHz BW
FL2-OUT
65 mV at 10.7 MHz
FL2
Q5-B
10 mV at
10.7 MHz R28, Q5
Q3-C
90 mV
at 10.7 MHz
Q3
Select 50 kHz
Q6-B
10 mV
at 10.7 MHz R30, Q6
Al-57
•
50 mV
at 10.7 MHz Q4, Q5, Q6, Ul, U2
All BW positions
4-3-4'14 10.7 MHz/455 kHz Converter, A4A2, (794254) Testing and Troubleshooting
. , 10n7 MHz/455 kHz Converter Testing and Troubleshooting includes a
checkout procedure and fault isolation information. A Signal Generator and an RF
Voltmeter (Table 4-1) are required to perform the tests outlined below.
Perform the following in the sequence given. If any specified result is
not obtained, refer to Table 4-13 for fault isolation.
4-30
1.
2.
3.
4.
Deenergize the receiver.
Place PC board A4A2 on an extender. Remove PC board
A4A1.
Connect the RF Voltmeter to A4XA2 pin 19 using a
short coaxial cable with clip leads on one end. Connect
cable shield to the IF Motherboard ground plane.
Connect the Signal Generator RF output to A4XA2
pin 57 using a short coaxial cable with clip leads on
one end. Connect cable shield to the IF Motherboard
ground plane. Set the Generator output frequency to
10.7 MHz and output level to -27 dBm.