Tx 900 Gmsk Troubleshooting; Fig 5 Tx 900 Gmsk Troubleshooting - Nokia RM-14 Rf Troubleshooting And Manual Tuning

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Tx 900 GMSK troubleshooting

TX850/900 GMSK troubleshooting
Apply a 50 ohm load at the antenna connector of the jig.
GSM900/ cha. 37 = 897.4 MHz, burst mode power level 10
Spectrum analyzer: RBW = 500 Khz and VBW = 500 kHz,
center = 500 kHz and span = 20 MHz
Measure voltage of a) TXI at C529 and TXQ at C530,
Txi and TXQ = 500 mVpp min. and 1.4 VDC during burst
Measure a) TXC = 800 mV during burst at R514 and
b) TXP = 1.8 V during burst at J504 .
Note: TXC voltage is a function of power level
Measure modulator supply voltage VR2 = 2.7 V (C511, both terminals)
Measure RF level = -13 dBm at input of Z700 SAW filter C702
Measure RF level = -13 dBm at N700 PA input (R704 pin1)
Measure RF level = +10 dBm at N700 PA output TX_OUT_EGSM
(Z800 pin1)
Measure N700 PA power detector DET = 850 mV during burst at R701.
Note: DET voltage is a function of power level
Measure N700 PA control voltage a) VPCTRL_G = 1.2 V during burst at
R713 and N700 PA bias voltage.
b) VTXB_G = 2.7V (C701).
Note: VPCTRL_G voltage is a function of power level.
Measure N700 PA supply voltage VBAT at C705
Measure RF level = 20 dBm at antenna pad J124
Measure Z800 antenna switch control signal voltages
a) VANT_1 = 2.7 V at C811
b) VANT_2 = 0 V at C809
c) VANT_3 = 2.7 V at C810
10
Figure 5:TX 900 GMSK troubleshooting
TX 900 GMSK troubleshooting
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RF Troubleshooting and Manual Tuning
NOK
NOK
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OK
RM-14
Check
baseband.
Check
N500 Helgo.
Check Z700
Tx SAW.
ISSUE 1 11/04