Kenwood NX-411 Service Manual page 18

NX-411
The SBC signal becomes High after the ASIC operates,
and IC204 (5A) and Q201 (SB2) are turned on. IC207 oper-
ates by turning on these AVR ICs and FET switches.
The 5UC signal becomes High when an option is in-
stalled on the universal connector. Then IC18 (50U) oper-
ates.
When the /SAVE signal becomes High, IC205 (50C) op-
erates. The output of IC205 is connected to two FET switch-
es (Q207, Q205). When the SBC signal becomes High,
IC207 (33C) operates. The FET switches are controlled by
the ASIC. Q207 (50T) is turned on in transmit mode. Q205
(50R) is turned on in receive mode.
When the VOL SW is turned off, the /PSW signal be-
comes Low. After detecting the /PSW signal, the ASIC
changes the SBC signal to Low. Then the power supplies
except IC210 (31BU) stop.
F201
IC205
/SAVE
AVR IC
/5TC
/5RC
Q201
SBC
SB2 SW
IC204
AVR IC
IC18
5UC
AVR IC
IC210
AVR IC
IC206
DC/DC
SBC
VoL SW
IC209
Detect
Fig. 8 Power supply circuit
18
CIRCUIT DESCRIPTION
+B
RF Final AMP
APC
50C
VCO
50T
Q207
TX circuit
50T SW
50R
Q205
RX circuit
50R SW
Backlight,
SB2
Key Light,
TX/Busy LED
5A
Option
–10V
IC105
LCD bias
DC/DC
50U
Universal
31BU
Q208
SRAM, RTC
31BU
33C
IC207
PLL, VCO
AVR IC
33M
IC203
ASIC, DSP I/O,
AVR IC
FLASH, LCD DRV
15M
IC202
ASIC, DSP core
DC/DC
33A
IC201
ASIC Analog,
AVR IC
Audio
SB1 /PSW
Q203
Lvl Conv
Q206 D213
AND OR
IC309
/BINT
Q204 ASIC
Lvl Conv
D212
OR
8. Signaling Circuit
8-1. Encode (QT/DQT/LTR/DTMF/MSK)
Each signaling data signal of QT, DQT, LTR, DTMF and
MSK is generated by the DSP circuit, superimposed on a
modulation signal and output from the DSP (IC304) and
ASIC (IC309). The modulation balance of the QT/DQT/LTR
signal is adjusted by the D/A converter (IC3) and the result-
ing signal is routed to the modulation input of the VCO and
PLL IC (IC503). Each deviation of the TX QT, DQT, LTR,
DTMF and MSK tone is adjusted by changing the output lev-
el of IC304 and the resulting signal is routed to the VCO and
PLL IC (IC503). 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/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 (IC304) to
perform this operation. The transceiver compander can be
turned on or off using the FPU.