Icom IC-Q7A User manual

О
ІСОМ
SERVICE
MANUAL
VHF/UHF FM TRANSCEIVER
IC-Q7A
IC-Q7E
Icom Inc.

INTRODUCTION
This
service
manual
describes
the
latest
service
information
for
the
IC-Q7A/IC-Q7E
at
the
time
of publication.
MODEL VER SION SYMBOL
|
eee
=
ლოძის
To upgrade quality, all electrical or mechanical parts and
internal circuits are subject to change without notice or oblig-
ation.
DANGER
NEVER connect the transceiver to an AC outlet or to a DC
power
supply
that
uses
more
than
3.5
V.
Such
a
connection
could cause a fire hazard and/or electric.
DO
NOT
expose
the
transceiver
to
rain,
snow
or
any
liquids.
DO
NOT
reverse
the
polarities
of
the
power
supply
when
con-
necting
the
transceiver.
DO
NOT
apply
an
RF
signal
of
more
than
20
dBm
(100mW)
to
the
antenna
connector.
This
could
damage
the
trans-
ceiver's
front end.
ORDERING PARTS
Be
sure
to
include
the
following
four
points
when
ordering
replacement
parts:
1. 10-digit order numbers
2. Component part number and name
3.
Equipment
model
name
and
unit
name
4.
Quantity
required
SAMPLE ORDER:
8930046580 LCD Contact IC-Q7 LOGIC UNIT 5 pieces
8810009560 Screw PH BO М2х6 ZK .1C-Q7 Chassis 10 pieces.
Addresses are provided on the inside back cover for your
convenience.
REPAIR NOTES
Make sure a problem is internal before disassembling the transceiver.
DO NOT open the transceiver until the transceiver is disconnected from its power source.
DO NOT force any of the variable components. Turn them slowly and smoothly.
DO
NOT
short
any
circuits
or
electronic
parts.
An
insulated
turning
tool
MUST
be
used
for
all
adjustments.
DO NOT keep power ON for a long time when the transceiver is defective.
DO NOT transmit power into a signal generator or a sweep generator.
ALWAYS
connect
a
30
dB
to
40
dB
attenuator
between
the
transceiver
and
a
deviation
meter
or
spectrum
analyzer
when
using
such test
equipment.
READ the instructions of test equipment thoroughly before connecting equipment to the transceiver.
oo ROLL Mo
e

SECTION
SECTION
SECTION
SECTION
SECTION
SECTION
SECTION
SECTION
SECTION
SECTION
SECTION
4-1
4-2
4-8
4-4
4-5
5-1
5-2
5-3
5-4
9-1
9-2
10
11
11-1
11-2
TABLE OF CONTENTS
SPECIFICATIONS
INSIDE VIEWS
DISASSEMBLY INSTRUCTIONS
CIRCUIT DESCRIPTION
RECEIVER CIRCUITS и. cee loas RR E a
TRANSMITTER CIRCUITS .................................
РЦЕСІНСІЛТӘ; армарзанаа арағын а СЫНЫН Иа
POWER SUPPLY CIRCUITS ................................
PORT ALLOCATIONS .....................................
ADJUSTMENT PROCEDURES
PREPARATION „х ee REC I Rege ао ЛОН
PLL, ADJUSTMENT .... аа л санч ით დაბ A თაბი Td
RECEIVER ADJUSTMENT .................................
TRANSMITTER ADJUSTMENT ..............................
PARTS LIST
MECHANICAL PARTS AND DISASSEMBLY
CABINET PARIS: „2:2 22:5 Бу uve ка көле терен ез
SEMI-CONDUCTOR INFORMATION
BOARD LAYOUTS
LOGIC UNIT: лор ое Бйр» кузи а кары eat aap aaa
REUNIT fics seca ean alone eed be 8 а Rude Sese გრ
BLOCK DIAGRAM
VOLTAGE DIAGRAM
LOGIC UNIT а ke Ege qa Rey жа MRE aie eie ace ЕР
HISUNIT. 5а ы Dose Ба obs ұлық ы Es AL ES etos As

