Icom IC706MKIIG User Manual
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Page 1
SERVICE
MANUAL
HF/VHF/UHF ALL MODE TRANSCEIVER
i706MK™G
INTRODUCTION
DANGER
This service manual describes the latest service information
for the IC-706MKIIG HF/VHF/UHF ALL MODE TRANSCEIVER at the time of publication.
VERSION NO.
#02, #12
#03, #13
#04, #14
#05, #15
#08, #18
VERSION
Europe
France
Spain
U.S.A.
Other
SYMBOL
EUR
FRA
ESP
USA
OTH
To upgrade quality, any electrical or mechanical parts and
internal circuits are subject to change without notice or
obligation.
NEVER connect the transceiver to an AC outlet or to a DC
power supply that uses more than 16 V. This will ruin the
transceiver.
DO NOT expose the transceiver to rain, snow or any liquids.
DO NOTreverse the polarities of the power supply when con-
necting the transceiver.
DO NOT apply an RF signal of more than 20 dBm (100 mW)
to the antenna connector. This could damage the transceiver’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>
1110004080 S.IC µPC2709T IC-706MKIIG MAIN UNIT 05 pieces
8810009020 Screw FH M2.6 x 5 ZK IC-706MKIIG Top cover 10 pieces
Addresses are provided on the inside back cover for your
convenience.
REPAIR NOTES
1. Make sure a problem is internal before disassembling the
transceiver.
2. DO NOT open the transceiver until the transceiver is
disconnected from its power source.
3. DO NOT force any of the variable components. Turn
them slowly and smoothly.
4. DO NOT short any circuits or electronic par ts. An insu-
lated tuning tool MUST be used for all adjustments.
5. DO NOT keep power ON for a long time when the trans-
ceiver is defective.
6. DO NOT transmit power into a signal generator or a
sweep generator.
7. ALWAYS connect a 50 dB to 60 dB attenuator between
the transceiver and a deviation meter or spectrum analyzer when using such test equipment.
8. READ the instructions of test equipment thoroughly
before connecting equipment to the transceiver.
TABLE OF CONTENTS
SECTION 1 SPECIFICATIONS
SECTION 2 INSIDE VIEWS
SECTION 3 CIRCUIT DESCRIPTION
3 - 1 RECEIVER CIRCUITS................................................................................................................................ 3 - 1
3 - 2 TRANSMITTER CIRCUITS ......................................................................................................................... 3 - 4
3 - 3 PLL CIRCUITS............................................................................................................................................ 3 - 6
3 - 4 LOGIC CIRCUITS....................................................................................................................................... 3 - 8
SECTION 4 ADJUSTMENT PROCEDURES
4 - 1 PREPARATION BEFORE SERVICING ...................................................................................................... 4 - 1
4 - 2 PLL ADJUSTMENTS................................................................................................................................... 4 - 2
4 - 3 TRANSMITTER ADJUSTMENTS............................................................................................................... 4 - 2
4 - 4 RECEIVER ADJUSTMENTS....................................................................................................................... 4 - 8
4 - 5 SET MODE ADJUSTMENT....................................................................................................................... 4 - 10
SECTION 5 PARTS LIST
SECTION 6 MECHANICAL PARTS AND DISASSEMBL Y
SECTION 7 SEMI-CONDUCTOR INFORMATION
SECTION 8 BOARD LAYOUTS
8 - 1 DISPLAY BOARD........................................................................................................................................ 8 - 1
8 - 2 MAIN BOARD.............................................................................................................................................. 8 - 3
8 - 3 HPF AND DRIVER BOARD........................................................................................................................ 8 - 5
8 - 4 PAUNIT....................................................................................................................................................... 8 - 7
8 - 5 PLL UNIT..................................................................................................................................................... 8 - 9
8 - 6 FILTER BOARD......................................................................................................................................... 8 - 11
SECTION 9 BLOCK DIAGRAM
SECTION 10 VOLTAGE DIAGRAM
■ GENERAL
• Frequency coverage :
Receive 0.030 – 200.000 MHz*
430.000 – 470.000 MHz*
Transmit 1.800 – 1.999 MHz*
3.500 – 3.999 MHz*
7.000 – 7.300 MHz*
10.100 – 10.150 MHz
14.000 – 14.350 MHz
18.068 – 18.168 MHz
21.000 – 21.450 MHz
24.890 – 24.990 MHz
28.000 – 29.700 MHz
50.000 – 54.000 MHz*
144.000 – 148.000 MHz*
430.000 – 450.000 MHz*
*Depending on version.
• Mode : USB, LSB, CW, RTTY(FSK), AM, FM,
WFM (WFM is for receiver only)
• Number of memory ch. : 107 (99 regular, 6 scan edges,1 call)
• Antenna connector : SO-239 ✕ 2
(for HF/50 MHz and 144/440 MHz)/50 Ω
• Power supply requirement : 13.8 V DC ±15% (negative ground)
• Frequency stability : Less than ± 7 ppm from 1 min. to 60
min. after power ON. After that, rate of
stability less than ±1 ppm/hr. at +25˚C
(+77˚F). Temperature fluctuations 0˚C
to +50˚C (+32˚F to +122˚F) less than
± 5 ppm.
• Current consumption :
Transmit max. power 20 A
Receive standby 1.8 A
max. audio 2.0 A
• Usable temperature range : –10˚C to +60˚C (+14˚F to +140˚F)
• Dimensions : 167(W)
✕ 58(H) ✕ 200(D) mm
(projections not included) 69⁄16(W) ✕ 29⁄32(H) ✕ 77⁄8(D) inch
• Weight : 2.45 kg (5 lb 6 oz)
• CI-V connector : 2-conductor 3.5 (d) mm (
1
/8")/8 Ω
• ACC connector : 13-pin
■ TRANSMITTER
• Output power :
1.8–50 MHz band SSB/CW/RTTY/FM 5–100 W
AM 2–40 W
144 MHz band SSB/CW/RTTY/FM 5–50 W
AM 2–20 W
440 MHz band SSB/CW/RTTY/FM 2–20 W
AM 2–8 W
• Modulation system :
SSB Balanced modulation
AM Low level modulation
FM Variable reactance modulation
• Spurious emissions :
Below 47.5 MHz Less than –50 dB (typical)
Above 47.5 MHz Less than –60 dB
• Carrier suppression : More than 40 dB
• Unwanted sideband supp. : More than 50 dB
• Microphone connector : 8-pin modular jack (600 Ω)
• KEY connector : 3-conductor 6.35 (d) mm (
1
/4")
• RTTY connector : 3-conductor 3.5 (d) mm (
1
/8")
■ RECEIVER
• Receive system :
SSB/CW/AM/WFM Double superheterodyne
FM Triple superheterodyne
• Intermediate frequencies :
*FM or FM-N mode only
• Receive sensitivity : (pre-amp ON)
Note: SSB, CW and AM modes are measured at 10 dB S/N; FM mode at
12 dB SINAD.
*Except 4–4.5 MHz, 8–9 MHz.
• Squelch Sensitivity : (pre-amp ON)
SSB Less than 5.6 µV
FM Less than 0.32 µV
• Selectivity* :
SSB, CW, RTTY More than 2.4 kHz/–6 dB
Less than 4.8 kHz/–60 dB
AM/FM-N More than 8.0 kHz/–6 dB
Less than 30 kHz/–40 dB
FM More than 12 kHz/–6 dB
Less than 30 kHz/–60 dB
*Without an optional filter unit and with mid bandwidth selected.
• Spurious and image rejection ratio:
HF band 70dB
50 MHz band 65 dB (except IF through)
144/440 MHz band 65 dB
• Audio output power : More than 2.0 W at 10% distortion
(at 13.8 V DC) with an 8 Ω load
• RIT variable range : ± 9.99 kHz
• PHONES connector : 3-conductor 3.5 (d) mm (1/8")/8 Ω
• EXT SP connector : 2-conductor 3.5 (d) mm (
1
/8")/8 Ω
3rd IF
455 kHz*
455 kHz*
—
—
—
MODE
SSB/AM-N/FM
AM/FM-N
CW
RTTY
WFM
1st IF
69.0115 MHz
69.0100 MHz
69.0106 MHz
69.0105 MHz
70.7000 MHz
2nd IF
9.0115 MHz
9.0100 MHz
9.0106 MHz
9.0105 MHz
10.7000 MHz
1 - 1
SECTION 1 SPECIFICATIONS
FM
—
—
0.5 µV
0.25 µV
0.18 µV
0.18 µV
FREQUENCY
0.5 – 1.8 MHz
1.8 – 28 MHz*
28 – 29.999 MHz
50 MHz band
144 MHz band
440 MHz band
SSB/CW/RTTY
—
0.16 µV
0.16 µV
0.13 µV
0.11 µV
0.11 µV
AM
13 µV
2 µV
2 µV
1 µV
1 µV
1 µV
All stated specifications are subject to change without notice or obligation.
