Kenwood NX-200 Service Manual page 18

NX-200(G)
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
5A CN710
Sub (GPS) unit (X58)
CN10
GPS module
IC4 31V
Buffer
AVR IC
V_BCKP
Lithium cell
Fig. 8 Power supply circuit
18
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, super-
posed on a modulation signal and output from IC108. The
modulation 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 adjusted by changing the output level of IC108 and
the resulting 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 decoded.
9. Compander Circuit
The term "compander" means compressor and expander.
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. GPS Circuit
The GPS information function can be used by setting it
through the FPU. When the GPS information function is
enabled, the AVR (IC4/GPS) is enabled by the OPT5, and is
supplied to the GPS circuit.
The GPS circuit block consists of a TX-RX unit and
a GPS unit (X58). The circuit from an antenna to LNA is on
a TX-RX unit. This output is connected to the GPS unit by
the coaxial cable.
The GPS signal of 1575.42MHz received with the an-
tenna (with GPS band) is passed by the HPF and BPF (L605/
TX-RX) and is amplifi ed by the LNA (IC881/TX-RX).
The GPS signal is processed by the GPS IC (IC1/GPS)
and input to the ASIC (IC108/CONT) through the UART port.
The ASIC (IC108/CONT) processes the GPS data (NMEA)
and sends the resulting information to the LCD.
The GPS IC operates in stand-alone. Operating voltage
is 3.1V. When the transceiver power is off, the GPS IC will
be backed up with the internal coin battery. When the battery
pack is removed, the GPS IC will be backed up for about
one day in a coin battery. But if the GPS IC has never had
the position fi xed, it will not be backed up.
When the GPS function is enabled, the consumption cur-
rent increases by about 70 mA.