Troubleshooting Charts: RX RF Failure 5-41
RX RF Failure – Page 7
5
Remove shield, SH7.
Measure RF levels at the
filter and compute filter
loss. Input side of C526
and output side of C503.
Filter Loss
<1 dB?
8
Visually inspect and
replace components if
necessary.
No
Yes
8
Remove SH5A and SH2.
Measure RF and IF level at
mixer and compute mixer
conversion loss. Pin 1 of
T503 and Pin 1 of T504.
Mixer loss
about 6dB?
Levels between
4-8 dB are
acceptable.
No
Yes
13
14
Note: RF Test frequency used:
VHF: 154.275MHz
UHF1: 424.975MHz
UHF2: 485.075 MHz
700: 769.0625MHz
800: 860.0625MHz
Measured with a high impedance probe for
relative comparisons and troubleshooting only.
Actual S21 gain or loss may differ if the
test point is not 50 ohms.
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