Predrive amplifier
(Q101: 2SK2854)
HPF board
D/A converter
(IC2201: M62352GP)
¡PA AND PLL UNITS
FILTER board
MAIN CPU clock
(X2161: CR-636)
MAIN CPU *
(IC 2001: HD6433337YA56F)
MAIN board
3rd IF filter for FM *
(FI791: SFPC455E-TC01)
MIC amplifier
(IC931: µPC5023GS-077-E1)
AF selector switch *
(IC861: BU4052BCFV-E2)
Tx FM PLL IC *
(IC1011: LC7153M-TLM)
Balanced modulator *
(IC1041: NJM1496V)
Discriminator
(X791: CDB455CX24)
FM IF IC *
(IC791: TA31136FN)
RX preamplifier
(IC151: µPC1658G)
1st mixer
(D271: HSB88WSTR)
1st IF filter
(FI511: FI-261)
2nd mixer *
(D551: HSB88WSTR)
2nd IF filter
(FI561: FL-23)
Space for optional filters
FL-100, FL-101, FL-103
FL-233, FL-232
Power amplifers
(Q171, Q172, Q231: SRFJ7044)
DDS IC
(IC101: SC-1246)
BFO DDS IC
(IC901: SC-1287)
PLL IC *
(IC461: LMX2306TMX)
VCO1 *
(Q301: 2SK508)
VCO2 *
(Q331: 2SK508)
PA unit
DRIVER board
Drive amplifers
(Q161, Q211: MRF1508TI)
Predrive amplifer
(Q121: MXR9745)
AF power amplifer
(IC231: LA4425A)
PLL unit
AF volume controller
(IC201: M5282FP)
VCO3 *
(Q361: 2SK508)
Reference oscillator
(X621: CR-275A 30.00000 MHz)
*Located under side of the point
¡MAIN AND FILTER BOARDS
2 - 1
SECTION 2 INSIDE VIEWS
3-1 RECEIVER CIRCUITS
3-1-1 HF/50 MHz RF CIRCUIT
(FILTER, MAIN AND HPF BOARDS)
HF/50 MHz RF filters pass only the desired band signals
and suppress any undesired band signals. The HF/50 MHz
RF circuit has 7 low-pass filters and 8 high-pass filters for
specified band use.
HF/50 MHz RF signals from the [ANT1] connector, pass
through one of 7 low-pass filters as below, the transmit/
receive switching relay (FILTER board; RL1) and low-pass
filter (FILTER board; L1, L2, C1–C5), and are then applied
to the MAIN board via J1 (FILTER board).
The signals from the FILTER board are applied to or bypass
the 20 dB attenuator (R122, R125, R126). The signals pass
through the high-pass filter (L132, L133, C132–C137) to
suppress strong signals below 1.6 MHz and are then applied
to the HPF board via the “SAF” terminal.
(1) 0.03–2 MHz and 30–40 MHz
The signals pass through a low-pass filter (L101, L102,
C101–C105), and then applied to the preamplifier circuit on
the MAIN board.
(2) 2–30 MHz
The signals from the low-pass filter (L101, L102,
C101–C105) are applied to one of 6 high-pass filters as at
right above and are then applied to the preamplifier circuit
on the MAIN board.
(3) 40–60 MHz
The signals pass through the low-pass filter (L172, L173,
C172–C176) and the high-pass filter (L174, L175,
C177–C181) via D171 and are then applied to the preamplifier circuit on the MAIN board.
3-1-2 VHF AND UHF RF CIRCUITS (PA UNIT)
The VHF and UHF RF circuits pass and amplify only the
desired band signals and suppresses any undesired band
signals. The both RF circuits have a preamplifier and bandpass filters respectively.
• VHF RF CIRCUIT
The VHF RF signals from the [ANT2] connector pass
through the low-pass filter (L263–L265, C274–C276) and
antenna switching circuit (D291–D293). The signals are
applied to the bandpass filter (D403, D409, D408), and are
then amplified at the preamplifier circuit (Q403). The amplified signals are then applied to the another bandpass filter
(D407, D406, D410).
• UHF RF CIRCUIT
The UHF RF signals from the [ANT2] connector pass
through the high-pass filter (L316, L317, C326–C327), lowpass filter (L313–L315, C322–C324) and antenna switching
circuit (D341, D342, D343). The signals are amplified at the
preamplifier circuit (Q453) between the 2 bandpass filters
(D454, D453 and D454, D456).
The filtered signals are applied to the MAIN board via J481
(PAunit) and are then applied to the preamplifier circuit.
D403, D408, D409, D406, D407, D410, D454, D453, D454
and D456 are varactor diodes that tune the ceinter frequency of an RF passband for wide bandwidth receiving and
good image response rejection. On the VHF band, receiving
signals are above 129 MHz, the switching diodes (D404,
D405) are turned off by the control signal “2MBL” from PLL
unit, then the varactor diodes (D408, D407) are disconnected.
• Used RF high-pass filter (HPF board)
• Used RF low-pass filter (FILTER board)
3 - 1
SECTION 3 CIRCUIT DESCRIPTION
• RECEIVER CONSTRUCTION
1st LO:
69.0415 MHz–
530.0115 MHz
BPF
LPF
HPF
1st mixer
D271
2nd LO:
60.0 MHz
2nd
mixer
D511
to AM demod.
circuit (D761)
to FM demod.
circuit (IC791)
[ANT1]
0.03–60 MHz
LPF
[ANT2]
60–470 MHz
Crystal
filter
FI511
69.0115 MHz
Crystal
filter
NB
gate
FI561
to WFM detector
circuit (IC631)
to BFO circuit
(IC1041)
9.0115MHz
NB
circuit
FILTER BOARD
PA UNIT
HPF
BOARD
MAIN BOARD
SSB, CW
filter
FI671
AM, FM-N
filter
FI681
Optional
filter-1
Optional
filter-2
amp.
Pre-amp.
IC151
Frequency
(MHz)
0.03–2 MHz
2–4 MHz
4–8 MHz
8–15 MHz
Frequency
(MHz)
15–22 MHz
22–30 MHz
30–60 MHz
Control
signal
L5
L6
L7
Control
signal
L1
L2
L3
L4
Entrance
coil
RL15
RL13
RL5
RL9
Entrance
coil
RL11
RL7
RL3
Frequency
(MHz)
0.03–2 MHz
2–4 MHz
4–8 MHz
8–15 MHz
Frequency
(MHz)
15–22 MHz
22–30 MHz
30–40 MHz
40–60 MHz
Control
signal
L5H
L6H
THH
B7H
Control
signal
THH
L2H
L3H
L4H
Entrance
coil
D111
D121
D131
D141
Entrance
coil
D151
D161
D111
D171
3-1-3 PREAMPLIFIER CIRCUIT (MAIN BOARD)
The preamplifier circuit in the IC-706MKIIG has approx.
15dB gain over a wide-band frequency range.
When the preamplifier is turned ON, the signals from the RF
circuit are applied to the preamplifier (IC151) via D2182.
Amplified or bypassed signals are applied to the 1st mixer
circuit (D271).
3-1-4 1ST MIXER CIRCUIT (MAIN BOARD)
The 1st mixer circuit mixes the receive signals with the 1st
LO signal to convert the receive signal frequencies to a 69
or 70.7 MHz 1st IF signal.
The signals from the preamplifier circuit, or signals which
bypass the preamplifier, are passed through a low-pass filter and then applied to the 1st mixer (D271).
The 1st LO signals
(69.0415–539.0115 MHz)
enter the MAIN board from
the PLL unit via J281. The
LO signal is amplified at
IC281, filtered by a lowpass filter, and then,
applied to the 1st mixer.
3-1-5 1ST IF CIRCUIT (MAIN BOARD)
The 1st IF circuit filters and amplifies the 1st IF signals. The
1st IF signals are applied to a Crystal Filter (FI511) to suppress out-of-band signals.
The 69 MHz 1st IF signals (except WFM) pass through the
crystal filter (FI511), however, the 70.7 MHz 1st IF signal
(WFM) passes through a bandpass filter (L501–L505,
C501–C506). Then the filtered signals are applied to the IF
amplifier (IC521).
The AGC voltage is supplied to the transmit/receive switching circuit (D521, D522) and D521/D522 function as PIN
attenuators for AGC operation.
The amplified signals are then applied to the 2nd mixer circuit (D551) via the bandpass filter (L542–L546,
C542–C545).
3-1-6 2ND MIXER CIRCUIT (MAIN BOARD)
The 2nd mixer circuit mixes the 1st IF signals and 2nd LO
signal (60.00 MHz) to convert the 1st IF to a 2nd IF.
The 1st IF signals from the band pass filter (L542–L546,
C542–C545) are converted to 9 MHz or 10.7 MHz 2nd IF
signals at the 2nd mixer (D551).
The 2nd IF signals are
applied to the bandpass filter (FI561) to suppress
undesired signals, such as
the 2nd LO signal, and are
then applied to the noise
blanker gate (D561,
D562).
While in WFM mode, the IF signals pass through the lowpass filter (L601, C601–C603), IF amplifiers (Q601, Q611),
ceramic filter (FI611). The signals are then applied to the
WFM demodulator circuit (IC631).
