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SECTION 4 CIRCUIT DESCRIPTION

4 - 1

4-1 RECEIVER CIRCUITS

4-1-1 ANTENNA SWITCHING CIRCUIT

(MAIN UNIT)

The antenna switching circuit functions as a low-pass filter
while receiving and as resonator circuit while transmitting.
The circuit does not allow transmit signals to enter receiver
circuits.

Received signals enter the MAIN unit from the antenna con-
nector and pass through the low-pass filter (L13, L14, L32,
C107–C111, C280). The signals are then applied to the RF
circuit via the antenna switching circuit (D15, L15, C197,
C198).

4-1-2 RF CIRCUIT (MAIN UNIT)

The RF circuit amplifies signals within the range of frequen-
cy coverage and filters out-of-band signals.

The signals from the antenna switching circuit pass through
a tunable bandpass filter (D19, L16, L17, L19, L20,
C199–C204, C206–C210) where the object signals are led
to the RF amplifier circuit (Q27).

The amplified signals at Q7 are applied to the 3-stage tun-
able bandpass filter (D20, L21, L22, L24, L25, C213–C218,
C220–C224) to suppress unwanted signals and improve the
selectivity. The signals are then applied to the 1st mixer cir-
cuit.

4-1-3 1ST MIXER AND 1ST IF CIRCUITS

(MAIN UNIT)

The 1st mixer circuit converts the received signal to a fixed
frequency of the 1st IF signal with a 1st LO (VCO output) fre-
quency. By changing the 1st LO frequency, only the desired
frequency will be passed through two crystal filters at the
next stage of the mixer.

The signals from the RF circuit are mixed with the VCO sig-
nals at the 1st mixer circuit (Q1) to produce a 21.7 MHz 1st
IF signal.

The 1st IF signal is applied to two crystal filters (FI1, FI2) to
suppress out-of-band signals and is then amplified at the IF
amplifier (Q2). The amplified signal is applied to the 2nd
mixer circuit (IC1).

4-1-4 2ND IF AND DEMODULATOR CIRCUITS

(MAIN UNIT)

The 2nd mixer circuit converts the 1st IF signal to a 2nd IF
signal. A double superheterodyne system (which converts
receive signals twice) improves the image rejection ratio and
obtains stable receiver gain.

The FM IF IC (IC1) contains the 2nd local oscillator, 2nd
mixer, limiter amplifier, quadrature detector, and noise
detector circuits, etc.

The 1st IF signal from Q2 is applied to the 2nd mixer section
of IC1 (pin 16), and is mixed with a 21.25 MHz 2nd LO sig-
nal generated at the PLL circuit using the reference fre-
quency (21.25 MHz) to produce a 450 kHz 2nd IF signal.

The 2nd IF signal from IC1 (pin 3) is passed through the
ceramic filter (FI3), where unwanted signals are sup-
pressed, and is then applied to the 2nd IF (limiter) amplifier
in IC1 (pin 5). The signal is applied to the FM detector sec-
tion in IC1 for demodulation into AF signals.

The FM detector circuit employs a quadrature detection
method (linear phase detection), which uses a ceramic dis-
criminator (X1) for phase delay to obtain a non-adjusting cir-
cuit. The detected signal from IC1 (pin 9) is applied to the AF
circuit.

Mixer

16

Limiter
amp.

2nd IF filter
450 kHz

PLL IC

IC2

X2

21.25 MHz

X1

(21.25 MHz)

RSSI

IC1 TA31136F

14

1st IF (21.7 MHz)
from the IF amplifier (Q2)

"SQL" signal to the CPU 
(LOGIC board; IC1,pin 90)

11

10

9

8

7

5

3

AF signal "DET"

R5

Squelch level

adjustment pot

(R16)

2

17

16

Active
filter

FI3

Noise

detector

FM

detector

C25

C26

C24

C28

R20

R18

C27

R15

R21

C20

R19

R14

C266

• 2ND IF AND DEMODULATOR CIRCUITS

Содержание IC-M401EURO

Страница 1: ...SERVICE MANUAL VHF MARINE TRANSCEIVER ...

