Kenwood NX-203 Service Manual page 16

NX-203
F400
2.5A
IC400
/SAVE
AVR
/5TC
5RC
IC403
SBC
AVR IC
Q403
SB3 SW
CN400
CN404
IC411
5UC
AVR IC
Q403
SBC
SB2 SW
IC708
AVR IC
IC416
AVR IC
IC407
DC/DC
IC414
Detect
SB1
VOL SW
Q408
AND
D408
OR
Fig. 8 Power supply circuit
16
CIRCUIT DESCRIPTION
TX-RX unit (X57)
+B RF Final AMP
APC
50C
VCO
50T
Q405
TX circuit
50T SW
50R
Q401
RX circuit
50R SW
50IF
Q402
IF circuit
50IF SW
33C
PLL, VCTCXO
SB3
TX/Busy LED
150C
IC402
Assist, Tune
DC/DC
Control unit (X53)
50U
Universal
SB2 BackLight
Key Light
5A
Option
-10V
IC403
LCD Bias
DC/DC
31BU
Q409
SRAM, RTC
31BU
33M ASIC, DSP I/O,
IC404
Flach, LCD DRV
AVR
15M
IC717
ASIC, DSP core
DC/DC
33A ASIC Analog,
IC406
Audio
AVR
/PSW
Q402 IC108
Lvl Conv ASIC
/BINT
Q401
Lvl Conv
D412
SBC
OR
8. Signaling Circuit
8-1. Encode (QT/DQT/LTR/DTMF/2-tone/MSK)
Each signaling data signal of QT, DQT, LTR, DTMF , 2-tone
and MSK is generated by the DSP circuit, superposed on
a modulation signal and output from IC108. The modula-
tion balance of the QT/DQT/LTR signal is adjusted by the D/
A converter(IC703) and the resulting signal is routed to the
modulation input of the VCO and VCXO (X1). Each deviation
of the TX QT, DQT, LTR, DTMF , 2-tone and MSK tone is ad-
justed by changing the output level of IC108 and the result-
ing signal is routed to the VCO and VCXO. The RX DTMF
tone is routed to the receive audio signal system, and is
output from the speaker.
8-2. Decode (QT/DQT/LTR/DTMF/2-tone/MSK)
The audio signal is removed from the FM detection
signal sent to the DSP circuit and the resulting signal is de-
coded.
9. Compander Circuit
The term "compander" means compressor and expand-
er. The compander reduces noise by utilizing a compressor
and an expander. The transceiver contains a DSP (IC102) to
perform this operation. The transceiver compander can be
turned on or off using the FPU.
10. 150C DC/DC Converter Protect
IC402
F401
DC/DC
SB3
Converter
0.15A
150C