3-1-7 NOISE BLANKER CIRCUIT (MAIN BOARD)
The noise blanker circuit detects pulse type noise, and turns
OFF the signal line when noise appears.
Aportion of the signals from FI561 are amplified at the noise
amplifiers (Q621, Q632, amplifier section of IC631), then
detected at the noise detector (D632) to convert the noise
components to DC voltages.
The converted voltages are then applied to the noise
blanker switch (Q634, Q635). At the moment the detected
voltage exceeds Q634’s threshold level, Q635 outputs a
blanking signal to close the noise blanker gate (D561, D562)
by applying reverse-biased voltage.
The detected voltage from D632 is also applied to the noise
blanker AGC circuit (Q631, Q633) and is then fed back to
the noise amplifier (IC631) as a bias voltage. The noise AGC
circuit prevents closure of the noise blanker gate for long
periods by non-pulse-type noise. The time constant of the
noise blanker AGC circuit is determined by R637.
The 2nd IF signals from the noise blanker gate are then
applied to the 2nd IF circuit.
3-1-8 2ND IF CIRCUIT
The 2nd IF circuit amplifies and filters the 2nd IF signals.
The 2nd IF signals from the noise blanker gate (D561,
D562) are amplified at the IF amplifier (IC571) via the Tx/Rx
switch (D572) and applied to a 2nd IF filter as shown below.
The filtered or bypassed signals are applied to the buffer
amplifier (Q721), IF amplifiers (Q731, Q741) and buffer
amplifier (Q751) to obtain a detectable level at the demodulator circuit
The amplified signals from the buffer amplifier (Q751) are
shared between the SSB/CW/RTTY detector (IC841), AM
detector (D761) and AGC detector (D771). Output signals
from the buffer amplifier (Q721) are applied to the FM IF IC
(IC791).
3 - 2
• 1st IF frequency
• 2nd IF frequency
• Used 2nd IF filter
Mode Used filter Control signal
SSB, CW, RTTY
AM nar.
AM, FM nar.
FM
SSB nar.
CW nar., RTTY nar.
SSB wide, CW wide,
RTTY wide
FL-272 (FI671)
FL-94 (FI681)
Bypassed
Optional FL-223
Optional FL-100,
FL101, FL-223,
FL-232
Optional FL-103
2F23
2F80
2FTH
OP1 or OP2
OP1 or OP2
OP1 or OP2
1st IF
69.0115 MHz
69.0100 MHz
69.0106 MHz
69.0105 MHz
70.7000 MHz
Mode
SSB/AM-N/FM
AM/FM-N
CW
RTTY
WFM
2nd IF
9.0115 MHz
9.0100 MHz
9.0106 MHz
9.0105 MHz
10.7000 MHz
Mode
SSB/AM-N/FM
AM/FM-N
CW
RTTY
WFM
3 - 3
3-1-9 IF SHIFT CIRCUIT (MAIN BOARD)
The IF shift circuit shifts the center frequency of IF signals to
electronically shift the center frequency.
The IF shift circuit shifts the 1st LO and BFO within ±1.2 kHz
in SSB/CW/RTTY modes or ±250 Hz in CW-N/RTTY-N
modes. As a result, the 2nd IF (also 1st IF) is shifted from
the center frequency of the 2nd IF filter (FI671, FI681 or
optional IF filters). This means 2nd IF signals do not pass
through the center of the 2nd IF filter. Therefore, the higher
or lower frequency components of the IF are cut out. Since
the BFO frequency is also shifted the same value as the 1st
IF, frequency is corrected at the detector.
In the IC-706MKIIG, the 1st LO frequency is shifted to
change the 2nd IF because a fixed 2nd LO frequency (60
MHz) is used. The 1st IF filter (FI671) and crystal filter
(FI561) have 15 kHz pass-band widths, and do not affect IF
shift operation.
3-1-10 AGC CIRCUIT (MAIN BOARD)
The AGC (Automatic Gain Control) circuit reduces IF amplifier gain to keep the audio output at a constant level. The
receiver gain is determined by the voltage on the AGC line
(Q776 collector).
The 2nd IF signal from the buffer amplifier (Q751) is detected at the AGC detector (D771) and applied to the AGC
amplifier (IC811b). IC811b sets the receiver gain with the
[RF/SQL] control via the “RFGV” signal line.
When receiving strong signals, the detected voltage increases and the AGC voltage decreases via the DC amplifier
(Q776). The AGC voltage is used for the bias voltage of the
transmit/receive switching PIN diodes (D521, D522, D572,
D573) to attenuate the received signals.
When AGC slow is selected, C775 and R778 are connected
in parallel to obtain appropriate AGC characteristics.
3-1-11 S-METER CIRCUIT (MAIN BOARD)
The S-meter circuit indicates the relative received signal
strength while receiving by utilizing the AGC voltage which
changes depending on the received signal strength.
The output voltage of the AGC amplifier (IC811b, pin 7) is
applied to the main CPU (IC2001, pin 36) as an S-meter signal via the analog switch (IC2101, pins 5, 3) as the “SML”
signal. The FM S-meter signal from the FM IF IC (IC791, pin
12) is also applied to the analog switch (IC2101, pin 5) via
the meter amplifier (Q774).
The S-meter signal from the main CPU (IC2001) is applied
to the sub CPU and is then displayed on the S-meter readout.
3-1-12 SQUELCH CIRCUIT (MAIN BOARD)
The squelch circuit mutes audio output when the S-meter
signal is lower than the [RF/SQL] control setting level.
The S-meter signal is applied to the main CPU (IC2001, pin
36) in SSB/CW/RTTY modes and is compared with the
threshold level set by the [RF/SQL] control. The [RF/SQL]
setting is picked up at the sub CPU (DISPLAY board; IC1,
pin 99). The main CPU compares the S-meter signal and
[RF/SQL] setting, and controls the AF selector switch
(IC861) to cut out AF signals via IC2122a.
In FM mode, a portion of the AF signals from the FM IF IC
(IC791, pin 9) are applied to the active filter section (pin 8)
where noise components above 20 kHz are amplified. The
signals are rectified at the noise detector section and then
output from pin 14. The noise squelch signal from pin 14 is
applied to the main CPU (IC2001, pin 31) via the analog
switch (IC2101, pins 14, 13) as the “NSQL” signal. The CPU
then controls the AF selector switch (IC861).
3-1-13 DEMODULATOR CIRCUITS (MAIN BOARD)
(1) SSB/CW/RTTY modes
The 2nd IF signals from the buffer amplifier (Q751) are
mixed with the BFO signal from the PLL unit at the product
detector (IC841, pin 6). The detected AF signals from IC841
(pin 1) are applied to the AF selector switch (IC861, pin 12).
(2) AM mode
The 2nd IF signals from the buffer amplifier (Q751) are
detected at the AM detector (D761). The detected AF signal
is applied to the AF selector switch (IC861, pin 15).
(3) FM/FM NARROW modes
The 2nd IF signals from the buffer amplifier (Q721) are
applied to the FM IF IC (IC791, pin 16) where the IF signals
are converted into 455 kHz IF signals. The signals pass
through FI791 and are applied to the quadrature detector
section. X791 is used for quadrature detector. The detected
AF signals from pin 9 are then applied to the AF selector
switch (IC861, pin 14) via the de-emphasis circuit (IC811a).
(4) WFM mode
The 2nd IF signals from the IF amplifier (Q611) are applied
to the WFM demodulator circuit (IC631, pins 2, 3) where the
IF signals are converted into AF signals. The detected AF
signals from pin 8 are then applied to the AF selector switch
(IC861, pin 11).
• AGC CIRCUIT
AGC line
RFGV
(RF gain control)
AGC
FAST
Q771
8 V
D771
C771
C772
2nd IF
signal
C775 R778Q773
C774 R777Q772
C773 R776
R775
D772
R772
R773
R774
Amp.
AGC
amp.
Q776, Q777
IC811b
“SML”
AGC det.
S-meter signal
3 - 4
3-1-14 AF SELECTOR SWITCH (MAIN BOARD)
The AF signals from one of the detector circuits are applied
to the AF selector switch (IC861). IC861 consists of dual 4channel analog switches which are selected with a mode
signal and the squelch control signal.
3-1-15 AF AMPLIFIER CIRCUIT (PLL UNIT)
The AF amplifier amplifies the demodulated signal to a suitable driving level for the speaker.
The AF signals from the AF selector switch (MAIN board;
IC861) are applied to the PLL unit via the “AFI” signal line.
The CW side tone/beep tone and optional synthesized voice
are also applied to the PLL unit via the “AFBP” signal line.
The AF signals from the MAIN board are applied to the VCA
(Voltage Controlled Amplifier) circuit (IC201). The AF gain
setting from the main CPU is converted to DC voltage at the
D/A converter (MAIN board IC2201) and applied to the VCA
control terminal (IC201, pin 8) via the “AFGC” signal line.
The output AF signal from IC201 (pin 9) is power-amplified
at IC231 to drive the speaker.
