User Guide

PAMS
Technical Documentation
WinTesla User Guide
NHD–4
Page 43
Original 11/97
Align TX Gain Limiting Tuning
The purpose of this tuning operation is to calibrate the Maximum Power
output in CDMA mode.
This tuning is needed if the Power Amplifier (V113) or surrounding
components of is changed .
Definition of Tuning
This tuning sets the upper limit on the output power of the CDMA TX. To
do so, the CDMA TX is initially railed high, providing the maximum output
power that the phone’s software will allow it to produce. This output
power is then reduced until it is approximately 24.5 dBm. This is
accomplished by decreasing the value of the TXI_REF PDM. The value
of TXI_REF PDM determines the TX limit by comparing itself to the TXI
voltage generated by the detector. It is important to keep in mind that this
24 dBm value refers to power within the 1.23 MHz CDMA channel band.
Thus it is a bandpower measurement, not a peak power measurement.
TX Offset calibration steps & equipment:
– Using the JBS–7 service jig, replace the standard battery of the phone
with the dummy battery BTS–4.
– Apply +6.0 V to dummy battery.
– Connect the modulation (or spectrum) analyzer to antenna connector
and measure transmitter frequency. Adjust frequency to 838.20 MHz +
– 200Hz with arrow or PgUp/PgDn –keys.
– Select ” Tuning – TX Maximum Gain”
– Adjust tuning value with arrow keys (fine tuning) or with PgUp and
PgDn–keys (coarse tuning) until measured Power level is within the
Target value.
– Press <save & exit> to store value to EEPROM or <cancel> to exit
without saving.