Localizing Problems; Table 4-25. Antenna Switch Dc Voltage Chart - Motorola ASTRO Digital Spectra Plus Detailed Service Manual

Troubleshooting Procedures: Power Amplifier Procedures
LOCATION
CR9920
CR9921
CR9922
Q9920

4.5.3.1.3 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.
- Check output impedance-matching circuitry from the final device to the harmonic filter.
2. Low Power and Low Current
- If control voltage is greater than 10 V, then check per the above.
- If control voltage is less than 10 V, then check the control circuitry.
3. Power Intermittently Low (or zero) and Current less than 1 A. when Power Drops
- Check Buffer Stage.
4. Power Zero and Current greater than 5 A.
- Check harmonic filter, antenna switch, and matching circuits beyond final stage.
5. Power Zero and Current between 2 and 5 A.
- Check Power Module.
6. Power Zero and Current less than 1 A.
- Check input coax.
- Check Buffer Stage.
6881076C25-E

Table 4-25. Antenna Switch DC Voltage Chart

TYPICAL RX
ANODE 0
CATHODE 0
ANODE 0
CATHODE –
ANODE 5.15V
CATHODE 4.45V
COLLEC 5.15V
TYPICAL TX
NO PRE- COMMENTS
DRIVE
1.6 TX Series P.I.N. diode
0.8 (on in TX mode)
0.8
TX Shunt P.I.N. diode
– (on in TX mode)
<0.2 RX Series P.I.N. diode
8.7
(off in TX mode)
<0.2
4-71
September 5, 2008