3-2 TRANSMITTER CIRCUITS
3-2-1 MICROPHONE AMPLIFIER CIRCUIT
(MAIN BOARD)
The microphone amplifier circuit amplifies microphone input
signals and outputs the amplified signals to the balanced
modulator or FM modulation circuit.
Audio signals from the front or rear panel [MIC] connector
enter the microphone amplifier IC (IC931, pin 22) and are
then amplified at the microphone amplifier or speech compressor section. Compression level is adjusted with the
[COMP GAIN] control (R945).
The amplified or compressed signals are applied to the VCA
section of IC931. The microphone gain setting from the D/A
converter (IC2201, pin 2) is applied to the VCA control terminal (IC931, pin 10). The resulting signals from pin 9 are
then applied to the buffer amplifier (Q961) via the analog
switch (IC1141). External modulation input from the [ACC]
socket (pin 11) is also applied to Q961.
While in SSB mode, the amplified signals from the buffer
amplifier (Q961) are passed through the AF selector switch
(IC971) and are then applied to the balanced modulator
(IC1041).
While in AM/FM mode, the amplified signals from the buffer
amplifier (Q961) are applied to the limiter amplifier (IC981a)
and splatter filter (IC981b). The signals are then applied to
the AF selector switch (IC971) in AM mode or to the varactor diode (D1012) in FM mode.
3-2-2 VOX CIRCUIT (MAIN BOARD)
The VOX (Voice-Operated-Transmission) circuit sets transmitting conditions according to voice input.
When the VOX function is activated, the microphone signals
from IC931 (pin 19) are applied to the VOX comparator section in the main CPU (IC2001, pin 32) via the VOXL line.
A portion of the power amplified AF signals from the AF
power amplifier (PLL unit; IC231) are amplified at the buffer
amplifier (IC931, pins 14, 15) and applied to the anti-VOX
comparator section in the main CPU (IC2001, pin 33) via the
AVXLline.
Then the main CPU compares these and controls the transmitter circuit.
3-2-3 BALANCED MODULATOR (MAIN BOARD)
The balanced modulator converts the AF signals from the
microphone amplifier to a 9 MHz IF signal with a BFO (Beat
Frequency Oscillator) signal.
Microphone signals from the AF selector switch (IC971) are
applied to the balanced modulator (IC1041, pin 1). The BFO
signal from the PLL unit is applied to IC1041 (pin 10) as a
carrier signal.
IC1041 is a double balanced mixer IC and outputs a double
side band (DSB) signal with –40 dB of carrier suppression.
R1045 adjusts the balanced level of IC1041 for maximum
carrier suppression. The resulting signal passes through a 9
MHz IF filter (FI671 in SSB/CW/RTTY modes) to suppress
unwanted side-band signals.
In AM mode, R1042 is connected to upset the balance of
IC1041 via Q1041 for leaking the BFO signal as a carrier
signal. The CW keying/RTTY TX signal is applied to IC1041
pin 1.
• AF selector switch
11
13
INH
15
12
9, 10
14
X3
X2
X0
X
X1
SSB/CW/
RTTY
IC861
FM
WFM
AM
6
AFS1, AFS2
SQL
AFI signal
to PLL unit
• Microphone amplifier
11 2, 3 10
19
22
9
1415
MIC
signal
IC931
[
COMP GAIN
]
(R945)
MIGV from D/A
convertor (IC35)
VOXL
to CPU
AVOXL
to CPU
AFO signal
Amp.
COMP
Buffer
Buffer
Buffer
COMS
from CPU
AMOD
to IC1141
VCA
Buffer
3 - 5
3-2-4 FM MODULATION CIRCUIT (MAIN BOARD)
The microphone signals from Q961 are applied to the limiter
amplifier (IC981a) and the splatter filter (IC981b). The 1750
Hz European tone signal from the main CPU (IC2001 pin
40) is also applied to IC981a pin 2 for European repeaters.
The sub-audible tone signal (67.0–254.1 Hz) from the main
CPU (IC2001 pin 37) is also applied to IC981b pin 5 for
repeater use.
The resulting signals are applied to the VCO circuit (Q1011,
D1012) via R1002 to change the reactance of the varactor
diode (D1012) for FM modulation. The modulated signal is
amplified at the buffer amplifier (Q1013) and bypasses the 9
MHz IF filter.
3-2-5 TRANSMITTER IF CIRCUIT (MAIN BOARD)
The 9 MHz IF signal from the modulation circuit passes
through the 9 MHz IF filter (FI671 in SSB/CW/RTTY modes;
FI681 in AM/FM-N modes; through in FM mode). The signal
is amplified at IC571, and then passes through the total gain
adjustment volume (R579), and the crystal filter (FI561). The
signal is then applied to the 2nd mixer (D551).
The signal is mixed with the 2nd LO signal (60 MHz) and
converted to a 69 MHz IF signal at the 2nd mixer (D551).
The 69 MHz IF signal passes through a bandpass filter, IF
amplifier (IC521) and 69 MHz IF filter (FI511), and is then
converted to the displayed frequency at the 1st mixer (D271)
with the 1st LO signal. The mixers (D271, D551) and IF
amplifiers (IC521, IC571) are used commonly for both
receiving and transmitting.
The ALC voltage is supplied to the transmit/receive switching circuit (D521/D522 and D572/D573). D521/D522 and
D572/D573 function as PIN attenuators for ALC operation.
3-2-6 RF CIRCUIT
(PA UNIT, MAIN AND HPF BOARD)
The RF circuit amplifies the displayed frequency signal to
obtain 100 W of RF output power for HF/50 MHz bands and
50 W for the 144 MHz band, 20 W for the 440 MHz band.
The HF/50 MHz RF signals from the 1st mixer (D271) via the
low-pass filter enter the HPF board and then pass through
one of 8 high-pass filters (Refer to 3-1 for used RF high-pass
filter). The 50 MHz RF signals pass through a low-pass filter
additionally. The filtered signals return to the MAIN board,
are amplified at the YGR amplifier (IC231), and are then
applied to the PAunit.
The 144 MHz RF signals from the 1st mixer (D271) via the
low-pass filter (L251–253, C253–259) bypass the filters and
pass through the bandpass filter (L182–L184, L195, L196,
C181–C186, C195–C197) in the MAIN board. The signals
are amplified at the RF amplifier (IC221) and YGR amplifer
(IC231) and are then applied to the PAunit.
The 440 MHz RF signals from the 1st mixer (D271) via the
low-pass filter (L251–253, C253–259) are amplified at RF
amplifier (IC222) and passed through the bandpass filter
(FI371–FI373) in the MAIN board. The filtered signal is
amplified at the YGR amplifer (IC231) and is applied to the
PA unit.
The signals from IC231 enter the PA unit and is amplified at
the drive amplifiers (Q101, Q121) in sequence. The amplified signals are applied to the band switch (RL1).
The HF/50 MHz RF signals from the band switch (RL1) are
amplified at the drive (DRIVER board; Q161) and power
(Q171, Q172) amplifiers to obtain a stable 100 W of RF output power. The power-amplified signals are then applied to
the [ANT1] connector via one of the 7 low-pass filters in the
FILTER board.
For the 144/440 MHz RF signals from the band switch
(RL1), 50 W for 144 MHz band or 20 W for 440 MHz band
of RF output power is obtained at the drive (DRIVER board;
Q211) and power amplifier (Q231). The power-amplified signals are applied to the [ANT2] connector via the antenna
switching circuit and low-pass (144 MHz band) or high pass
(440 MHz band) filters.
3-2-7 ALC CIRCUIT (MAIN BOARD)
The ALC (Automatic Level Control) circuit reduces the gain
of IF amplifiers in order for the transceiver to output a constant RF power set by the RF power setting even when the
supplied voltage shifts, etc.
The HF/50 MHz RF power signal level is detected at the
power detector (FIL TER board; D9), buffer-amplified at IC1b
and applied to the MAIN board as the “HFOR” voltage.
The 144 MHz and 440 MHz RF power signals are detected
at the power detectors (PA unit; D262, D263) and (PA unit;
D312, D313) respectively. The detected signals are applied
to the MAIN board as the “VFOR” or “UFOR” voltages.
• TRANSMITTER CONSTRUCTION
1st LO
60.0 MHz
BFO
FM tone
D551
IC231
[ANT1]
HF+50 MHz
[ANT2]
144/440 MHz
144 MHz
440 MHz
Q101
Q121
Q171
Q172
Q231
Q1011
D231
IC1041
IC931
Crystal
filter
FI1
FI671, FI681,
or optional filter
MIC
except FM
9.0115 MHz
Crystal
filter
BPF
BPF
LPF
LPF
HPF
BPF
HPF
HPF
PA UNIT
HPF
BOARD
FILTER
BOARD
MAIN BOARD
Amp. Amp. Amp.
Amp.
Q161
Amp.
Amp.
Q211
Amp.
IDC
FM, AM
AM
FM
FM only
50 MHz
144 MHz
SSB
•
•
•
BPF
440 MHz
3 - 6
The “FOR”, “VFOR” and “UFOR” voltages are combined to
the “FORL” voltage and then applied to IC1091b (pin 6). The
“POCV” voltage from the D/A converter (IC2201, pin 3),
determined by the RF power setting, is applied to IC1091b
(pin 5) as the reference voltage.
