User Guide

PAMS
Technical Documentation
NHD–4
Disassembly & Troubleshooting
Page 33
Original 11/97
CDMA TX Output
RF Signal Level
(dBm)
TX_GAIN Voltage
at C213
(V)
TX_ICT Control
Current
(mA)
TX_ICT
(as voltage drop
across R116)
(mV)
15 1.78 0.700 70.0
10 1.80 0.560 56.0
–5 1.87 0.298 29.8
–20 1.93 0.171 17.1
–35 2.00 0.093 9.3
Testing Auxiliary AGC
To test the gain control abilities of the Auxiliary AGC feature, perform the
following steps:
1. Place the phone in the CDMA Troubleshooting Mode
2. Observe the TX output with a spectrum analyzer or CDMA test set. Be
sure to read bandpower over a 1.23 MHz band.
3. Use the CDMA TX manual gain control found in the Service Software to
adjust the output power of the phone from 15 dBm to 23 dBm.
4. Observe the VC voltage at C109 and the AGC_REF PDM voltage at
C716. The table below details approximate values that should be read.
CDMA TX
Output Power
(dBm)
AGC_REF PDM
(decimal value)
AGC_REF PDM
voltage at C716
(V)
VC
at C109
(V)
23 0 0.798 3.28
21 34 0.583 2.81
19 60 0.456 2.53
17 79 0.367 2.33
15 85 0.333 2.26
Hints and Suggestions
The 3rd stage (V112) is sensitive to shorts of the DC bias line.
Accidentally shorting the collector to ground always blows the 5.6 ohm
bias resistor (R117) but doesn’t harm the transistor.