Icom IC-F1010 Service Manual

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CTCSS
AND DTCS
A
portion
of the
AF
signals from
the AF
amplifier
(lC2) pass
through the low-pass filters
(lC4alb)
and are
then amplified
at
the tone
amplifier
(lC28a).
The
signals
are applied
to the
CTCSS decoder inside
the CPU
(1C20
pin
98) to
control the
UAMUT"
and
"SP"
ports.
When
the DTCS system is in
use,
the amplified
signals are
converted into
digital signals
at lC28b,
then apptied
to the
DTCS
decoder inside
the CPU
(1C20
pin
23).
The
"LFSW"
port
(1C20 pin
62)
controls
the LPF
(lO4a)
characteristics
to shift the
cut-off frequency
for
CTCSS
and
DTCS separately.
+2 TRANSMITTER
CIRCUITS
4.2.1
MICROPHONE
AMPLIFIER
CIRCUIT
The
microphone
amplifier
circuit
amplifies
the audio signals
with +6
dB/octave
pre-emphasis
characteristies from
the
microphone
to a level needed
for
the
modulation
circuit.
AF
signals
(MlC)
from
the FRONT
unit via
J5
(pin
't0)
are
applied
to the audio
switch
(1C25).
While
transmitting,
the
MCON
signalfrom
the CPU is
"High"
and the AF
signals
pass
to
the
microphone
amplifier circuit.
The
AF
signals from lC25
are
applied
to the microphone
amplifier lC
(1C22)
via
the
preamplifier
(lC21b).
The
amptified
signals
are applied to
the
limiter
amplifier in 1C22,
The
entered
signals
(1C22
pin
16)
are
pre-emphasized
with
+6
dB/octave
at a limiter
amplifier,
then
passed
throulh
a
splutter filter. The
output
signals from
pin
8
pass
through
the
level
controller
(lC5 pins
4, 3)
and are
then applied
to the
modulation
circuit
(D23,
D46) via
Q52.
4-2.2 MODULATION
CIRCUIT
The modulation
circuit
modulates
the VCO
oscillating
signal
(RF
signal) using
the microphone
AF
signals.
o
MICROPHONE
AMPLIFIER
CIRCUIT
The AF
signals from
Q52
change
the reactance
of D23
and
D46
to modulate
the
oscillated
signal
at the
Tx VCO
circuit
(O23).
The modulated
signal is
amptified
at the buffer
amplifiers
(Q19,
Q20)
and is
then apptied
to
the drive
amptifier
circuit.
The
CTCSS/DTCS
signals from
lC5
(pin
2)
are arnptified
at
lC21a,
and are
applied
to the reference
oscillator
circuit
(e34,
X3,
014 for
tC-F1010
0r X3; tC29
for
tC-F1020)
to modutate
the
oscillated
signal.
4.2-3
DRIVE/POWER
AMPLIFIER
CIRCUITS
The
signal from
the
buffer
amplifier
(Q20)
is
passed
through
the Tx/Rx
switching
circuit
(D17),
and
amplified
by
the driver
(O15-Q17)
and the
power
modute
(tC1
1
)
to obtain
25 W
(lC-F1010)
or 45 W
(lC-F1020)
of RF
power.
The
amplified
signal
is
passed
through
the antenna
switching
circuit
(D4),
low-pass
filter
and
APC
detector,
and is
then
applied
to the
antenna
connector.
The
collector
voltages
for
drivers
(Q15,
Q16
for
lC-F1010;
Q16 only for
lC-F1020)
come from
the MTSV
regutator
(e38).
The
transmit
mute
switch
(Q39)
controls
the regulator
when
transmit
mute is
necessary.
4-2-4
APC
C|RCU|T
The
APC
circuit
protects
the
power
module
(1C11)
from
a
mismatched
output load
and
stabilizes
the
output
power.
The
APC
detector
circuit
detects
forward
signals
and reflection
signals
at D3
and D1
respectively.
The
combined
voltage
is
at
a minimum
level
when
the antenna
impedance
is matched
at
50
O
and is
increased
when it is
mismatched.
The
detected
voltage
is
applied
to the inverse
amplifier
(lC10b
pin
5),
and
the
power
setting voltage
(PSET)
is
apptied
to
the
other
input
(lC10b
pin
6) via
the
amplifier
(tC10a).
When
antenna
impedance
is mismatched,
the detected
voltage
exceeds
the
power
setting voltage.
Then
the
output voltage
of
the inverse
amplifier
(lC10b
pin
7)
controls
the input
current
of
the
power
module
(lC1
1)
(and
Q15
for
lC-F
j
020)
to decrease
the
output
power.
.
APC
CIRCUIT
ral
is
mls,
hryel
r.dse
o
the
tWlz
I
pin
tsols
IAF
4-2

Icom IC-F1010 Specifications

General

Brand	Icom
Model	IC-F1010
Category	Radio
Language	English