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Table 4-4.
WJ-8718-19/FE HF Receiver Troubleshooting Procedures. (Cont'd
Step
a.
b.
a .
Fault
MAN GAIN
range is
<100 dB
AGC control
range is
<80 dB.
IF output
freq. error
>100 Hz.
Probable Cause
Faulty A4A6
Faulty A4A6
Time Base
misadjusted.
Additional Test
Check AGC outputs
for correct swing as
RF Gain is rotated
CCW to CW: A4A6-47,
0 to -3.5 V, A4A6-19,
0 to +0.8 V.
Check input to AGC at
A4A6-51:
2 Vdc.
With receiver and sig.
gen. tuned to 29.99990
MHz, adjust A5A1U14
for 0 Hz error in IF
output.
Repeat step 7,
Table 4-3.
Corrective Action
If either output is
incorrect check or
replace A4A6.
If
both outputs are
correct, check A3,
then check A4A7.
If correct, replace
A4A6.
If incorrect,
receiver gain is
low.
Repeat step 3,
Table 4-3.
If receiver still
fails test, check
BCD presets to
A5A1 and A5A2 at
00.50000 and
29.99990 MHz re
ceiver tuned fre
quencies.
If cor
rect, replace A5A1
or A5A2.
If incor
rect,
replace A6A1
then A6A2.
4-15
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