SECTION 1
SPECIFICATIONS
@ GENERAL
* Frequency range
U.S.A.
Version | Transmit (MHz)
144 — 148
440 — 450
Receive (MHz)
30.0 — 823.995
849.0 — 868.995
894.0 — 1309.995*
Europe
144 – 146
430 — 440
30.0 — 1309.995*
Italy, Asia
TWN
136 – 174*
430 — 440
144 – 148
430 — 440
30.0 – 1309.995*
30.0 — 1309.995”
144 — 148
430 — 450
30.0 - 1309.995*
*' Specifications guaranteed 144 — 148 MHz
* Specifications guaranteed 30 — 1300 MHz
* Mode
* No. of memory channels
* Frequency stability
* Tuning steps
* Anntena Impedance
* Power supply requirement :
* Polarity
* Frequency resolution
* Current drain (at 3.0 V DC) :
Receive
Transmit
* Usable temperature range :
* Dimensions
(projections not included)
* Weight
(with antenna and battely)
* MIC/SP connector
8 TRANSMITTER
* Output power (at 3.0 V DC) :
* Modulation system
* Max. freq. deviation
* Spurious Emissions
: ЕЗ (FM)
: 200 channels
: x6 ppm max. (-10'C to +60°C)
: 5, 6.25, 10, 12.5, 15, 20, 25,
30, 50, and 100 kHz
:50 Q
2 x AA(R6) Ni-Cd
or alkaline cell
: Negative ground
: 5 kHz, 6 kHz
Standby 95 mA (typical)
Max audio 170тАҰА (typical)
Power saved 38 mA (typical)
VHF 440 mA (typical)
UHF 380 mA (typical)
—10'C to +60°C
-14°F to +140°F
: 58(W) x 86(H) x 27(D) mm
9962(VV) x 838(Н) x 1V6(D) in
: 170 (g); 6 oz
: 4-conductor 3.5(d) mm (18°);
2 kQ/8 Q
VHF 350 mW
UHF 300 mW
: Variable reactance modulation
: x5 kHz
: less than -40 dB
Ш RECEIVER
* Receiver system : Tripple super heterodyne
* Intermediate frequency — : 1st 266.7 MHz
2nd 19.65 MHz
3rd 450 kHz
* Sensitivity"
032
118.0 — 136.0
(except spurious points; typical values)
247.0 – 330.0
330.0 — 380.0
*FM and WFM are measured at 12 dB SINAD; AM is measured
at 10 dB S/N.
* Squelch sensitivity :
less than 0.18 pV
144 – 148 MHz
430 - 450 MHz less than 0.22 uV
* Selectivity :
FM, AM more than 15 КН2/-6 dB
less than 30 КН2/-60 dB
WFM more than 150 kHz/—6 dB
: 100 mW typical at 10 % dis-
tortion with an 8 Q load
* Audio output power
All stated specifications are subject to change without notice or obligation.
1-1

SECTION2
INSIDE
VIEWS
è LOGIC UNIT
AF power amplifier
(IC15: TA31056F)
AF mute switch
(Q37: 28J144)
+3.2 regurater -
(IC4: S-81332HG)
AF filter
(030: XP6501)
+3 гедигаіег ——— — — Wai |
(IC3:
ХС62РРЗОО2МН)
1
* RF UNIT
TOP VIEW BOTTOM VIEW
end mixer
(IC10: uPC2757T-E3)
1st mixer
(IC1: uPC2757T-E3)
IF amplifier
(Q5: 25C5231)
- FM IF IC
(IC2: ТАЗ1136ЕМ)
Tx amplifier
Tx
amplifier
хаг
сїгсий
circuit
УСО circuit
PLL circuit
PLL IC
(IC3: wPD3140GS)
PLL reference oscillator
(X1: CR-583 19.200MHz)

SECTION 3 DISASSEMBLY INSTRUCTIONS
* REMOVING THE REAR PANEL е REMOVING THE LOGIC UNIT
(D Unscrew 2 screws, (А). (D Unscrew 2 screws, (6),
(2 Remove the rear panel in the direction of the arrow. (2) Unsolder 2 points, CI, and then remove the LOGIC unit.
Rear panel
e REMOVING THE RF UNIT
(D Unscrew 1 screw, (8),
(2 Remove 1 knob, (O.
Unscrew 2 nuts, © апа ©.
(3) Unsolder 5 points, ©, and then remove the RF unit.

