User Guide

PAMS
Technical Documentation
WinTesla User Guide
NHD–4
Page 61
Original 11/97
LNA Gain Calibration Functionality Test
Manual Test
The LNA Gain Calibration process can be verified by performing the
associated procedure found in the tuning menu of the Service Software. It
can also be verified manually by performing the following steps:
1. Initiate the CDMA RX Quick Test from the test menu of the Service
Software
2. Into the CDMA RX feed a –65 dBm CW signal at 881.62 MHz
3.Turn the LNA on from this window
4. Read the received power to the CDSB ASIC, the RxCtr, by hitting the
“Test” button. Record this value.
5. Turn the LNA off
6. Again read the received power to the CDSB ASIC, the RxCtr, by hitting
the “Test” button. Record this value.
7. If the LNA is operating correctly the difference between the two
recorded values will fall between 120 and 160.
Troubleshooting
Fault with this calibration obviously points suspicion to the LNA
functionality. The CDMA RX may also be at fault. Also inspect the RF
switches N701 and N702 as well as the resistive attenuator located
between them. The Service Manual Receiver Troubleshooting section
and Functional Description will provide further information and test
suggestions to troubleshoot this fault.
CDMA TX Spurious Check
Definition of Test
This test reads spurious emissions levels of the CDMA Transmitter +/–
900 kHz from the center of the channel. For this test the phone is
transmitting at its maximum level in CDMA mode. This test can be
performed manually with a spectrum analyzer. To do this feed the 2180
RF output into the spectrum analyzer and set the CDMA TX output to
maximum. Service Software rails the CDMA TX to maximum for the
CDMA TX Quick Test. I recommend using it to put the phone into the
proper mode. Use the averaging functionality of the spectrum analyzer to
get readings of better precision. Set a marker + 30 kHz off the center
frequency of the transmit signal. Set another marker + 900 kHz off the
center frequency. The delta between them should be at least 26 dB. This
should also be done for – 30 and –900 kHz off center.