Motorola APX 5000 Service Manual page 147

Troubleshooting Charts: RX RF Failure
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?
Yes
8
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.
Visually inspect and
No
replace components if
necessary.
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.
Yes
14
5-41
No
13