Gsm Tx Tunings - Nokia RH-13 Series Troubleshooting Manual

RH-13
Troubleshooting
If NTC temperature fails it might be due to:
- Faulty NTC resistor or pull-up resistor
- faulty UEM
- wrong ambient temperature (phone is too hot or cold)
GSM RX CROSS BAND CALIBRATION
- Purpose of the calibration is to compensate gain ripple due to rx-filters over the band
- This is done in UB and LB
If it fails, response over the band can be very bad and there can be following problems:
- Please check that all components are ok and in place around rx-parts
- Please check that filters are ok

GSM TX tunings

If some TX tuning fails, start always TX troubleshooting!
TX IQ
Purpose of this tuning is to tune DC offset and phase offset so low as possible
- Typical values: Amplitude: -45 to –55 dBc, and Phase: –50 to – 60 dBc
If tuning fails there can be following problems:
- UEM or Safari
- Too low output power
TX Power levels
Purpose of this tuning is to tune all power levels GSM1900 (PL0 – PL15)
and GSM850 (PL7 – PL19)
If tuning fails there can be following problems:
- Broken components: PA, Safari, up converter, some filters
- Missing components
TX crossband
Page 74 ãNokia Corporation
CCS Technical Documentation
Issue 1 11/02