Motorola APX 5000 Service Manual page 149

Troubleshooting Charts: RX RF Failure
RX RF Failure – Page 9
11
Measure control
voltage at TP602
Fvco too low?
<107.4 MHz
Yes
No
TP602 =
5 Vdc?
Yes
Remove Abacus
shield, SH6A, and
inspect second LO
VCO.
Visual
examination
OK?
Yes
Replace
Varactor
VR602
TP602(Vdc) TP601 (MHz) Fvco
0.00
1.47
4.16
5.00
No
TP602 = 0
Vdc?
Yes
10
Repair
No
defects
102.70
107.40
111.90
Remove IF filter shield,
112.80
SH2. Check IF filter and
LC matching networks.
No
10
Note: RF Test frequency used:
VHF: 154.275MHz
UHF1: 424.975MHz
UHF2: 485.075MHz
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.
12
No
Visual
inspection
OK?
Yes
Replace IF
filter, FL501.
5-43
Repair
Defects