September 5, 2008
6881076C25-E
4-42
Troubleshooting Procedures
: Power Amplifier Procedures
4.5.1.3.3 Localizing Problems
Failure locations often can be determined by externally measured symptoms. Basic symptoms are
noted below with probable failure locations.
1. Low Power and High Current
- Check for improper load conditions caused by high VSWR external to the radio.
- Check output coax and mini UHF connector.
- Check harmonic filter.
- Check output impedance-matching circuitry from the final device to the harmonic filter.
2. Low Power and Low Current
- If control voltage drive is equal to 8.0 V, then check per the above.
- It control voltage drive is less than 8.0 V, then check the control circuitry.
3. Power Intermittently Low (or Zero) and Current Less than 1 A. When Power Drops
- Check LLA stage.
33
4.0
5.0
0
0.2
TX PA Enable (from U520-25)
34
0
1.3
Control AMP one-shot
35
0
0
Lock (5-V of Synth Out of Lock)
36
0
0.8
Control AMP one-shot
37
10.8
13.6
16.3
10.0
13.0
16.0
A+ (Current Sense +)
38
10.8
13.6
16.3
10.0
13.0
16.0
Current Sense - Voltage Delta 150 mV (30 Watt
only)
39
0
9.2
9.4
9.8
Keyed 9.4-V in
40
1.5
3.0
4.5
1.5
3.0
4.5
Current Limit D-A (max current at 4.5 V)
41
0
0
0
0
0
0
Ground
42
0
2.2
9.6
Control AMP Output (Approx 1/2-V Control)
43
1.3
7.0
Loop Integrator Capacitor
44
2.1
3.2
Control AMP Reference
Q0500E
13.0
13.0
A+ - CR0500 Drop
Q0501C
12.3
12.3
VQ0500E - B/E Drop
Q0501E
0.2
0.2
V pin 23 - B/E Drop
Q0503E
0
1.5
V pin 42 - B/E Drop (TX)
Q0503C
13.6
9.0
Q0504B
13.6
12.9
A+ - B/E Drop (TX)
Table 4-15. Power Control DC Voltage Chart (Continued)
LOCATION
RX MODE
TX MODE
COMMENTS
LOW
TYP
HI
LOW
TYP
HI
Содержание ASTRO Digital Spectra
Страница 1: ...ASTRO Digital Spectra and Digital Spectra Plus UHF VHF 800 MHz Mobile Radios Detailed Service Manual ...
Страница 2: ......
Страница 6: ...September 5 2008 6881076C25 E iv Document History Notes ...
Страница 20: ...xviii List of Tables September 5 2008 6881076C25 E Notes ...
Страница 24: ...September 5 2008 6881076C25 E xxii CommercialWarranty Notes ...
Страница 48: ...September 5 2008 6881076C25 E xlvi Model Numbering Charts and Specifications Notes ...
Страница 142: ...September 5 2008 6881076C25 E 3 82 Theory of Operation Power Amplifiers Notes ...
Страница 218: ...September 5 2008 6881076C25 E 4 76 Troubleshooting Procedures Power Amplifier Procedures Notes ...
Страница 258: ...September 5 2008 6881076C25 E 6 14 Troubleshooting Waveforms ASTRO Digital Spectra Plus VOCON Board Waveforms Notes ...
Страница 434: ...September 5 2008 6881076C25 E Glossary 10 Notes ...
Страница 440: ...Index 6 September 5 2008 6881076C25 E Notes ...
Страница 441: ......