Watkins-Johnson Company WJ-8718-19/FE Instruction Manual page 167

MAINTENANCE
WJ-8718-19/FE HF RECEIVER
Table 4-4. WJ-8718-19/FE HF Receiver Troubleshooting Procedures. (Cont'd)
Step
d.
e.
f.
5. a.
4-14
Fault
Line Audio
Output dis
torted.
(AM Mode)
No 400 Hz ton
in earphone
(CW Mode)
No 400 Hz
tone in
earphone
(USB)
No 400 Hz
tone in
earphone,
(LSB Mode)
*Jo Phone
Audio Out-
)Ut.
.ow SNR.
Probable Cause
Faulty A4A10
Faulty A4A9
Faulty A6A2
Faulty A5A3
7aulty A6A2
7aulty A4A10
faulty RF Filter
•aulty A3
Additional Test
Check Audio Signal at
A4A9-57. 0.7 Vrms
at 400 Hz.
Check BFO Signal at
A4A9-17: 454.600 kHz
at 40 mV.
Check CW/SSB Select
voltage, A4A9-43:
3 Vdc in CW mode.
Check USB Select Volt
ages at A4A2-45 (DF),
A4A9-43 (SSB): +3 Vdc
in selected modes.
Check BFO Signal at
A4A9-17: 455.000 kHz
at 40 mV.
heck 1st and 2nd LO
signals for adequate
evels:
st LO: +20 dBm
fend LO: 0 dBm
Corrective Action
Replace A4A10. If
problem not correc
ted, check +24 V at
Jl-5.
If correct, replace
A4A10. If in
correct, perform
next test.
If incorrect, check
or replace A5A3.
If incorrect,
perform next test.
If incorrect, check
or replace A6A1
then A6A2. If
correct, replace
A4A9.
If incorrect, check
or replace A6A2.
If correct, perform
next test.
If incorrect, check
or replace A5A3.
If correct, check
A4A9.
Check or replace
A6A1 then A6A2.
Check or replace
A4A10.
Check or replace
RF Filter.
If incorrect, re
place A5A1 or A5A2
If correct, replace
A3 and repeat Step
5, Table 4-3.