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NHM-7
Troubleshooting and Tuning Instructions
PAMS Technical Documentation
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Receiver troubleshooting diagram for GSM1800
Receiver troubleshooting diagram for GSM1800
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Apply –90dBm
1842.86771MHz signal
from generator to anten-
na connector
Oscilloscope at RX_I
Signal 700mVpp
DC offset 1.35V Fre-
quency 67.7kHz
Change ge-
nerator level
to –50dBm
Spectrumanalyzer
1800 LNA out
–61 dBm
Spectrumanalyzer
1800 1st SAW out
–77 dBm
GSM1800 RX chain
functional
Spectrumanalyzer
1800 bal out
–66 dBm
Oscilloscope
VR4 2.7V
Check Hagar serial
interface (burst mo-
de)
Check Z551, C555,
C556, L551
Check Baseband
Spectrumanalyzer
4G VCO out
3685.6MHz
∼
–30 dBm (*
Synthesizer troubles-
hooting
Check Hagar N600
Oscilloscope
LNA_P 0V
LNAB_P 2.7V
Spectrumanalyzer
V550,
RFout –58 dBm
Check C552
Oscilloscope
V550, RFout 2.6V
V550, RFin 0.8 V
Check V550, C551,
L552
Check V550,
R551, L550,
R558
Oscilloscope
VR4 2.7V
Check Hagar seri-
al interface (burst
mode)
Check Hagar
N600
Check Base-
band
Spectrumanalyzer
1800_RX
–78 dBm
Check An-
tenna switch
Z500
Check dual RX SAW
Z520
* Spectrumanalyzer
reading with 1 kohm
passive probe (right val-
ue add +26 dB)
All spectrumanalyzer 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 w26
dB compensation.