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3 - 2
3-2 MAIN UNIT
The MAIN UNIT is the core of IC-7200.
• RF INPUT/OUTPUT
The RX signals from the RF UNIT are passed through the
LPF and D523, then applied to the 1st mixer.
The TX signal from the YGR AMP is passed through D524
and LPF, then output to RF UNIT via J7.
• RX IF CIRCUIT
Q502, Q503, Q504 and Q505 (these are junction FETs)
compose a quad-structured 1st mixer circuit, and provides
high enough intercept point. RX signals are mixed with
the 1st LO signals from the 1st LO AMP (Q501) to be
converted into the 64.455 MHz 1st IF signal. The 1st IF
signal is filtered by the roofing filter (FI541) to remove the
RX frequency signal and 1st LO signals, and amplified by
the 1st IF AMP (Q551).
The amplified 1st IF signal is applied to the 2nd mixer (D571)
to converted into the 455 kHz 2nd IF signal. A double
balanced mixer is adopted to the 2nd mixer and is used for
both TX and RX.
The 2nd IF signal is filtered by FI601 and amplified by
Q653, Q652, Q651, then applied to the 3rd mixer (IC671).
The 3rd mixer operated by switching SPDT switch using LO
signal, and commonly used in TX and RX. The converted
15.625 kHz 3rd IF signal is applied to the DSP section.
• RX AF CIRCUIT
The 3rd RX IF signal is demodulated, audio level-adjusted
and squelch-controlled in the DSP, then directly applied to
the AF AMP.
IC1091 is an exclusive AF AMP for driving internal speaker.
While a headphone is connected, IC1081 cuts the input line
of IC1091 off. For the headphone operation, an extra AF
output line connected to the FRONT UNIT is available.
• MICROPHONE AMP CIRCUIT
The MIC signals from the FRONT UNIT are amplified by
IC1031 and are applied to the DSP. The TX audio signals
(MIC signals) are processed completely in the DSP (MIC
gain adjust, compression, etc.) entirely, thus no analog
circuits are required in this stage.
• TX IF CIRCUIT
The 15.625 kHz TX IF signal from the DSP section is
converted into the 455 kHz TX IF signal by IC571, then
amplified by the IF AMP (Q611). The amplified signal is
filtered by FI601 to remove unwanted signals and amplified
by Q581, then converted into the 64.455 MHz TX IF signal
by D571, filtered by FI541 for unwanted signal removal. The
64.455 MHz signal is then amplified by Q521, and mixed
with the 1st LO signals from the 1st LO AMP (Q501) by
IC521 to converted into the TX frequency. The converted
signal is amplified by Q531 and applied to the YGR AMP.
BUFF
AM P
AM P
AMP
RX IF
AM P
AM P
LPF
LPF
LPF
BPF
XTAL
BPF
CERAMIC
AMP
BUFF
TXS
3rd LO
2nd LO
1st LO
3rd IF
15.625 kHz
2nd IF
455 kHz
64.455 MHz
1st IF
15kHz
FI541
D571
FI601
Q651
Q652
IC591
Q653
Q611
Q581
Q551
Q521
IC1601,IC1621
IC1701
RX
TX
From
RF UNIT
Q502—505
IC521
IC1021
Q531
IC671
TX IF
TX IF
TX IF
RX IF
RX IF
- IF CIRCUITS (RX AND TX) -
- AF CIRCUITS (RX AND TX) -
AF
MUT E
AF
AM P
LPF
LPF
LPF
AF
MUT E
MIC
AM P
AF
AM P
AFMS
SPS
MICROPHONE
CODEC
SRAM
128KB
DSP
FLASH
ROM
TS462
TS462
3rd IF
15.625 kHz
INT SP
IC1091
IC1081
IC1051
IC1591
IC1531
IC1551
IC1661
TS462
I C1701
I C1082
IC1031
TS462
PHONE
IC1071
JACK
EXT SP
JACK
IC1601,IC1621
Summary of Contents for IC-7200
Page 1: ...SERVICE MANUAL ADDENDUM CONTENTS PARTS LIST 1 BOARD LAYOUTS 19 VOLTAGE DIAGRAM 21 Jun 2009 ...
Page 33: ...Oct 2008 SERVICE MANUAL ADDENDUM CONTENTS BOARD LAYOUTS LOGIC AND MAIN UNITS 1 Nov 2008 ...
Page 38: ...Oct 2008 SERVICE MANUAL ADDENDUM CONTENTS BOARD LAYOUTS RF AND MAIN UNITS 1 Oct 2008 ...
Page 74: ...S 14513XZ C1 Oct 2008 HF 50MHz TRANSCEIVER ...
Page 135: ...1 1 32 Kamiminami Hirano ku Osaka 547 0003 Japan S 14513XZ C1 2008 Icom Inc ...