User Guide

PAMS
Technical Documentation
NHD–4
Disassembly & Troubleshooting
Page 44
Original 11/97
Hints and Suggestions
AMPS
•It is important to NOT adjust the tunable inductor L17. Doing so will
NOT assist in troubleshooting a faulty receiver, it will only make
things worse. This device is tuned by its manufacturer to the proper
inductance.
•While in AMPS Troubleshooting Mode, probe the 455 kHz ceramic filter
Z4. A noise pedastle approximatly 20 kHz wide will be visible about 10
dBm above the noise floor.
CDMA
•To determine in the CDAGCR IC (N1) quadrature demodulator is
functioning, connect both the RX_I and RX_Q to CH1 and CH2 of
oscilloscope. Put the scope in X–Y mode. A Lissajous pattern of a circle
should be displayed. Changing the received signal power should not
cause the size of the circle to change.