
6881076C25-E
September 5, 2008
Troubleshooting Procedures
: Power Amplifier Procedures
4-31
Figure 4-5. PA Test Adapter, 25/10 Watt Power Amplifier
4. With the applied control voltage drive initially at 0 V, slowly increase the voltage until power
out equals 28 Watts. Power should rise smoothly with control voltage once the turn-on
threshold is reached. Control voltage drive should not exceed 9.2 V.
5. If 9.2 V does not produce 28 Watts, then a failure exists in the power amplifier circuit.
6. Refer to the voltage chart (see
Table 4-11
). Measure the indicated voltages. If they are not
within the limits shown in the chart, then a failure exists in the PA assembly.
7. If the voltages in the chart are correct, verify that the injection is at least 10 mW. (See the
VCO troubleshooting section.)
8. If no failure is located from the previous checks, troubleshoot the power control circuitry.
Table 4-11. Power Control DC Voltage Chart
LOCATION
RX MODE
TX MODE
COMMENTS
LOW
TYP
HI
LOW
TYP
HI
P0853
1
–
–
–
–
–
–
Key (no pin or wire)
2
0
0
2.0
3.2
Control Voltage Limit
3
0
2.0
7.0
9.2
Control Drive Voltage
4
10.8
13.8
16.6
10.4
13.4
16.2
Current Sense +
5
0
0
0
9.2
9.4
9.8
Keyed 9.4
6
10.8
13.8
16.6
10.4
13.4
16.2
A+ to Command Board
7
0
1.2
Temp Sense (cutback begins at 3.3 V)
8
–
–
–
–
–
–
Key (no pin)
9
0
1.5
3.5
5.0
Forward Detect Volt
10
10.8
13.8
16.6
10.4
13.4
16.2
A+ to Command Board
11
9.4
9.6
9.9
9.4
9.6
9.9
9.6-V Supply from Command Board
12
10.8
9.8
13.1
15.9
Current Sense
–
(voltage delta 150 mV)
A+ TO COMMAND BOARD
CURRENT SENSE +
A+ TO COMMAND BOARD
CURRENT SENSE -
CONTROL VOLTAGE LIMIT
CONTROL VOLTAGE DRIVE
K9.4
FEMALE RECEPTACLE
CONNECTOR W 100 MIL
SPACING MATES TO P853
REGULATED 9.6V
V DETECT
TEMP SENSE
8
6
4
2
10
12
7
5
3
1
9
11
Summary of Contents for ASTRO Digital Spectra
Page 2: ......
Page 6: ...September 5 2008 6881076C25 E iv Document History Notes ...
Page 20: ...xviii List of Tables September 5 2008 6881076C25 E Notes ...
Page 24: ...September 5 2008 6881076C25 E xxii CommercialWarranty Notes ...
Page 48: ...September 5 2008 6881076C25 E xlvi Model Numbering Charts and Specifications Notes ...
Page 142: ...September 5 2008 6881076C25 E 3 82 Theory of Operation Power Amplifiers Notes ...
Page 434: ...September 5 2008 6881076C25 E Glossary 10 Notes ...
Page 440: ...Index 6 September 5 2008 6881076C25 E Notes ...
Page 441: ......