3 - 3
AM P
RL2302
PWR
AMP
IC2312
VCA
IC2331
IC2331
AF
AM P
IC2301
SP1
LPF
Q2361
Squelch gate
AF mute SW
From the demodulation circuits
INT. SP
CHASSIS
J7
PHO/AFO
[PHONES]
[EXT-SP]
• RX AF CIRCUITS
3-2 TRANSMITTER CIRCUITS
TX AF CIRCUITS (MAIN UNIT)
The audio signals from the microphone (MIC signals)
are applied to the MAIN UNIT via the MICROPHONE
CONNECTOR (MIC BOARD; J1), and applied to the Voltage
Controlled Amplifi er (VCA; IC2601).
The applied MIC signals are amplifi ed by internal MIC AMP,
and adjusted its level (=MIC gain) by internal VCA circuit.
The level-adjusted MIC signals are passed through the
MIC line selector (IC4101), and amplified by the AF AMP
(IC4205), then applied to the modulation circuits.
The signals from the external equipment connected to the
accessory socket [ACC1] on the rear panel, are directly
applied to the AF AMP (IC4205) via the MIC line selector
(IC4101).
RX AF CIRCUITS (MAIN UNIT)
The AF signals from the buffer amplifier are applied to
the AF AMP (IC2301) via the squelch gate (Q2361). The
amplified AF signals are applied to the Voltage Controlled
Amplifier (VCA; IC2231) to be adjusted its level (=audio
output level).
The level-adjusted AF signals are applied to the AF power
AMP (IC2312) via the LPF (Q2312).
The amplified MIC signals are applied to the modulation
circuits.
MODULATION CIRCUITS AND DSP (MAIN UNIT)
The MIC signals from the TX AF circuits are applied to the
Balance-Unbalance converter (Balun; IC4201, 4204), and
the converted MIC signals are applied to the A/D converter
(IC4301) to be converted into the digital signal.
The converted digital signal is applied to the DSP (IC5001)
and modulated and processed.
The modulated signal is converted into the analog signal by
the D/A converter (IC4301), and passed through the balun
(IC4401) to be converted into the 3rd TX IF signal.
The converted 3rd TX IF signal is applied to the 3rd TX IF
circuits.
The power-amplifi ed AF signals are passed through the AF
mute switch (RL2302), then applied to the internal speaker
or external speaker jack (J2302) on the rear panel or
headphone jack (JACK BORD J2) on the front panel.
IC4401
3rd TX IF circuits
3rd TX IF->
DSP
IC5001
IC4301
IC4101
MIC
AMP
IC2601
CP1
IC4201,
IC4204
VCA
MIC GAIN ADJ.
MIC LINE SELECT
MC 1
MIC_IN
AF
BALUN
BALUN
AM P
IC4205
IC4301
A/D
(CODEC)
D/A
(CODEC)
ACC(1)
MOD
MIC BOARD
MAIN UNIT
• TX AF AND MODULATION CIRCUITS