Страница 2: ...supply when connecting 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 REPAIR NOTES 1 Make sure a problem is internal before disassembling the transceiver 2 DO NOT open the transceiver until the transceiver is dis connected from its power source 3 DO NOT force any of the variable components Turn them slowly...

Страница 3: ...DURES 5 1 PREPARATION 5 1 5 2 PLL ADJUSTMENTS 5 2 5 3 TRANSMITTER ADJUSTMENTS 5 3 5 4 RECEIVER ADJUSTMENTS 5 3 SECTION 6 PARTS LIST 6 1 IC M401EURO 6 1 6 2 HM 132 6 5 SECTION 7 MECHANICAL PARTS AND DISASSEMBLY 7 1 IC M401EURO 7 1 7 2 HM 132 7 3 SECTION 8 SEMI CONDUCTOR INFORMATION SECTION 9 BOARD LAYOUTS 9 1 VR A BOARD 9 1 9 2 VR B BOARD 9 1 9 3 HM 132 9 1 9 4 LOGIC BOARD 9 2 9 5 MAIN UNIT 9 4 SEC...

Страница 4: ...um frequency deviation 5 0 kHz Frequency stability Less than 0 25 µW Spurious emissions 70 dBc Residual modulation 40 dB Audio harmonic distortion Less than 10 at 60 deviation Audio frequency response 1 dB to 3 dB of 6 dB octave from 300 Hz to 3000 Hz RECEIVER Receive system Double conversion superheterodyne system Intermediate frequencies 1st 21 7 MHz 2nd 450 kHz Sensitivity Less than 2 dBµ emf t...

Страница 5: ...00 157 150 157 150 157 200 157 250 157 300 157 350 157 400 156 025 156 025 156 075 156 075 156 125 156 125 156 175 156 175 156 225 156 225 156 275 156 275 156 325 156 325 156 375 156 425 156 475 156 525 156 575 156 625 Receive 161 700 157 100 161 750 157 150 161 800 161 850 161 900 161 950 162 000 160 625 156 025 160 675 156 075 160 725 156 125 160 775 156 175 160 825 156 225 160 875 156 275 160 9...

Страница 6: ...I3 CFWS45QF 1st mixer Q1 3SK272 Antenna switching circuit 1st IF filter FI1 FI2 FL 310 YGR amplifier Q11 2SC3268 AF power amplifier IC9 LA4425A Pre driver Q10 2SC3775 3 PLL IC IC2 PD3140GS EEPROM IC2 HN58X2432TI VR A board VR B board MAIN MPU IC1 HD6473847RH System clock X1 CR 691 Speaker Reset IC IC6 S 80942A NMP DD6 LOGIC board ...

Страница 7: ...12 kg of torque MUST be applied to ensure water resistance REMOVING THE MAIN UNIT Remove the shield cover Unsolder DC cable 4 points and antenna connector B 2 points as shown below Unscrew 2 screws C and 6 screws D to remove the MAIN unit A C B D Slide the case free of the chassis in the direction of the arrow ...

Страница 8: ...al The 1st IF signal is applied to two crystal filters FI1 FI2 to suppress out of band signals and is then amplified at the IF amplifier Q2 The amplified signal is applied to the 2nd mixer circuit IC1 4 1 4 2ND IF AND DEMODULATOR CIRCUITS MAIN UNIT The 2nd mixer circuit converts the 1st IF signal to a 2nd IF signal A double superheterodyne system which converts receive signals twice improves the i...

Страница 9: ... to obtain the pre emphasis charac teristics The amplified signals are passed through the MIX circuit IC10A pins 2 1 to do amplitude limiting and are then applied to the splatter filter IC10B pin 5 to suppress unwanted 3 kHz or higher signals The filtered signals are then applied to the modulation circuit 4 2 2 MODULATION CIRCUIT MAIN UNIT The modulation circuit modulates the VCO oscillating signa...

Страница 10: ...put signal with a refer ence frequency and then outputs the out of phase signal pulse type signal from pin 8 The pulse type signal is converted into DC voltage lock voltage at the loop filter R29 R31 R41 C41 C42 C50 C51 and is then applied to varactor diodes D3 D4 of the VCO to stabilize the oscillated frequency The lock voltage from the loop filter is amplified at the buffer amplifier Q7 and then...

