Localizing Problems; Table 4-21. Antenna Switch Dc Voltage Chart - Motorola ASTRO Digital Spectra Plus Detailed Service Manual

Troubleshooting Procedures: Power Amplifier Procedures
RX MODE
LOCATION
LOW
43
44
Q0500E 13.0
Q0501C 12.3
Q0501E
Q0503E
Q0503C 13.6
Q0504B 13.6
NOTE: For antenna switch transmit bias conditions, RF drive must be removed from PA.
LOCATION
CR5920
CR5921
CR5922

4.5.2.2.3 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 and J-straps for opens and/or shorts.
- Check output impedance-matching circuitry from the final device to the harmonic filter.
2. Low Power and Low Current
- If control voltage is equal to 10.0 V, then check per the above.
- If control voltage is less than 10.0 V, then check the control circuitry.
6881076C25-E
Table 4-20. Power Control DC Voltage Chart (Continued)
TX MODE
TYP HI LOW TYP
1.3 7.0
2.1 3.2
13.0
12.3
0.2 0.2
0 1.5
9.0
12.9

Table 4-21. Antenna Switch DC Voltage Chart

TYPICAL RX
ANODE 0
CATHODE 0
ANODE 0
CATHODE –
ANODE 0
CATHODE –
COMMENTS
HI
Loop Integrator Capacitor
Control AMP Reference
A+ - CR0500 Drop
VQ0500E - B/E Drop
V pin 23 - B/E Drop
V pin 42 - B/E Drop (TX)
A+ - B/E Drop (TX)
TYPICAL TX
NO PRE- COMMENTS
DRIVE
1.6
0.8
0.8
–
<0.8
–
4-61
September 5, 2008