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Synthesizer troubleshooting
Set with RF Controls:
-Active Unit = Rx
Operation Mode = Continuous
Check with RF probe
4G VCO out signal
3769.6 MHz (GSM900)
3685.6 MHz (GSM1800)
Level>–10dBm *
OK?
No
VCO out signal level<-10dBm ?
No
Check output signal
on 1GHz span.
Signal found on
incorrect frequency ?
Yes
Check with oscilloscope
VCO control voltage
from VCO pin
0V ?
Yes
Check with oscilloscope
VCO control voltage
from VCO pin
>4.0V ?
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Yes
*When 1kOhm passive probe is used,
correct measurement result by +26dB
Yes
Check balun output levels
and solder joints.
OK ?
Check with oscilloscope
4G VCO Vcc=2.7V
No
OK?
No
Yes
Check balun output levels
and solder joints.
OK ?
Yes
Check VCO control loop
components.
OK ?
Yes
Replace
VCO
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Synthesizer OK
No
Replace
faulty components
No
No
Yes
1+0
Yes
Replace
VCO
Baseband
troubleshooting
Replace
faulty components
3DJH
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