When the “FORL” voltage exceeds the “POCV” voltage, ALC
bias voltage from IC1091a (pin 1) controls the PIN diodes
(D521, D522, D572, D573) using Q1092. This adjusts the
output power to the level determined by the RF power setting until the “FORL” and “POCV” voltages are equalized.
In AM mode, IC1091a operates as an averaging ALC amplifier with Q1091 and C1091. Q1071 turns ON and the
“POCV” voltage is shifted for 40 W AM output power (maximum, 20 W for 144 MHz band, 8 W for 440 MHz band)
through R1080.
The ALC bias voltage from IC1091a is also applied to the
main CPU (IC2001 pin 34) as the “ALCL” voltage for ALC
meter indication.
An external ALC input (minus voltage) from the [ACC] socket (pin 6) is shifted to plus voltage at D1131 and is applied
to the buffer amplifier (Q1131). External ALC operation is
identical to that of the internal ALC.
3-2-8 APC CIRCUIT (MAIN BOARD)
The APC (Automatic Power Control) circuit protects the
power amplifiers on the PAunit from high SWR and excessive current for the HF/50 MHz band.
The reflected wave signal appears and increases on the
antenna connector when the antenna is mismatched. The
HF/50 MHz reflected signal level is detected at D10 (FILTER
board), and is amplified at the APC amplifier (IC1091c) and
applied to the ALC circuit as the reference voltage.
For the current APC, the driving current at the power amplifier is detected in the voltages (“ICH” and “ICL”) which
appear at both terminals of a 0.012 Ω resistor (R201) on the
PAunit. The detected voltages are applied to the differential
amplifier (IC1091d, pins 13, 12). When the current of the
power amplifier exceeds 22 A, IC1091d controls the ALC
line via IC1091a to prevent excessive current flow.
3-2-9 RF, ALC, SWR METER CIRCUITS
(MAIN BOARD)
While transmitting, RF, ALC or SWR meter readings are
available and can be selected with the [MET] switch.
(1) Power meter
The “FOR”, “VFOR” and “UFOR” voltages are combined to
the “FORL” voltage, and it is then applied to the main CPU
(IC2001, pin 35) via the analog switch (IC2101, pins 11, 13)
for indicating the output power.
(2) ALC meter
The ALC bias voltage from IC1091a pin 1 is applied to the
main CPU (IC2001, pin 34) via the “ALCV” signal line for
indicating the ALC level.
(3) SWR meter
The “FORL” and “REFL” voltages are applied to the main
CPU (IC2001, pins 32 and 36) via the analog switch
(IC2101, pins 11, 13 and 4, 3) respectively. The main CPU
compares the ratio of “FORV” to “REFV” voltage and indicates the SWR for the [ANT1] connector.
3-3 PLL CIRCUITS
3-3-1 GENERAL
The PLL unit generates a 1st LO frequency
(69.0415–530.0115 MHz), a 2nd LO frequency (60 MHz), a
BFO frequency (9.01 MHz), an FM 3rd LO frequency
(9.4665/9.4650 MHz) and a TX FM PLL reference frequency (9.0115/9.0100 MHz).
The 1st LO PLL adopts a mixer-less dual loop PLL system
and has 3 VCO circuits. The BFO uses a DDS and the 2nd
LO uses a fixed frequency double that of the crystal oscillator.
3-3-2 1ST LO PLL CIRCUIT
The 1st LO PLL contains a main loop and reference loop
forming a dual loop system.
The reference loop generates a 10.6605 to 10.683 MHz frequency using a DDS circuit, and the main loop generates a
69.0415 to 269.50575 MHz frequency using the reference
loop frequency.
While operating on 60 MHz and above, the output is doubled
at D531 for oscillating a wide frequency range.
(1) REFERENCE LOOP PLL
The oscillated signal at the reference VCO (Q1, D1) is
amplified at the amplifiers (Q21, Q51) and is then applied to
the DDS IC (IC101, pin 46). The signal is then divided and
detected on phase with the DDS generated frequency.
The detected signals output from IC101 (pin 56) is converted into a DC voltage (lock voltage) at the loop filter (R133,
R134, C133) and then fed back to the varactor diode (D1) in
the VCO circuit.
(2) MAIN LOOP PLL
The oscillated signal at one of the main loop VCOs (Q301,
Q331, Q361) is amplified at the buffer amplifiers (Q10) and
is then applied to the PLL IC (IC461, pin 6). The signal is
then divided and detected on phase with the reference loop
output frequency.
The detected signal output from the PLL IC (IC461, pin 2) is
converted into a DC voltage (lock voltage) at the active loop
filter and then fed back to one of the varactor diodes (D301,
D331, D361) in the VCO circuits. While operating on 60 MHz
and above, the VCO output is doubled at the doubler circuit
(D531) and amplified at the ampolifier (IC541).
The oscillated signal passes through a low-pass or bandpass filter and is then applied to the MAIN board as a 1st LO
signal.
3 - 7
3-3-3 2ND LO AND REFERENCE OSCILLATOR
CIRCUITS
The reference oscillator (X621, Q621) generates a 30.0
MHz frequency used for the 1st LO and BFO circuits as a
system clock and for the 2nd LO signal.
The oscillated signal is amplified at the buffer amplifier
(Q661), and is doubled at Q681 and the 60 MHz frequency
is picked up at the bandpass filter (L681, L682). The 60 MHz
signal is applied to the MAIN board as a 2nd LO signal.
3-3-4 BFO CIRCUIT
The DDS IC (IC901) generates a 10-bit digital signal. The
signal is converted into an analog wave signal at the D/A
converter (R951–R970). The analog wave is passed
through the high-pass filter and low-pass filter. The 9 MHz
BFO signal is then applied to the MAIN board via the “BFO”
signal line.
While transmitting in RTTY mode, the RTTY keying signal is
applied to IC901 pin 3 to shift the generated frequency and
to obtain 2 frequencies for FSK operation.
While receiving in FM or FM narrow mode, the BFO circuit
generates a 9.4665 MHz frequency as the 3rd LO signal.
While transmitting in FM or FM narrow mode, the BFO circuit generates a 9.0115 MHz or 9.0100 MHz frequency as
the TX FM PLL reference frequency, respectively.
69.0415–
539.0115 MHz
(1st LO)
10.665–
10.683 MHz
129.0115–
539.0115 MHz
69.0415–
129.0115 MHz
60.0 MHz
(2nd LO)
[ANT1] [ANT2]
1st mixer
D271
0.03–
60 MHz
60–
470 MHz
9.01 MHz
(BFO)
9.4665 MHz (FM)
9.4650 MHz (FM nar.)
9.0115 MHz (FM)
9.0100 MHz (FM nar.)
to FM IF IC
(IC791)
to TX FM
PLL IC
(IC1011)
IC901
IC101
IC461
Q681
PLL UNIT
MAIN BOARD
Q301
Q331
Q361
Q1
Phase
detector
1
⁄N divider
1
⁄
86
Phase
detector
Main loop PLL
Ref. loop PLL
DDS
2
2
DDS
D/A
BPF
BPF
2nd mixer
D551
Product
detector
IC841
69.0115 MHz
(WFM: 70.7 MHz)
to AF selector switch
Ref. Osc.
30.0 MHz
X621
BPF
1st IF 2nd IF
AF signals
Q621
to WFM detector
(IC631)
• FREQUENCY CONSTRUCTION
• BFO frequency
IF shift: Center, RTTY: Normal polarity
3-4 LOGIC CIRCUITS
3-4-1 BAND SELECTION DATA
(MAIN BOARD AND PLL UNIT)
To select the correct RF low-pass filter, high-pass filter and
VCOs on the PLL unit, the CPU outputs the following band
selection data from the I/O expander (MAIN board; IC2231,
IC2232), the D/Aconverter (MAIN board; IC2201) or DDS IC
(PLL unit; IC101) depending on the display frequency.
The D/A convertor output from IC2201 (pin 18) is doubled at
IC891d to obtain the band voltage for external equipment.
• Band selection data
3-4-2 SUB CPU PORT ALLOCATIONS
(DISPLAY board; IC1)
3 - 8
USB
LSB
CW
CW-R
RTTY
AM
FM
FM nar.
WFM
9.0130
9.0100
9.0106
(–CW pitch frequency)
9.0106
(+CW pitch frequency)
9.008375 (2125 Hz tone)
9.008885 (1615 Hz tone)
No output
9.4665 (3rd LO)
9.4650 (3rd LO)
No output
9.0130
9.0100
9.0106
(–CW pitch frequency)
9.0106
(+CW pitch freqency)
9.0105 (MARK)
9.0100
9.0115 (PLLref.)
9.0100 (PLL ref.)
