Icom IC-3200A Service Manual page 12

2.
TX/RX
Switching
Circuit
When
the
PTT SWITCH
on
the
microphone
is
pushed,
pin
5
of
J1
becomes
LOW
and thecolfectorof
Q4 becomes
HIGH.
Q3
reverses
this
signal to
supply the transmit
mode
signal
to
the
SEND
port
on
the
CPU.
3.
TX
Control
Pin
13on IC3A
is
connected
to
the
MUTE
port
on
the
CPU
to
eliminate
unwanted
signals
from being transmitted.
If
an
out-of-barid
frequency
is
selected,
the output
level
from
ICS
A
Stays
LOW
to
mute
the transmit signal
when
the
PTT
SWITCH
on
the
microphone
is
pressed.
4.
Power
ON
Reset
Circuit
When
the transceiver
is
turned
ON,
a signal
from
IC4C
is
Supplied
to
IC3C and
the
main
matrix on the
LOGIC A
UNIT.
If
the
FUNCTION SWITCH
is
pressed
when
the transceiver
is
being switched
ON,
IC3 sends
a reset
signal
to
the
CPU.
5.
Scan
Stop
Circuit
When
the
SQL
Ssignal from
the
MAIN UNIT
is
HIGH,
it
turns
ONOBand
passes thesignal
to
the
SCAN STOP
port
on
the
CPU.
Also,
06
controls the
D13
receive
LED.
a.
Mic
UP/DOWN
Circuit
When
the
UP/DOWN
SWITCH
on
the
microphone
is
pressed, asignal
is
supplied
to
the
MIC CK
port
on
the
GPU.
When
the
UP SWITCH
is
pushed, the collector of ICS
becomes HIGH.
When
the
DOWN
SWITCH
is
pushed, the
collectorof
IC5
becomes LOW. The
CPU
receives
this
signal
from
the
U/D
port
on the
CPU
to
control the
microphone
scanning function
3-4-3
LOGIC
B
UNIT
1. Initial
Matrix
CircuUs
IC1,
the
BCD-To-Decimal Decoder on
the
LOGIC B
UNIT,
decodes
the
initial
matrix signal
generated by the following
diodes
on each
lC-3200 version:
(4)
Q5
-
A1
(Ax)
This matrix
sets
the
frequency
step
and the reference
frequency
of
the
PLL
circuit
on
BAND
B.
When
the
matrix (especially
Q5
—
At)
is
ON,
a reference
frequency
of
6.25kHz
is
selected;
when
Q5
At
is
OFF,
a
reference
frequency
of
5kHz
is
selected.
Q5 Ax
(REFERENCE
3
}
This matrix sets the
frequency
step
on
BAND
B.
(5)
Q6->^A2(OWA)
This matrix setstheoffset frequency
in
duplex
mode
on
BAND
A when
transceiver
power
is
turned
ON.
When
the matrix
Q6
A1
is
ON,
ani offset
frequency
of
600kHz
is
selected.
(6)
Q7
-A1(A4KOWB)
This matrix sets the offset
frequency
in
duplex
mode
on
BAND
B when
transceiver
power
is
turned
ON.
When
the matrix
Q7 A4
is
ON,
an
offset
frequency
of
5.0MHz
is
selected.
When
both
Q7
A1 and
Q7 A4
are
ON,
an
offset
frequency
of
7.6MHz
is
selected
for
the
IC-3200E
version.
(7)
09
A1
(VOICE
SYNTHESIZER ON/OFF}
This matrix setsthe
ON
or
OFF
condition forthe signals
of
the voice synthesizerunit,
When
the matrix
is
OFF. no
data signals
for
the
voice synthesizer are output.
When
the matrix
is
ON,
the data signals are output.
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Qo
Ax
(BAND
A/VHF}
This matrix sets the
frequency bandwidth
on
the
VHF
(BAND
AJ.
NOTE: The
value
of
x
will
vary with
each
transceiver
version.
{
2
}
01
Ax
(BAND
B/UHF)
This matrix sets the
frequency bandwidth on
the
UHF
(BAND
B).
IC-3200A
(VK)
(3)
Q4
-
A1
(AX>
(REFERENCE
A)
This matrix
sets
the
frequency step
and
reference
frequency of the
PLL
circuit
on
BAND
A.
When
the
matrix
fespecialiy
04
—
A1)
is
ON,
a reference
frequency
of
6.25kHz
is
selected;
when
Q4
—
A1
is
OFF,
a reference frequency
of
5kHz
is
selected.
IC-3200E
Q4
-
Ax
This matrix sets the frequency
step
on
BAND
A,
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