Kenwood TKR-740 Service Manual page 41

5.6 Baseband circuit
The baseband circuit sw itches betw een the modulation
signal to the transmitter unit, demodulation signal from the
receiver unit, and remote audio signal and adjusts their levels.
This circuit consists of IC12, IC13, IC14, IC29, IC32, IC33, IC36,
IC37 and IC40. M odulation inputs include local microphone
input, low -speed data (LSD), high-speed data (HSD), external
audio input (TA), ext ernal dat a input (TD), and rem ot e
CIRCUIT DESCRIPTION
modulation input (RTA), and demodulation outputs include
receive audio output (RA), receive data output (RD), and remote
receive audio (RRA). The multiplexer (IC14, IC29, IC37)
changes signals, the electronic volume control (IC33) adjusts
the level, and the operational amplifier (IC12, IC13, IC32, IC36,
IC42) amplifies and sums signals.
Fig.26 Baseband circuit
TKR-740
41