Icom IC-Q7A Service Manual

4-3-2 1ST VCO CIRCUIT (RF UNIT)
The
1st
VCO
circuit
contains
a
separate
V
VCO
(Q32,
D45)
and
U
VCO
(Q28,
Q30,
D54).
The
oscillated
signal
is
ampli-
fied
at
the
buffer
amplifiers
(IC4,
Q40),
and
is
then
applied
to
the
Tx/Rx
switching
circuit
(D23,
D28, 042,
043,
D44).
Then
the
Tx
and
Rx
signals
are
applied
to
the
pre-driver
(Q23:
for
VHF,
Q22:
for
UHF)
and
1st
mixer
(IC1)
respectively.
A
portion
of
the
RF
signal
from
buffer
amplifier
(IC4)
is
ampli-
fied
at
the
buffer
amplifier
(Q43),
and
is
then
fed
back
to
the
PLL
IC
(IC3
pin
19)
as
the
comparison
signal.
4-3-3 2ND LO VCO CIRCUIT (RF UNIT)
The
2nd
LO
VCO
circuit
generates
the
2nd
LO
frequencies,
and the signals are applied to the 2nd mixer circuit.
The
generated
signals
from
the
2nd
VCO
(Q6,
D17)
are
applied
to
the
2nd
mixer
(IC10,
pin
3),
then
mixed
with
the
1st
IF
signal.
An
oscillated
signal
from
the
2nd
VCO
passes
through
the
low-pass
filter
(C154,
C250
—
C252,
L69)
and
is
applied
to
the
PLL
IC
(IC3,
pin
2),
and
is
then
output
from
pin
8.
e 2nd LO VCO circuit
037, 053
Ripple
filter
АЗУ
to the 2nd mixer (IC10)
* PLL circuit
Loop
Q2, 045 | filter
4-4 POWER SUPPLY CIRCUITS
VOLTAGE LINE
LINE | DESCRIPTION
The voltage from the attached battery.
Common 13 V converted from BATT line by the
DC-DC convertors (IC10 and D3, D5, D15). The
output voltage is applied to the PLL circuit (RF
unit).
VHF
transmit
2V
controlled
by
the
+2.0
switch
VHT2V
|e
from
the
+2V
regulator
(Q21,
Q32)
using
VP
the "TXV" signal from CPU (IC11).
UHF transmit 2V controlled by the +2.0 switch
UHT2V
|
(028)
from
the
+2V
regulator
(021,
Q32)
using
the "TXU" signal from CPU (IC11).
язу
|
Receive
ЗУ
controlled
by
the
R3S
regulator
cir-
cuit
(Q4)
using
the
“RX”
signal
from
CPU
(IC11).
Common 3V converted by the +3S regulator cir-
43S
|сий
(Q3,
039)
using
the
“+3$С”
signal
from
CPU
E 1).
Common 3V controlled by the +3V regulator cir-
43V
|
сий
(Q6)
using
the
“РОМЕНС”
signal
from
CPU
E (IC11).
Transmit 3V controlled from +3V line by the 3V
regulator circuit (Q5).
to transmitter circuit
—
to 1st mixer circuit
>.
Programmable
9 Prescaler
13 [Phase
[detector
tothe FMIFIC 17 Programmable
Гу PSTB
Shift register 15 CLK
DATA
| divider
16 }
х1 Са

Icom IC-Q7A Specifications

General

Brand	Icom
Model	IC-Q7A
Category	Transceiver
Language	English