No output
Mode
RX BFO/3rd LO TX BFO/FM PLL ref.
frequency [MHz] frequency [MHz]
0.03– 1.999999
2.0– 3.999999
4.0– 7.999999
8.0– 10.999999
11.0– 14.999999
15.0– 21.999999
22.0– 29.999999
30.0– 39.999999
40.0– 59.999999
60.0–128.999999
129.0–143.999999
144.0–148.000000
148.000001–
199.999999
400.000000–
470.000000
IC2231,
IC2201 IC101
IC2232
(MAIN) (PLL)
Frequency (MAIN)
[MHz]
HPF LPF 1/2 band
VCO
LPF
BPF LPF voltage BPF
L1
L2
L3
L4
L5
L6
B7W
B7
B8
B9
L1
L2
L3
L4
L5
L6
L7
L8
B9
3.70 V
3.19 V
2.68 V
0 V
2.18 V
1.69 V
1.19 V
0.96 V
VCO1
VCO2
VCO1
VCO2
VCO3
LOF1
LOF2
LOF3
LOF4
LOF5
LOF4
LOF6
1
18
19, 20
80
81
96
97
98
99
Input port for the [SHIFT] control.
Outputs a PTT signal.
Low : While transmitting.
Outputs displaly backlight control signal.
Input port for the [PHONES] jack connection detection.
High : When the headphone or
external speaker is connected
to the [PHONES] jack.
Input port for the [RIT] switch.
Input port for the [PTT] switch on the
microphone.
Input port for the microphone up/down
signal.
Input port for the [AF] control.
Input port for the [RF/SQL] control.
SFTL
PTTS
BU1S,
BU2S
PHNK
RSK
PTTL
FUDL
AFGL
SQLL
Pin Port
Description
number name
3-4-3 I/O EXPANDER PORT ALLOCATIONS
(MAIN board; IC2221)
4
5
6
7
11, 12
13
14
Outputs select signal for the Tx AF
selector switch (IC1141).
Hign : When AM and SSB modes
are selected.
Outputs AM mode select signal.
High : When AM mode is selected.
Outputs FM and FM-N modes select
signal.
High : When FM and FM-N modes
are selected.
Outputs WFM mode select signal.
High : When WFM mode is selected.
Output select signals for the Rx AF
selector switch (IC861).
Outputs non-FM mode select signal.
High : When SSB/CW/RTTY/AM
modes are selected.
Outputs an audio mute signal for the
analog switch (IC971).
High : While transmitting in
CW/RTTY modes.
MODS
AMS
FMS
WFMS
AFS1,
AFS2
UNFM
MINH
Pin Port
Description
number name
PORT
MODE
WFM FM AM SSB/CW/RTTY
AFS1 High High Low Low
AFS2 High High Low Low
40
41
42
43
44
45
46
48
49–51
52
53
54
55
61
62
63
71
74
75
78
79
Outputs 1750 Hz European tone signal.
Outputs a strobe signal for the optional UT-102 (Voice synthesizer unit).
Outputs serial data for the I/O
expanders, optional AT-180/UT-102.
Outputs a clock signal for the I/O
expanders, optional AT-180/ UT-102.
Outputs a strobe signal for the I/O
expander ICs (IC2231, IC2232).
Outputs a strobe signal for the I/O
expander ICs (IC2221, IC2222).
Outputs a strobe signal for the D/A
converter IC (IC2201).
Outputs a strobe signal for the BFO
DDS IC (PLL unit; IC901).
Output mode control signals for the 1st
LO DDS IC (PLL unit; IC101).
Outputs a strobe signal for the 1st LO
DDS IC (PLL unit; IC101).
Outputs a strobe signal for the 1st LO
PLL IC (PLL unit; IC461).
Outputs serial data for the DDS ICs
(PLL unit; IC101, IC901) and PLL IC
(PLL unit; IC461).
Outputs a clock signal for the DDS ICs
(PLL unit; IC101, IC901) and PLL IC
(PLL unit; IC461).
Outputs AGC rate select signal
Low : When AGC fast is selected.
Outputs the NB switch (Q635) control
slignal.
High : When the [NB] is turned ON,
except FM/WFM modes.
Outputs the attenuator circuit control
slignal.
High : When the [ATT] is turned ON.
Outputs a strobe signal for the TX FM
PLL IC (IC1011).
Input port for transmit/receive switching signals for the [ACC] connector.
Low : While transmitting.
Outputs a CW keying signal or RTTY
TX signal.
Output port for CI-V bus line.
Input port for CI-V bus line.
3 - 9
ETON
MSST
MDT
MCK
BSTB
DSST
ASTB
PBST
CON2–
CON0
PDST
PMST
PDT
PCK
AFGS
NBS
ATTS
FMST
SNDS
KDS
LTXD
LRXD
(MAIN unit; IC2001)–Continued
Pin Port
Description
number name
13
14
15
16
17
18
19
20
21
22
23
24
30
31
32
33
34
37
39
Input port for the external paddle
(DASH).
Low : During key down
Input port for the external paddle
(DOT) or straight key.
Low : During key down
Input port for the PLL unlock signal
from the DDS IC (PLL unit; IC101) and
PLL IC (PLL unit; IC461).
Low : while PLL unlock
Input port for transmit control signal
from the optional AT-180/AH-4 antenna tuners.
Input port for the optional antenna
tuner connection detection.
High : When the optional antenna
tuner is connected.
Outputs a squelch control signal for
the external unit.
Input port for the [POWER] switch.
Low : When the [POWER] switch is
pushed.
Outputs the switching relay (PA unit;
RL591) control signal.
High : While power is ON.
Outputs start signal for the optional
AT-180 antenna tuner.
Output port
: Beep audio signals while
receiving.
: CW side tone signals while
transmitting.
Outputs start signal for the optional
AH-4
Outputs squelch mute control signal,
applied to the AF mute switch (MAIN
board; Q772).
Low : While squelch is closed.
Input port for the CTCSS decode signal from the low-pass filter (IC811C).
Input port from the [RTTY] or [MIC]
connector.
High : While transmitting.
Input port for the VOX voltage.
Input port for the anti-VOX voltage.
ALC level input port for the ALC meter
indication.
Outputs subaudible tone signals.
Input port for the optional UT-102
(Voice synthesizer unit) activation signal.
High : During speech synthesis.
3-4-4 MAIN CPU PORT ALLOCATIONS
(MAIN unit; IC2001)
DASK
DOTK
UNLK
TKEY
TCON
SQSS
PWK
POWS
ATST
BEEP
AHST
AFMS
CTCV
SNDL
VOXL
AVXL
ALCV
TONE
SPBK
Pin Port
Description
number name
4-1 PREPARATION BEFORE SARVICING
■ REQUIRED TEST EQUIPMENT
DC power supply
RF power meter
(terminated type)
Frequency counter
RF voltmeter
Standard signal
generator (SSG)
FM deviation meter
Modulation analyzer
Distortion meter
Oscilloscope
Digital multimeter
AC millivoltmeter
DC voltmeter
DC ammeter
Audio generator
Spectram analyzer
Attenuator
External speaker
EQUIPMENT GREDE AND RANGE EQUIPMENT GREDE AND RENGE
4 - 1
SECTION 4 ADJUSTMENT PROCEDURES
Output voltage : 13.8 V DC
Current capacity : 30 A or more
Measuring range : 10–200 W
Frequency range : 1.8–500 MHz
Impedance : 50 Ω
SWR : Less than 1.2 : 1
Frequency range : 0.1–500 MHz
Frequency accuracy : ±1 ppm or better
Sensitivity : 100 mV or better
Frequency range : 0.1–500 MHz
Measuring range : 0.01–10 V
Frequency range : 0.1–30 MHz
Output level : 0.1 µV–32 mV
(–127 to –17 dBm)
Frequency range : 0–500 MHz
Measuring range : 0 to ±5 kHz
Frequency range : At least 500 MHz
Measuring range : 0–100 %
Frequency range : 1 kHz ±10 %
Measuring range : 1–100 %
Frequency range : DC–100 MHz
Measuring range : 0.01–10 V
Imput impeadance : 10 MΩ/DC or beter
Measuring range : 10 mV–10 V
Input impedance :
50 kΩ/V DC or better
Measurement capability: 1 A/50 A
Frequency range : 300–3000 Hz
Measuring range : 1–500 mV
Frequency range : At least 1000 MHz
Spectraum bandwidth : 100 kHz or more
Power attenuation : 50 or 60 dB
Capacity : 150 W or more
Input impedance : 8 Ω
Capacity : 5 W or more
‘‘
CONNECTIONS
Attenuator
50 or 60 dB
Audio
generator
RF power meter
A200 W/50 Ω
DC power supply
AA13.8 V/30 A
Standard signal
aagenerator
FM deviation
AAmeter
Spectrum
analyzer
AC
millivoltmeter
Modulation
aanalyzer
CAUTION:
DO NOT connect the
signal generator while
transmitting.
