4·1·27 SQUELCH SWITCH CIRCUIT (MAIN UNIT)
The base
of
Q2
receives output voltage from
IC7(B)
via 027 when the noise squelch is activated,
or
output voltage from IC4(B) via 020 when the meter
squelch
is
activated.
Q2
switches
03.
Q6 turns
Q1
(the squelch switch)
ON
and OFF, and
Q1
switches AF
signals. The collector voltage
of
03
is applied
to
the base
of
Q4.
The, and the output
of
Q4
lights up
the
"SIG"
INDICATOR on the FREQUENCY DISPLAY.
4·1·28 VSC (Voice
Scanning
Control)
CIRCUIT
(MAIN UNIT)
This circuit sends the
VSC
signal
to
the LOGIC UNIT
when the IC·R7000 receives signals with AF signal
components.
Output from
Q1
is
fed
to
IC1{A).
An active low-pass
filter
consisting
of
IC1(A),
R7-R12,
and
C6-C10
blocks signals higher than 1 kHz to prevent
circuit
malfunctions. Output from
IC1(A)
is amplified by
IC1
(B).
02
detects AF signal components in the
output
of
IC1(B), and then the detected voltage
is
charged at
C15.
The voltage
of
C15
is
applied
to
comparator IC2(A). IC2(A) outputs
"HIGH"
output
to pin 7
only when receiving signals with AF signal
components.
Q5
and
Q7
control relay
RL
1 for the [RECORDER-
REMOTE] JACK.
RL
1 turns
ON
when the squelch
opens.
VSC
operation is given priority even when the
squelch opens. When the
VSC
function is activated,
the
MO signal form the LOGIC UNIT is applied to 07,
and
RL
1 turns OFF.
4·1·29 SCANNING CONTROL CIRCUIT (MAIN UNIT)
Output from the center detector circuit and the
MUTE
signal from the LOGIC UNIT is applied to the base
of
Q10.
010
turns OFF only when the CENT signal and
MUTE
signal
is
"LOW"
(the squelch opens when the
receiver
is
tuned
to
the center
frequen~y).
When
Q10
turns OFF, a STOP signal
is
sent
to
the LOGIC UNIT
via
R72
and
Q11,
and scanning stops.
Q11
switches the STOP signal OFF when the
[SQUELCH] CONTROL
is
turned fully counterclock-
wise.
4·1·30 METER CIRCUIT (MAIN UNIT)
(a) S·METER CIRCUIT
In
FM
(wide} mode, the METER receives $-meter
(SM)
signals via
D16
when receiving a strong signal,
or
SM
signals from IC4(A) via 015 when receiving a weak
signal.
In
FM
(narrow), SSB
or
AM
modes, the METER receives
SM
signals via
D18.
4-6
(b) CENTER METER CIRCUIT
CENT signal from the IF UNIT is inversion-amplified
at
IC2(B).
Output voltage from
IC2(B)
is applied
to
the
METER
as a center meter
(CM)
signal.
In
SSB
mode,
Q17
turns the center
(CENT)
signal
from
IC5
and the center meter
(CM)
signal from
IC2(B)
OFF.
4·1·31 AUDIO FREQUENCY (AF) AMPLIFIER CIRCUIT
(MAIN UNIT)
Output from
Q1
is
applied
to
IC3(B) (pin
1).
The
[AF
GAIN] CONTROL controls the voltage
of
IC3(B)
(pin
13)
to
vary the AF gain.
Output from
IC3(B)
is
amplified up
to
a sufficent AF
level by IC8
to
drive the speaker
SP1.
Output from
Q1
is also applied
to
buffer amplifier
IC3(A).
Output from
IC3(A)
is fed to the [RECORDER·
REMOTE] JACK.
Q18
amplifies SPK signals from the optional IC-EX310
VOICE SYNTHESIZER UNIT,
and signals from
Q18
are applied
to
IC3(B).
4·2 POWER SUPPLY CIRCUITS
4·2·1 REG CIRCUIT (REG UNIT)
The
AC
power source from the AC
POWER
SOCKET
is fed to
T1.
Voltage from
T1
is
rectified by 01, next
it
is then fed
to
the stabilization circuit consising
of
Q1, Q2,
and
Q3,
and then
it
is supplied
to
other circuits.
4·2·2 DC·DC CONVERTER CIRCUIT
(DC·DC UNIT)
This circuit converts 13.8V
DC
from the
REG
UNIT
to
-7V,
-12V
and
+24V
DC
voltage. This
circuit
consists
of
a oscillation circuit, a voltage step up/
down transformer, and three
regulator circuits.
(MAIN UNIT)
RL2
is a power ON/OFF switch operated by the
optional
RC-12
WIRELESS REMOTE CONTROLLER.
The power control
(POC)
signal from the
RC-12
switches
Q13
and
013
switches
RL
12.
IC6
is
a voltage regulator
that
supplies a stabilized
9V
to
the MAIN UNIT, IF UNIT and
RF
UNIT.
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