User Manual
SERVICING
5-4
June 1997
Part No. 001-3412-002
5.4.4 FINAL AMPLIFIER (U521)
1. Check the voltages on U521.
Pin 2 = 5.5V DC (varies with power setting)
Pin 3 = 5.0V DC
Pin 4 = 12.7V DC
Power output at C551 should be 7.5-8.0W (+38.7 to
+39 dBm).
5.4.5 ANTENNA SWITCH (CR561/CR562)
1. Check the antenna switch voltages.
CR561 = 8.6V DC
CR562 = 8.0V DC
The loss through the Antenna Switch should be 1.9
to 2.1 dB.
5.4.6 MODULATION INPUT (J201, PIN 6)
1. Check for audio/data signals at J201, pin 6, Y801,
pin 1 and A801, pin 3.
5.4.7 TCXO (Y801)
1. Check Y801, pin 1 for 2.5V DC ±1%.
2. Adjust Y801 to set the transmitter to the frequency
of operation.
3. If the frequency cannot be set to the frequency of
operation, replace the TCXO.
Figure 5-2 TRANSMITTER SERVICING
START
MEASURE
CURRENT AND
OK
?
NO
YES
MEASURE RF
WATTS
?
CHECK DEVIATION
TRANSMITTER
OK
OK
?
OK
?
NO
NO
NO
YES
YES
YES
WIRE HARNESS CONNECTIONS
CHECK FUSES AND
CHECK AUDIO
CHECK TCXO
ADJUST OR
CHANGE TCXO
OFF FREQ
5
VOLTAGES
OUTPUT POWER
(SECTION 5.4.6)
CIRCUITS
CHECK FREQUENCY
(SECTION 5.4.7)
Y801
OK
?
NO
YES
CHECK Q501
REFER TO
CHECK PRE-DRIVER
OK
?
NO
YES
CHECK A801
REFER TO
SECTION 5.4.2
CHECK DRIVER
SECTION 5.4.3
CHECK Q511
OK
?
NO
YES
REFER TO
CHECK
POWER MODULE
SECTION 5.4.4
CHECK U521
OK
?
NO
REFER TO
CHECK
ANTENNA SWITCH
SECTION 5.4.5
CHECK
CR561/562