Troubleshooting Charts:
RX RF Failure
5-35
RX RF Failure – Page 6
Check LNA:
Check DC bias voltages for U406 at
the base (pin 1) & collector (pin 3).
Is base voltage =
0.778 V? and
collector voltage =
1.554 V?
Check DC bias voltages of Q402 at
the base (pin 2 or 5) , collector (pin
6) & emitter (pin 1).
Is base voltage = 1.024
V? Collector voltage =
0.777 V? Emitter
voltage = 1.554 V?
Check DC input line voltages
and visually inspect and
replace defective
components if needed.
No
Yes
No
Yes
Replace
U406
Replace
Q402
Check LNA:
Check DC bias voltages for U407 at
the base (pin 1) & collector (pin 3).
Is base voltage =
0.778 V? and
collector voltage =
1.552 V?
Check DC bias voltages of Q403 at
the base (pin 2 or 5), collector (pin
3) & emitter (pin 4).
Is base voltage = 1.025
V? Collector voltage =
0.778 V? Emitter voltage
= 1.552 V?
Check DC input line voltages
and visually inspect and
replace defective
components if needed.
No
Yes
No
Yes
Replace
U407
Replace
Q403
6
7
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.
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: ......