Figure 4-5. Pa Test Adapter, 25/10 Watt Power Amplifier; Table 4-11. Power Control Dc Voltage Chart - Motorola ASTRO Digital Spectra Plus Service Manual

Troubleshooting Procedures: Power Amplifier Procedures
A+ TO COMMAND BOARD
CONTROL VOLTAGE LIMIT
CONTROL VOLTAGE DRIVE
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
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.
RX MODE
LOCATION
LOW
1 —
2
3
4 10.8 13.8
5 0
6 10.8 13.8
7
8 —
9
10 10.8 13.8
11 9.4
12 10.8
6881076C25-D
CURRENT SENSE +
1
K9.4

Figure 4-5. PA Test Adapter, 25/10 Watt Power Amplifier

Table

Table 4-11. Power Control DC Voltage Chart

TX MODE
TYP HI LOW TYP
— — — —
0 0 2.0
0 2.0 7.0
16.6 10.4 13.4
0 0 9.2 9.4
16.6 10.4 13.4
0 1.2
— — — —
0 1.5 3.5
16.6 10.4 13.4
9.6 9.9 9.4 9.6
9.8 13.1
2 4 6 8 10
3 5 7 9
4-11). Measure the indicated voltages. If they are not
HI
P0853
— Key (no pin or wire)
3.2 Control Voltage Limit
9.2 Control Drive Voltage
16.2 Current Sense +
9.8 Keyed 9.4
16.2 A+ to Command Board
Temp Sense (cutback begins at 3.3 V)
— Key (no pin)
5.0 Forward Detect Volt
16.2 A+ to Command Board
9.9 9.6-V Supply from Command Board
15.9 Current Sense - (voltage delta 150 mV)
A+ TO COMMAND BOARD
CURRENT SENSE -
12
11
FEMALE RECEPTACLE
CONNECTOR W 100 MIL
SPACING MATES TO P853
REGULATED 9.6V
V DETECT
TEMP SENSE
COMMENTS
October 28, 2002
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