4-2
• DEMODULATOR AND RX AF CIRCUIT
A/D
From the 3rd RX IF circuit
BUFF
BUFF
AF
MUTE
To the [SP] jack
IC8201
IC3611
CODEC
IC3608
IC3602,IC3603
IC3008
IC3615
LPF
5
0
0
3
C
I
IC3003
AF
PA
DSP
36 KHz 3rd RX IF
Electronic
volume
RL3001
Speaker
SW
IC3011
DSP2-A UNIT
DSP1-A UNIT
• TX AF CIRCUIT
DSP1-A UNIT
To the modulation circuits
AMP
IC3004
IC3008
AF GAIN
ADJ
MIC
AMP
MIC
ALC
IC6005
DISPLAY-A
UNIT
• MODULATION CIRCUIT
IC8201
DSP
DSP2-A
UNIT
DSP1-A UNIT
BUFF
BUFF
To the 3rd
TX IF circuit
From the TX
AF circuits
IC3611
CODEC
IC3611
CODEC
IC3604
IC3607
IC3615
• 3RD TX IF CIRCUIT
IF
AMP
BPF
CERAMIC
IF
AMP
RXIF
FI1402
IC1403
3rd IF SW
Q1417
Q1416
IC1402
3rd TX LO signal
From the modulation
circuits
To the 2nd TX
IF circuits
D1415
D1417
D1419
D1421
455kHz 2nd TX IF
DEMODULATOR CIRCUIT (DSP1-A UNIT)
The 3rd RX IF signal from the 3rd RX IF circuits is passed
through the buffer (IC3602, IC3603), and then applied to the
A/D converter to be converted into digital audio signal.
The converted digital audio signal is applied to the DSP
(IC8201) on the DSP2-A UNIT, and demodulated and pro-
cessed.
The demodulated signal is applied to the CODEC (IC3611)
to be converted into analog AF signal. The AF signal is
passed through the buffer (IC3615), LPF (IC3003) and AF
mute SW (IC3005), and then applied to the electronic vol-
ume (IC3008), which adjusts the AF output signal in level.
The level-adjusted AF signal is amplified by the AF power
AMP (IC3011), and then output from the connected speak-
er, through the speaker SW (RL3001) and speaker connec-
tor (J3006).
4-2 TRANSMITTER CIRCUITS
TX AF CIRCUIT (DISPLAY-A and DSP1-A UNITS)
The audio signal from the microphone (MIC signal) is
applied to the DISPLAY-A UNIT, through the MICROPHONE
CONNECTOR (MIC UNIT; J6902), and then applied to the
MIC AMP with ALC circuit (IC6005). The amplified MIC sig-
nal is applied to the DSP1-A UNIT.
The MIC signal from the DISPLAY-A UNIT is amplified by
the AF AMP (IC3004), and then applied to the electronic
volume (IC3008), which adjust the MIC signal in level.
The level-adjusted MIC signal is applied to the modulation
circuits.
MODULATION CIRCUIT (DSP1-A UNIT)
The MIC signal from the TX AF circuits is applied to the
CODEC (IC3611), through the Balance-Unbalance convert-
er (IC3604 and IC3607), to be converted into digital audio
signal.
The converted digital audio signal is applied to the DSP
(IC8201) on the DSP2-A UNIT, and processed and modu-
lated.
The processed signal is applied to the DSP1-A UNIT again,
and converted into analog audio signal by the CODEC
(IC3611), and then applied to the 3rd TX IF circuits on the
MAIN-A UNIT, through the buffer (IC3615), as the 3rd TX IF
signal.
3RD TX IF CIRCUIT (MAIN-A UNIT)
The 3rd TX IF signal from the modulation circuits is applied
to the 3rd TX IF mixer (IC1402), through the 3rd IF SW
(IC1403), to be mixed with the 3rd TX LO signal, resulting in
the 455 kHz 2nd TX IF signal.
The 2nd TX IF signal is amplified by the 2nd TX IF AMP
(Q1417), passed through the 2nd TX IF filter (FI1402), and
then applied to another 2nd TX IF AMP (Q1416).
The amplified 2nd TX IF signal is applied to the 2nd TX IF
circuits.
