User Guide

Technical Documentation
NHD–4
System Module
P.A.M.S
Page 4–23
Original 11/97
Duplexor (Z102)
The Duplexor isolates the transmit signal from the receiver path and
permits the phone to transmit and receive signals simultaneously (i.e. Full
Duplex operation). The Duplexor is a three terminal, dual frequency (RX
and TX) bandpass splitter/filter and provides the common antenna
connection to the TX and RX circuits. The transmit signal enters the
Duplexor at the “TX” port and exits from the “ANT” port. The duplexor is
the largest device on the PCB and can be found on the TX schematic.
Thermister (R141)
The thermister R141 changes resistance as a function of its temperature.
The voltage across this device comprises the RFTEMP1 signal to the
MCU.