Tx1800/1900 Gmsk Troubleshooting; Fig 6 Tx 1800/1900 Gmsk Troubleshooting - Nokia RM-14 Rf Troubleshooting And Manual Tuning

RM-14
RF Troubleshooting and Manual Tuning
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Tx 1800/1900 GMSK troubleshooting

TX1800/1900 GMSK troubleshooting

Apply a 50 ohm load at the antenna connector of the jig.
GSM1800 ch. 700 = 1747,8 MHz, burst mode power level 5
GSM1900 ch. 661 = 1880,0 MHz, burst mode power level 5
Spectrum analyzer RBW = 500 kHz and VBW = 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 at L505
Measure RF level = -15 dBm at input of T700 Tx balun C714
Measure RF level = -10 dBm at N700 PA input R707 pin1
Measure RF level = -3 dBm at N700 PA output TX_OUT_DCS (Z800)
Measure N700 PA power detector DET = 810 mV during burst at R701.
Note: DET voltage is a function of power level
Measure N700 PA control voltage a) VPCTRL_1800/1900 = 1.0 V during burst at R715
and N700 PA bias voltage and N700 PA bias voltage
b) VTXB_1800/1900 = 2.7 V (C709).
Note: VPCTRL_1800/1900 voltage is a function of power level.
Measure N700 PA supply voltage VBAT at C705
Measure RF level = 2 dBm at antenna pad J124
Measure Z800 antenna switch control signal voltages
a) VANT_1 = 0 V at C811
b) VANT_2 = 2.7 V at C809
c) VANT_3 = 2.7 V at C810
ISSUE 1 11/04
Figure 6:TX 1800/1900 GMSK troubleshooting
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Check
baseband.
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Check
N500 Helgo.
Check T700
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Tx balun.
OK
11