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Apply –90dBm
1842.86771MHz signal
from generator to anten-
na connector
1842.86771MHz signal
from generator to anten-
na connector
Oscilloscope at RX_I
Signal 140mVpp
DC offset 1.35V ***
Frequency 67.7kHz
Signal 140mVpp
DC offset 1.35V ***
Frequency 67.7kHz
Change ge-
nerator level
to –50dBm
nerator level
to –50dBm
Spectrumanalyzer
Antenna switch out-
puts,
1800 LNA out
–61 dBm
Antenna switch out-
puts,
1800 LNA out
–61 dBm
Spectrumanalyzer
Antenna Swithc input
-84 dBm
GSM1800 RX chain
functional
functional
Oscilloscope
VR1,3...6 2.7V
Check HELGA serial
interface
(burst mode)
VR1,3...6 2.7V
Check HELGA serial
interface
(burst mode)
Check C838, C839,
L821. L 872,
C836, C837,
V801
L821. L 872,
C836, C837,
V801
Oscilloscope
VANT_1...3 0V
VANT_1...3 0V
Oscilloscope
Check HELGA se-
rial interface (burst
mode)
Check HELGA se-
rial interface (burst
mode)
Check HELGA
N600
N600
Check Base-
band
band
* Spectrumanalyzer
reading with 1 kohm
passive probe (right val-
ue add +26 dB)
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 without +26
dB compensation.
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 +26
dB compensation.
Check C831,
L811
L811
Check Antenna
Switch Z800
Switch Z800
Spectrumanalyzer
HELGA inputs
GSM 1800
–88 dBm
HELGA inputs
GSM 1800
–88 dBm
Check Base-
band
band
No
Synthesiszer trou-
bleshooting
bleshooting
Spectrumanalyzer
4G VCO out
3769.6MHz
4G VCO out
3769.6MHz
∼
–30 dBm (*
Yes
Check HELGA
N500
N500
* ** DC–level of RXI/RXQ in
continuous mode will decrease
slowly.
The original level can be resto-
red by rewriting gain set.
continuous mode will decrease
slowly.
The original level can be resto-
red by rewriting gain set.