User Guide

PAMS
Technical Documentation
WinTesla User Guide
NHD–4
Page 29
Original 11/97
AMPS Tuning
Analog Bias Current Tuning
The purpose of this tuning is to optimize transmitter‘s efficiency.
Bias tuning is needed if:
– PLL circuit (N500) is replaced
– Any of the power amplifiers V110, V111, V112, V113 or the duplex filter
is replaced
– Any of power amplifier resistors are replaced
This affects only power consumption and thus gain and linearity of power
amplifier.
Description of Tuning
This tuning sets the bias current to the CLY–10 (V113) final PA gain stage
for AMPS mode operation at output power level 7. The TXB PDM is used
to set this bias. The bias is set to provide 100 mA of current to the
CLY–10 in this state. This 100 mA current is the amount of current draw
above the quiescent state of the phone in AMPS mode, as described in
the AMPS Mode Quiescent Current section 3.1. Note that the CLY–10 will
draw additional current at higher output AMPS power levels. This is due
to self biasing by the drive signal.
Analog bias current tuning 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.
– Start the service software and go to ”Main” menu.
– Select ” Tuning – Analog Bias Tuning ”
– Measure step1 current consumption from power supply current display
and input it to Service software prompt. Then press OK.
– Adjust first analog mode bias current to the target value displayed in
tuning dialog by using Arrow keys or PgUp/PgDn keys.