Speaker
to [EXT SP]
i706MKIIG
to [MIC]
to [DC 13.8 V]
to [ELEC KEY]
to [ANT 1/2]
Keyer
• Microphone connector
• (Rear panel view)
Frequency counter
AM meter
1 A, 30 A
Pin 5
MIC GND
Pin 6
MIC INPUT
–
+
Pin 4
PTT
18
Pin 7
GND
4-2 PLL ADJUSTMENTS
4 - 2
REFERENCE
FREQUENCY
REFERENCE
LOOP LOCK
VOLTAGE
MAIN LOOP
LOCK
VOLTAGE
ADJUSTMENT
ADJUSTMENT ADJUSTMENT CONDITION
MEASUREMENT
VALUE
POINT
UNIT LOCATION UNIT ADJUST
1
2
1
1
2
3
• Display frequency: Any
• L623 (PLL unit) : Center
• Receiving
• Display frequency: 0.0300 MHz
• Mode : USB
• Receiving
• Display frequency
: 128.99999 MHz
• Mode : USB
• Receiving
• Display frequency
: 199.99999 MHz
• Mode : USB
• Receiving
• Display frequency
: 470.00000 MHz
• Mode : USB
• Receiving
PLL
PLL
PLL
Connect an RF voltmeter to check point
P681.
Connect a frequency
counter to check
point P681.
Connect a digital
multimeter or oscilloscope to check point
CP131.
Connect a digital
multimeter or oscilloscope to check point
CP401.
Maximum level
(0 dB or more)
60.000000 MHz
2.0 V
4.0 V
4.0 V
4.0 V
PLL
PLL
PLL
L681,
L682
L601
L623
R602
C4
C306
C335
C367
4-3 TRANSMITTER ADJUSTMENTS
TRANSMIT
TOTAL GAIN
OUTPUT
POWER
CARRIER
SUPPRESSION
ADJUSTMENT
ADJUSTMENT ADJUSTMENT CONDITION
MEASUREMENT
VALUE
POINT
UNIT LOCATION UNIT ADJUST
1
2
1
2
3
4
1
• Display frequency: 14.10000 MHz
• Mode : USB
• [Q1 RF POWER] : H
• Connect an audio generator to
[MIC] connector and set as:
1.5 kHz/3 mV
• Transmitting
• Transmitting
• Display frequency: 14.10000 MHz
• Mode : USB
• [Q2 MIC GAIN] : 5
• Connect an audio generator to
[MIC] connector and set as:
1.5 kHz/30 mV
• Transmitting
• Display frequency
: 52.00000 MHz
• Transmitting
• Display frequency
: 145.00000 MHz
• Transmitting
• Display frequency
: 435.00000 MHz
• Transmitting
• Display frequency
: 14.10000 MHz
• Mode : USB and LSB
• Apply no signal to [MIC] connector.
• Transmitting
Rear
Panel
Rear
Panel
Rear
Panel
Connect an RF
power meter to
[ANT1] connector.
Connect an RF
power meter to
[ANT1] connector.
Connect an RF
power meter to
[ANT2] connector.
Connect a spectrum
analyzer to [ANT1]
connector via an
attenuator.
Maximum RF power
50 W
100 W
100 W
50 W
20 W
Minimum carrier level
MAIN
MAIN
MAIN
L511,
L512,
L562,
L563,
L566
R579
R1082
R1084
R1086
R1088
R1045
4 - 3
• MAIN UNIT
• PLL AND PA UNITS
CP131
CP401
Reference loop lock
voltage check point
Reference frequency
adjustment
C4
P681
L682
L681
C335
C306
C367
Main loop lock
voltage adjustment
Main loop lock
voltage check point
Reference loop lock
voltage adjustment
Reference frequency
check point
2nd LO level
adjustment
R1082
R1084
R1086
R1088
R1045
L511
L512
L562
L563
L566
R579
L623
R602
L601
Transmit total gain
Output power
adjustment
Carrier suppression
adjustment
4 - 4
TRANSMITTER ADJUSTMENTS (continued)
FM VCO
FM
DEVIATION
RESIDUAL
AM
AM
MODULATION
CW
CARRIER
LEVEL
ADJUSTMENT
ADJUSTMENT ADJUSTMENT CONDITION
MEASUREMENT
VALUE
POINT
UNIT LOCATION UNIT ADJUST
1
1
1
2
1
2
3
1
• Display frequency: 29.10000 MHz
• Mode : FM
• [Q1 RF POWER] : H
• [M4 TON] : OFF
• Apply no signal to [MIC] connector.
• Transmitting
• Display frequency: 29.10000 MHz
• Mode : FM
• [Q1 RF POWER] : H
• [M4 TON] : OFF
• [Q2 MIC GAIN] : 5
• Connect an audio generator to
[MIC] connector and set as:
1 kHz/30 mV
• Transmitting
• Display frequency: 29.10000 MHz
• Mode : FM
• [Q1 RF POWER] : H
• [M4 TON] : OFF
• [Q2 MIC GAIN] : 5
• Connect an audio generator to
[MIC] connector and set as:
1 kHz/30 mV and OFF
• Transmitting
• Display frequency
: 14.10000 MHz
• Mode : AM
• [Q1 RF POWER] : H
• [Q2 MIC GAIN] : 5
• Disconnect the plug from J281 on
the MAIN board.
• Apply no signal to [MIC] connector.
• Transmitting
• Connect the plug to J281 on the
MAIN board.
• Apply no signal to [MIC] connector.
• Transmitting
• Connect an audio generator to
[MIC] connector and set as:
1 kHz/30 mV
• Transmitting
• Display frequency: 14.10000 MHz
• Mode : CW
• [Q1 RF POWER] : H
• [Q5 KEY SPEED]: 60
• [M4 BRK] : BK
(semi break-in)
• CW paddle : n
• Connect an RF power meter to
[ANT1] connector.
• Transmit dots for a while using a
paddle.
MAIN
Rear
Panel
MAIN
Rear
Panel
Connect a digital
multimeter to check
point CP1011.
Connect an FM deviation meter to [ANT1]
connector via an
attenuator.
Connect an RF
power meter to
[ANT1] connector.
Connect an osilloscope to check point
CP1041.
Connect an RF
power meter to
[ANT1] connector.
Connect a modulation analyzer to
[ANT1] connector via
an attenuator.
Connect an osilloscope to check point
CP921 and [ANT1]
connector.
1.8 V
±4.5 kHz
Minimum power difference with modulation
and unmodulation.
100 mVp-p
35 W
90 % modulation
At the point where the
CW carrier completely
comes up in a 10
msec. delay after
CP921 voltage comes
up.
MAIN
MAIN
MAIN
MAIN
MAIN
C1022
R1002
adjust in
sequence
L511, L512,
then adjust
L562, L563,
L566.
R1042
R1080
R999
R921
After adjustment, varify the TRANSMIT TOTAL GAIN and OUTPUT POWER adjustments.
10 msec.
Keying (CP921)
4 - 5
• MAIN UNIT
R921
R1042
R1002
R999
R1080
L511
L512
CP1011
CP1041
L562
L563
L566
Residual AM
adjustment
FM VCO
check point
CP921
CW carrier level
check point
AM modulation
check point
AM modulation
pre-setting
FM deviation
adjustment
C1022
FM VCO
adjustment
AM modulation
adjustment
CW carrier level
adjustment
J281
4 - 6
TRANSMITTER ADJUSTMENTS (continued)
IDLING
CURRENT
(for drive
amplifiers)
(for final
amplifiers)
SWR
DETECTION
ADJUSTMENT
ADJUSTMENT ADJUSTMENT CONDITION
MEASUREMENT
VALUE
POINT
UNIT LOCATION UNIT ADJUST
1
2
3
4
5
1
2
3
• Display frequency: 14.10000 MHz
• Mode : USB
• [Q2 MIC GAIN] : 1 (minimum)
• turn R162, R174, R175, R214,
R231 (on the PA unit) to maximum
counterclockwise position.
• Disconnect the plug from J571 on
the PAunit.
• Transmitting
• Display frequency: 145.10000 MHz
• Mode : USB
• [Q2 MIC GAIN] : 1 (minimum)
• Transmitting
• Display frequency: 14.10000 MHz
• Mode : USB
• [Q2 MIC GAIN] : 1 (minimum)
• Transmitting
• Transmitting
• Display frequency: 145.10000 MHz
• Mode : USB
• [Q2 MIC GAIN] : 1 (minimum)
• Transmitting
• Display frequency: 14.10000 MHz
• Mode : USB
• Ground CP1071 on the MAIN board.
• Connect an audio generator to
[MIC] connector and set as:
1.5 kHz/30 mV
• Transmitting
• Transmitting
PA
Rear
Panel
FILTER
Connect a DC
ammeter between
the DC power supply
and transceiver’s DC
power socket (P601
on the PAunit).
Connect an RF
power meter to
[ANT1] connector.
Connect a digital
multimeter to check
point W16.
0.5 Aincrease from that
R162 is in maximum
counterclockwise position.
1.0 A increase from
step 1.
1.0 Aincrease from that
R174 is in maximum
counterclockwise position.
1.0 A increase from
step 3.
2.0 A increase from
step 4.
100 W
Minimum voltage
PA
Quick
set
mode
FILTER
R162
R214
R174
R175
R231
Q2 MIC
GAIN
C58
After remove the jumper wire from CP1071 on the MAIN board.
