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RM-12
Synthesizer
troubleshooting
Yes
Set with RF controls:
Active Unti = Rx
Operation mode = Continuous
Check with RF probe:
-4G VCO out signal
- 3589.6 MHz (GSM900)
-3495.6 MHz (GSM1800)
- 3760 MHz (GSM1900)
Level >-10dBm (*
No
VCO out signal level<-10dBm
No
Check output signal on
1 GHz span
Signal found on
incorrect frequency ?
Yes
Check with oscilloscope:
VCO control voltage
from VCO pin
0V ?
No
Check with oscilloscope:
VCO control voltage
from VCO pin
>4.0 V ?
Issue 1 11/2004
Figure 7: Synthesizer troubleshooting diagram
*(When 2.5kOhm passive probe is used,
correct the measurement by +34 dB
Yes
Yes
OK ?
Check with oscilloscope:
-4G VCO Vcc = 2.7V
No
Yes
Check balun
output levels and
solder joints
OK ?
Check VCO control
loop components
COMPANY CONFIDENTIAL
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CCS Technical Documentation
Synthesizer
OK
Check balun
output levels and
solder joints
OK ?
No
Replace
faulty
component(s)
Yes
OK ?
No
No
Yes
OK ?
No
Yes
Replace
VCO
Yes
Replace
VCO
Baseband
troubleshooting
Replace
faulty
component(s)
29
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Troubleshooting
