5-30
Troubleshooting Charts:
RX RF Failure
5.11 RX RF Failure – Page 1
Inject a carrier wave with -47dBm
into antenna port. Remove shield,
SH2. Use a spectrum analyzer
and high-impedance RF probe to
measure the IF signal at the input
side of C601 going to the Abacus.
IF Frequency =
109.65 MHz?
Poor RX
sensitivity or
no RX audio
No
No
Is the IF signal level at the
input side of C601 about:
700: -50 dBm?
800: -55 dBm?
UHF1/UHF2: -50 dBm?
VHF: -50 dBm?
Yes
1
Yes
Remove shield, SH7. Measure RF levels at
the input side of L1117 and the input side of:
C2705 (for VHF radios), C2605 (for UHF1/UHF2 radios),
or C2305 (for 700/800 radios).
Compute the Harmonics Filter and Antenna Switch loss.
No
Remove SH10.
Measure the LO
power going into the
mixer, U507, at the
output side of R525.
Is the LO power
= -3 dBm?
Check FGU and
replace U507 if
needed.
Yes
Note:
RF Test frequency used:
VHF: 154.275MHz
UHF1: 424.975MHz
UHF2: 485.075MHz
700: 769.0625MHz
800: 860.0625MHz
Measured with a High Frequency Probe for relative comparisons and troubleshooting only.
Actual S21 gain or loss may differ if the test point is not 50 ohms.
Loss < 1.5 dB?
Measure RF levels at the input side of C2705 and pin 3 of U2702
(for VHF radios), C2605 and pin 3 of U2602 (for UHF1/UHF2 radios) or
the input side of C2305 and pin 3 of U2302 (for 700/800 MHz radios)
Compute the 15dB step attenuator U2602 or U2302 loss.
Note: The 15dB step attenuator will be enabled
Yes
Loss <17dB?
No
Testing a
UHF1/UHF2/
VHF?
Testing a
700/800 MHz
radio?
Testing a
700?
No
Yes
Yes
2
No
3
4
Remove shield SH8.
Visual inspect the Harmonics Filter and
Antenna Switch components and replace
parts if needed
No
Yes
Check digital logic to the 15dB Step
Attenuator and replace U2702
(for VHF radios), U2602
(for UHF1/UHF2 radios), or U2302
(for 700/800 MHz radios) if needed
Yes
Summary of Contents for APX 2000
Page 1: ...APXTM TWO WAY RADIOS APX 1000 APX 2000 APX 4000 APX 4000Li DETAILED SERVICE MANUAL ...
Page 4: ......
Page 6: ...iv Document History Notes ...
Page 8: ...Notes vi Commercial Warranty ...
Page 10: ...Notes ...
Page 22: ...xiv List of Figures Notes ...
Page 226: ...6 64 Troubleshooting Waveforms LF CW on Spectrum Analyzer Notes ...
Page 688: ...Index 4 Index Notes ...
Page 690: ...ii Notes ...
Page 700: ...xvi List of Figures Notes ...
Page 806: ...5 50 Troubleshooting Charts PA Failure Notes ...
Page 1008: ...8 178 Schematics Boards Overlays and Parts Lists Transceiver RF Boards UHF2 84012621001 Notes ...
Page 1062: ...8 234 Schematics Boards Overlays and Parts Lists Keypad Board M2 and M3 PC000261A01 Notes ...
Page 1064: ...ii Notes ...
Page 1068: ...Notes A 4 EMEA Warranty Service and Technical Support Further Assistance From Motorola ...
Page 1090: ...Glossary 10 Glossary Notes ...
Page 1094: ...Index 4 Index Notes ...
Page 1095: ......