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5HFHLYHU WURXEOHVKRRWLQJ GLDJUDP IRU *60
Apply –90dBm
1842.86771 MHz signal from
generator to antenna connector
Yes
Oscilloscope at RX_I
Signal 700mVpp
DC offset 1.35V
Frequency 67.7 kHz
Yes
GSM1800 RX
chain
functional
Synthesizer
troubleshooting
Note:
All spectrum analyzer
reading values are
measured with 1 kOhm
passive probe
(use tweezers to connect
the probe ground to the
nearest PWB ground)
Reading value is represented
without +26dB compensation.
*When 1kOhm passive probe is used,
correct measurement result by +26dB
3DJH
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Change
No
Yes
generator
level
to –50 dBm
Check
No
Z551,C555
C556, L551
Oscilloscope
No
VR4 2.7V
Check
Check HAGAR
baseband
serial interface.
(burst mode)
No
Yes
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Spectrum
Spectrum
No
analyzer
analyzer
1800 LNA out
1800 1st SAW
out
-61 dBm
Yes
Yes
Spectrum
analyzer
1800 bal out
-66 dBm
Oscilloscope
LNA_P 0V
LNAB_P 2.7V
Yes
Spectrum
analyzer
4G VCO out
3685.6 MHz
Spectrum
-30 dBm(*
analyzer
V550, RFout
-58 dBm
Check
No
HAGAR N600
Oscilloscope
V550, RFout 2.6V
V550, RFin 0.8V
Yes
Check
V550, C551
L552
Check
antenna switch
Z500
No
Spectrum
No
analyzer
1800_RX
-78 dBm
-77 dBm
Yes
Check
dual RX SAW
Z520
Check
baseband
No
Oscilloscope
VR4 2.7V
Check HAGAR
serial interface.
check R501
Yes
Check
HAGAR N600
Check
Yes
C552
Check
No
V550, R551,
L550, R558
,VVXH
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