SECTION 4
CIRCUIT DESCRIPTION
4-1 RECEIVER CIRCUITS
4-1-1 ANTENNA SWITCHING CIRCUIT (RF UNIT)
The RF signals from the antenna connector pass through the
antenna switching circuit (D3, D6, D9). The passed signals
are then applied to either Duplexer or RX band switching cir-
cuit.
4-1-2 DUPLEXER CIRCUIT (RF UNIT)
The transceiver has a duplexer (low-pass and bandpass fil-
ters) on the frist stage from the antenna switcing diode to
separate the signals into VHF and UHF signals.
* RF signals below 175.0 MHz
The RF signals below 175.0 MHz are passed through the
low-pass filter (L57-L59, С8-С11, C67) and are applied to
the VHF RF circuit.
• RF signals 330.0 МН2--469.995 MHz
The 330 MHz-469.995 MHz RF signals are passed through
the bandpass filter (13-15, C21-C24, C218) and are applied
to the UHF RF circuit.
4-1-3 VHF/UHF RF CIRCUIT (RF UNIT)
The VHF/UHF RF circuit amplifies the received signals with-
in the range of frequency coverage and filters out-of-band
signals.
(1) VHF RF CIRCUIT
The filtered signals from the low-pass filter circuit are ampli-
fied at the VHF RF amplifier (Q14) through the Tx/Rx swich-
ing diode (D15), and are then passed through the two stages
of tunable bandpass filters (D1, D2, L28, L1). The filtered sig-
nals are applied to the 1st mixer circuit (IC1, pin 1) via the
band switching diode (D25).
(2) UHF RF CIRCUIT
The filtered signals from the bandpass filter circuit are ampli-
fied at the UHF RF amplifier (Q35) via the Tx/Rx switching
diode (D27) and are passed through the two stage of tunable
bandpass filters (D4, D5, L61, L60). The filtered signals are
applied to the 1st mixer circuit via the band switching diode
(D29). The filtered signals are applied to the 1st mixer circuit
(IC1, pin 1).
The tunable bandpass filters employ varactor diodes (D1, D2,
D4, D5) to tune the center frequency of the RF passband for
wide bandwidth receiving and good image response rejec-
tion. These diodes are controlled by the CPU (LOGIC unit;
IC11, pin 9).
4-1-4 RX BAND SWITCHING CIRCUIT (RF UNIT)
The signals from the antenna connector pass through the
antenna switching circuit (D6, D9). The signals are then
applied to the RX RF circuit via RX the band switching circuit
(D11, D13, D31) which suppress out-of-band signals.
4-1-5 RX RF CIRCUIT (RF UNIT)
The RX RF circuit amplifies the received signals within the
range of frequency coverage and filters out-of-band signals.
(1) 470.0 MHz-1026.995 MHz signals
RF signals (470 MHz-1026.995 MHz) from a band switching
circuit (011) pass through a bandpass filter (L7, L8, L42,
C32, C33, C35-C39, C145) and are amplified at an RF
amplifier (Q24). The amplified signals are then applied to the
1st mixer circuit (IC1) through the band switching diode
(D32).
(2) 30.0 MHz-117.995 MHz, 175 MHz-329.995 MHz
The 30.0 MHz – 117.995 MHz, 175 MHz – 329.995 MHz sig-
nals pass through a low-pass filter (L9, L10, C40-C43) via
the band switching diode (D13), and are then amplified at the
RF amplifier (Q36). The amplified signals are applied to the
1st mixer circuit (IC1) via the band switching diode (D34).
(3) 1027.0 MHz-1309.995 MHz
The 1027.0 MHz-1309.995 MHz signals pass through a
bandpass filter (L11, L12, L43, C4, C5, C45 – C51) via the
band switching diode (D13), and are then amplified at the RF
amplifier (Q36). The amplified signals are applied to the 1st
mixer circuit (IC1) via the band switching diode (D36).
4-1-6 1ST MIXER CIRCUIT (RF UNIT)
The 1st mixer circuit converts the received RF signals to a
fixed frequency of the 1st IF signal with a PLL output fre-
quency. By changing the PLL frequency, only the desired fre-
quency will pass through the bandpass filter at the next stage
of the 1st mixer.
The filtered RF signals are mixed with 1st LO signals at the
1st mixer (IC1) to produce a 266.7 MHz 1st IF signal. The 1st
IF signal is output from pin 6, and passed through the band-
pass filter (ҒІ1) to suppress unwanted harmonic compo-
nents. The filtered 1st IF signal is applied to the 2nd mixer
circuit.
The 1st LO signals are generated at the V VCO (Q32, D45)
or U VCO (Q28, Q30, D54) circuit (according to the receiving
frequency), and are applied to the 1st mixer (IC1, pin 3)
directly or passing through the doubler circuit (Q31) after
being amplified at the buffer amplifier (IC4, Q40).