4 - 7
• MAIN AND FILTER UNITS
• PA UNIT
C58
R162
R214
R174
R175
R231
J571
CP1071
Drive idling
adjustment
Final idling
adjustment
SWR detection
pre-setting
Idling current
pre-setting
W16
SWR detection
check point
SWR detection
adjustment
4-4 RECEIVER ADJUSTMENTS
*This output level of the standard signal generator (SSG) is indicated as SSG’s open circuit.
RECEIVER
TOTAL GAIN
WFM
RECEIVING
NOISE
BLANKER
Muximum AF output
level
30 dB of AF level difference
4.0 V
Adjust the maximum
noise wave displayed
on the oscilloscope.
At the point where the
noise just reduces.
1
2
1
1
2
• Display freq. : 14.10000 MHz
• Mode : USB
• [RIT] : OFF
• [M4 AGC] : Fast (F AGC)
• [M3 NB] : OFF
• [P.AMP/ATT] : Preamp ON
• Connect a standard signal generator to the [ANT1] connector and set
as:
Frequency : 14.10150 MHz
Level :
0.5 µV* (–113 dBm)
Modulation : OFF
• Receiving
• [P.AMP/ATT] : Preamp OFF
• Set an SSG as:
Frequency : 14.10150 MHz
Level :
500 µV* (–53 dBm)
and OFF
Modulation : OFF
• Receiving
• Display freq. : 14.10000 MHz
• Mode : WFM
• Set an SSG as:
Frequency : 14.10000 MHz
Level :
500 µV* (–53 dBm)
Modulation : OFF
• Receiving
• Display freq. : 14.10000 MHz
• Mode : USB
• [P.AMP/ATT] : Preamp ON
• [M3 NB] : OFF
• R623 (MAIN) : Center
• Connect an SSG to the [ANT1] connector and set as:
Frequency : 14.1015 MHz
Level : 18 µV* (–82 dBm)
Modulation : OFF
and apply the following signal to
the [ANT1] connector.
• Receiving
• [M3 NB] : ON
• Set an SSG as:
Level : 10 µV* (–87 dBm)
Modulation : OFF
• Receiving
L731,
L741
R741
L632
L621,
L633
R623
Connect an AC millivoltmeter to the [EXT
SP] jack with an 8 Ω
dummy load.
Connect an AC millivoltmeter to the [EXT
SP] jack with a 8 Ω
dummy load.
Connect a digital
multimeter or oscilloscope to check point
CP631.
Connect an oscilloscope to check point
CP632.
MAIN
MAIN
MAIN
MAIN
MAIN
Rear
Panel
Rear
Panel
MAIN
MAIN
ADJUSTMENT
ADJUSTMENT ADJUSTMENT CONDITION
MEASUREMENT
VALUE
POINT
UNIT LOCATION UNIT ADJUST
4 - 8
1 msec.
100 msec.
4 - 9
• MAIN UNIT
CP631
L632
R741
L741
L731
L621
L633
CP632
Receiver total gain
adjustment
Noise blanler
check point
Noise blanler
adjustment
WFM receiving
adjustment
WFM receiving
check point
4-5 SET MODE ADJUSTMENT
4 - 10
ENTERING
ADJUSTMENT
SET MODE
Id APC
FILTER
CALIBRATION
POWER
METER
(14 MHz)
TUNING
POWER
(14 MHz)
(50 MHz)
POWER
METER
(145 MHz)
POWER
METER
(430 MHz)
ALC METER
SWR METER
ADJUSTMENT ADJUSTMENT CONDITION DISPLAY OPERATION
• Enter adjustment set mode:
1 Turn power OFF.
2 Terminate the [REMOTE] jack with a
3.5(d) mm mini-plug.
3 While pushing [P.AMP/ATT] and
[TUNE/CALL], turn power ON.
• Connect an RF power meter to [ANT1]
connector.
• Connect a DC ammeter between the DC
power supply and transceiver’s DC power
socket (P601 on the PAunit).
• Transmit using an external PTT switch.
• Connect an RF power meter to [ANT1]
connector.
• Connect an RF power meter to [ANT1]
connector.
• Transmit using an external PTT switch.
• Transmit using an external PTT switch.
• Connect an RF power meter to [ANT1]
connector.
• Transmit using an external PTT switch.
• Transmit using an external PTT switch.
• Connect an RF power meter to [ANT2]
connector.
• Transmit using an external PTT switch.
• Transmit using an external PTT switch.
• Connect an RF power meter to [ANT2]
connector.
• Transmit using an external PTT switch.
• Transmit using an external PTT switch.
• Connect an RF power meter to [ANT1]
connector.
• Connect an audio generator to [MIC] con-
nector and set as :
Level : 1.5 kHz/30mV
• Transmit using an external PTT switch.
• Connect a 50 Ω dummy load or power
meter to [ANT1] connector.
• Connect a 50 Ω dummy load or power
meter to [ANT1] connector.
1
1
1
1
2
1
2
1
2
1
2
1
1
2
SET IdAPC
GO FILTER CAL
SET 90 %
SET 50 %
SET TUNE Po
SET TUNE Po
SET 90 %
SET 50 %
SET 90 %
SET 50 %
ALC START
SWR 1 LOAD
SWR 2 LOAD
Push [F-3 (TX)] to enter the TX
adjustment setting mode.
Then advance to the following setting, or push [UP]/[DN] to scroll the
display.
Set a total current at 15 Aby adjusting R1125 on the MAIN board.
Push [MENU] to set the "SET
IdAPC" after returning receiving condition.
Push and hold [MENU (GO)] to
make the calibration.
• Transceiver transmits for a while.
Set to 90 W using [MAIN DIAL], then
push [MENU] while transmitting.
Set to 50 W using [MAIN DIAL], then
push [MENU] while transmitting.
Set to 10 W using [MAIN DIAL], then
push [MENU] while transmitting.
Set to 10 W using [MAIN DIAL], then
push [MENU] while transmitting.
Set to 45 W using [MAIN DIAL], then
push [MENU] while transmitting.
Set to 25 W using [MAIN DIAL], then
push [MENU] while transmitting.
Set to 18 W using [MAIN DIAL], then
push [MENU] while transmitting.
Set to 10 W using [MAIN DIAL], then
push [MENU] while transmitting.
Push and hold [MENU] to set ALC
reference level while transmitting.
Push [MENU] to set SWR reference
level.
Push [MENU] to set SWR2 level.
• The display returns to the same as
the ADUSTMENT SET MODE above.
USB
RX TX
Push [F-1 (EXIT)] to exit adjustment set mode.
SET MODE ADJUSTMENT (continued)
ENTERING
ADJUSTMENT
SET MODE
SENSITIVITY
S-METER
• Enter adjustment set mode:
1 Turn power OFF.
2 Terminate the [REMOTE] jack with a
3.5(d) mm mini-plug.
3 While pushing [P.AMP/ATT] and
[TUNE/CALL], turn power ON.
• Connect a standard signal generator to
[ANT2] and set as :
Frequency : 60.05150 MHz
Modulation : OFF
• Receiving
• Connect an SSG to [ANT1] connector and
set as:
Frequency : 14.1515 MHz
Level : OFF
• Receiving
• Set an SSG as :
Level : 50 µV (–73 dBm)
Modulation : OFF
• Receiving
• Set an SSG as :
Level : 50 mV (–13 dBm)
Modulation : OFF
• Receiving
VHF1 BPF1 L
S0 LEVEL
S9 LEVEL
+60dB LEVEL
Push [F-2 (RX)] to enter the RX
adjustment setting mode.
Then advance to the following setting, or push [UP]/[DN] to scroll the
display.
Set a connected SSG’s level at 10
dB of S/N ratio with AC millivoltmeter.
Set maximum AF level using the
[MAIN DIAL], then push [MENU] to
set the "VHF1 BPF1 L".
Push [MENU] to set the "S0 level".
Push [MENU] to set the "S9 level".
Push [MENU] to set the "+60 dB
level".
• The display returns to the same as
the ADUSTMENT SET MODE above.
Push [F-1 (EXIT)] to exit adjustment set mode.
4 - 11
ADJUSTMENT ADJUSTMENT CONDITION DISPLAY OPERATION
1
1
2
3
1
2
3
USB
RX TX
• Same operation as step 2 for the listed BPFs.
• Set an SSG as:
Modulation : OFF
VHF1 BPF2 L : 60.05150 MHz
VHF1 BPF1 M : 90.50150 MHz VHF1 BPF2 M : Same as left
VHF1 BPF1 H : 128.9515 MHz VHF1 BPF2 H : Same as left
VHF2 BPF1 L : 129.1015 MHz VHF2 BPF2 L : Same as left
VHF2 BPF1 M : 145.1515 MHz VHF2 BPF2 M : Same as left
VHF2 BPF1 H : 170.0015 MHz VHF2 BPF2 H : Same as left
UHF BPF1 L : 400.0015 MHz UHF BPF2 L : Same as left
UHF BPF1 M : 435.1515 MHz UHF BPF2 M : Same as left
UHF BPF1 H : 470.0015 MHz UHF BPF2 H : Same as left
• Receiving
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