4-1-7 1ST IF AND 2ND MIXER CIRCUITS (RF UNIT)
The 2nd mixer circuit converts the 1st IF signal to a 2nd IF
signal.
The filtered 266.7 MHz 1st IF signal from the bandpass filter
(ҒІ1) is mixed with the 2nd LO signal at the 2nd mixer (ІС10)
to produce a 19.65 MHz 2nd IF signal. The 2nd IF signal
passes through (except WFM mode) or bypasses (WFM
mode) the bandpass filter (FI3), and is then amplified at the
buffer amplifier (Q5). The amplified signal is applied to the
demodulator circuit. |
4-1-8 DEMODULATOR CIRCUITS (RF UNIT)
The demodulator circuit converts the 2nd IF signal into AF
signals.
The 19.65 MHz 2nd IF signal from the buffer amplifier (Q5) is
applied to the 3rd mixer section of the FM IF IC (IC2, pin 16),
and is then mixed with the 3rd LO signal for conversion into
a 450 kHz 3rd IF signal.
IC2 contains the 3rd mixer, limiter amplifier, quadrature
detector and S-meter detector, etc. A frequency from the PLL
reference oscillator is used for the 3rd LO signal (19.20
MHz).
(1) FM mode
The 3rd IF signal is output from FM IF IC (IC2, pin 3) and
passes through the ceramic bandpass filter (F12). The filtered
signal is fed back and amplified at the limiter amplifier section
(pin 5), then demodulated into AF signals at the quadrature
detector section (pins 10, 11) and detector coil (L21). The
demodulated AF signals are output from pin 9 and are
applied to the AF circuit (LOGIC unit).
(2) WFM mode
The 3rd IF signal from the 3rd mixer bypasses the ceramic fil-
ter (Fl2) and fed back to the limiter amplifier section (pin 5).
е 2nd IF AND DEMODULATOR CIRCUITS
R56
AF signal 'WFMS" 7095
The amplified signal is demodulated at the quadrature detec-
tor section (pins 10, 11) and detector coil (L21). The AF sig-
nals are output from pin 9 and are applied to the AF circuit
(LOGIC unit).
By connecting R55 to R54 in parallel, the output characteris-
tics of pin 12, "RSSI", change gradually. Therefore, the FM IF
IC can detect WFM components.
(3) AM mode
The filtered 3rd IF signal from the bandpass filter (Fl2) is
amplified at the 3rd IF amplifier (Q1). The amplified IF signal
is applied to the AM detector circuit (Q4) to convert into AF
signals, and the signals are applied to the AF circuit (LOGIC
unit).
4-1-9 AF AMPLIFIER CIRCUIT (LOGIC UNIT)
The AF amplifier circuit amplifies the demodulated AF sig-
nals to drive a speaker.
While in FM mode, AF signals from the demodulator circuit
(RF unit) are passed through the de-emphasis (R118, C66,
C68) and bandpass filter (Q30) and are then applied to the
pre-amplifier (Q31).
While in AM mode, AF signals are pass through the band-
pass filter (Q30) and are then applied to the pre-amplifier
(Q31).
While in WFM mode, AF signals are applied to the pre-ampli-
fier (Q31) directly.
The pre-amplified AF signals pass through the AF mute
switch (Q37), and are then applied to the electronic volume
control circuit (IC14, pin 6). The level controlled AF signals
are output from pin 7 and are applied to the AF power ampli-
fier (IC15, pin 1) via the buffer amplifier (Q36). The power
amplified AF signals are applied to the internal speaker via
the [EXT SP] jack.
3rd IF filter
50 kH
Х1
19.2 MHz
IC2 TA31136F
2nd IF (19.65 MHz)
from Q5
"SDET" signal to the IC11 (Logic unit)
"RSSI" signal to the CPU
O WFM pin 7 (Logic unit)
Q41 16242

The electronic volume control circuit controls AF gain, there-
fore, the AF output level is according to the [VOL] setting and
also the squelch conditions.
4-1-10 SQUELCH CIRCUIT(LOGIC AND RF UNITS)
* NOISE SQUELCH
The noise squelch circuit cuts out AF signals when no RF
signals are received. By detecting noise components in the
AF signals, the squelch circuit switches the AF mute switch.
A portion of the AF signals from the FM IF IC (IC2, pin 9) are
applied to the active filter section (IC2, pin 8). The active fil-
ter section amplifies and filters noise components. The fil-
tered signals are applied to the noise detector section and
output from IC2 (pin 13) as the “SDET” signal.
The “SDET” signal from IC2 (pin 13) passes through the
noise detector (LOGIC unit; IC1), and is then applied to the
CPU (LOGIC unit; IC11, pin 12) via "SQL" line. The CPU ana-
lyzes the noise condition and outputs the “AMUTE” signal to
AF mute switch (Q37).
Even when the squelch is closed, the AF mute switch (Q37)
opens at the moment of emitting beep tones.
* TONE SQUELCH
The tone squelch circuit detects AF signals and opens the
squelch only when receiving a signal containing a matching
subaudible tone (CTCSS). When tone squelch is in use, and
a signal with a mismatched or no subaudible tone is received,
the tone squelch circuit mutes the AF signals even when
noise squelch is open.
A portion of the AF signals from the FM IF IC (IC2, pin 9)
passes through the low-pass filter (LOGIC unit; IC9) to
remove AF (voice) signals and is applied to the CTCSS
decoder inside the CPU (LOGIC unit; IC11, pin 8) via the
“АТОМЕ” line to control the AF mute switch.
4-2 TRANSMITTER CIRCUITS
4-2-1 MICROPHON AMPLIFIER CIRCUIIT
(LOGIC UNIT)
The microphone amplifier circuit amplifies the audio signals
from the microphone, within +6 dB/octave pre-emphasis
characteristics (300 Hz—3 kHz), to a level needed for the
modulation circuit. The microphone amplifier circuit is used
for both the VHF and UHF bands.
The AF signals from the microphone are amplified at the
microphone amplifier (Q12) and the limiter amplifier (Q2)
which has a negative feedback circuit for +6 dB/octave pre-
emphasis.
The amplified signals are applied to the low-pass filter (Q7)
to filler out RF components and are then applied to the RF
unit as the "MOD" signal.
4-2-2 MODULATION CIRCUIT (RF UNIT)
The modulation circuit modulates the VCO oscillating signal
(RF signal) using the microphone AF signals
e VVCO
The applied signals from the limiter amplifier changes the
reactance of D45 to modulate the oscillated signal at the
VVCO circuit (Q32). The modulated signal is amplified at the
buffer amplifiers (IC4, Q40) and is then applied to the drive
amplifier circuit for VHF band.
* UVCO
The applied signals from the limiter amplifier changes the
reactance of D54 to modulate the oscillated signal at the
UVCO circuit (Q28, Q30). The modulated signal is amplified
at the buffer amplifiers (IC4, Q40) and is then applied to the
drive amplifier circuit for UHF band.
4-2-3 DRIVE/POWER AMPLIFIER CIRCUITS
(RF UNIT)
The amplifier circuit amplifies the VCO oscillating signal to
the output power level.
* VHF PA
The signal from the buffer amplifiers (IC4, Q40) is passed
through the Tx/Rx switch (023), and is amplified at the driver
amplifiers (023, 013) and the power amplifiers (09-012) to
obtain 350 mW of RF power.
The amplified signal is passed through the antenna switching
circuit (D16) and low-pass filter, and is then applied to the
antenna connector.
* UHF PA
The amplified signal from IC4, Q40 passes through the Tx/Rx
switch (D28), and is amplified to 300 mW of RF power at the
driver amplifiers (Q22, Q21) and the power amplifiers
(Q17-Q20).
The signal is applied to the antenna connector via the anten-
na switching circuit (D40).
4-3 PLL CIRCUITS
4-3-1 PLL CIRCUIT (RF UNIT)
A PLL circuit provides stable oscillation of the transmit fre-
quency and the receive 1st/2nd LO frequencies. The PLL cir-
cuit compares the phase of the divided VCO frequency to the
reference frequency. The PLL output frequency is controlled
by the divided ratio (N-data) of a programmable divider.
An oscillated signal from the 1st VCO via the buffer amplifiers
(IC4, 043) is applied to the PLL IC (ІСЗ, pin 19) and is
prescaled in the PLL IC based on the divided ratio (N-data).
The reference signal is generated at the reference oscillator
(X1) and is also applied to the PLL IC (pin 16). The PLL IC
detects the out-of-step phase using the reference frequency
and outputs it from pin 13. The output signal is passed
through the loop filter (Q2, Q45) and is then applied to the
VCO circuit as the lock voltage.

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