Страница 11: ...mputer and contains LCD driver serial I O timer A D converter programmable I O ROM and RAM SYSTEM CLOCK CIRCUIT X1 is a ceramic oscillator and oscillate 9 8304 MHz system clock for the CPU IC1 RESET CIRCUIT IC6 is a reset IC When turn power ON IC6 outputs a reset signal LOW pulse to the CPU IC1 pin 15 via the RES line LOW BATTERY DETECTOR VCC voltage is divided by R74 R75 and is applied to the low...

Страница 12: ...smit mute signal High While transmitting Input port for DS 100 data Outputs cloning data signal Input port for the squelch volume level Input port from the FM IF IC MAIN unit IC1 for the squelch operation Input port for the connected power supply voltage detection low battery indicator Input port for TX LED control signal 93 94 95 96 97 98 99 Input port for the HM 132 functions 2 02 V UP is pushed...

Страница 13: ...IPMENT Audio generator Standard signal generator SSG Oscilloscope AC millivoltmeter External speaker Attenuator Dummy load GRADE AND RANGE Frequency range 300 3000 Hz Measuring range 1 500 mV Frequency range 0 1 300 MHz Output level 0 1 µV 32 mV 127 to 17 dBm Frequency range DC 20 MHz Measuring range 0 01 20 V Measuring range 10 mV 10 V Input impedance 4 Ω Capacity 5 W or more Power attenuation 40...

Страница 14: ... Output power Low Transmitting Operating channel ch16 Output power Low Connect an RF power meter or a 50 Ω dummy load to the antenna connector Transmitting MAIN Rear Panel Connect a digital multi meter or oscil loscope to the check point CP1 Loosely couple the frequency counter to the antenna con nector 1 8 V 1 6 V 156 8000 MHz MAIN Verify C36 C36 Reference frequency adjustment CP1 PLL lock voltag...

Страница 15: ...nnect a DC volt meter to the check point CP2 Less than 0 56 µV 0 8 V MAIN Verify R16 This output level of a standard signal generator SSG is indicated as SSG s open circuit 5 3 TRANSMITTER ADJUSTMENTS OUTPUT POWER FREQUENCY DEVIATION ADJUSTMENT ADJUSTMENT ADJUSTMENT CONDITION MEASUREMENT VALUE POINT UNIT LOCATION UNIT ADJUST 1 1 Operating channel ch16 Output power High Transmitting Operating chann...

Страница 16: ...5 4 R71 Output power adjustment R138 Frequency deviation adjustment R16 Squelch level adjustment CP2 Squelch level check point J2 PTT 4 1 r q AC millivoltmeter 2 200 mV Audio generator 300 Hz to 3 kHz ...

Страница 17: ...003560 S RESISTOR ERJ3GEYJ 103 V 10 kΩ S Surface mount R62 7030004120 S RESISTOR ERJ3GEYJ 203 V 20 kΩ R63 7030004120 S RESISTOR ERJ3GEYJ 203 V 20 kΩ R64 7030004120 S RESISTOR ERJ3GEYJ 203 V 20 kΩ R65 7030004120 S RESISTOR ERJ3GEYJ 203 V 20 kΩ R66 7030004120 S RESISTOR ERJ3GEYJ 203 V 20 kΩ R67 7030004120 S RESISTOR ERJ3GEYJ 203 V 20 kΩ R68 7030004120 S RESISTOR ERJ3GEYJ 203 V 20 kΩ R69 7030004120 S...

Страница 18: ... 3 L2 6200002410 S COIL NL 252018T 056J L3 6200002430 S COIL NL 252018T 082J L4 6200003090 S COIL NL 322522T 2R7J 3 L5 6200008190 S COIL 0 25 1 9 8TL 80N L6 6200009180 S COIL ELJRE R10J F3 L7 6200009180 S COIL ELJRE R10J F3 L8 6200009180 S COIL ELJRE R10J F3 L9 6200002430 S COIL NL 252018T 082J L10 6200002430 S COIL NL 252018T 082J L11 6170000230 COIL LW 25 L12 6110001600 COIL LA 243 L13 611000160...

Страница 19: ...03450 S RESISTOR ERJ3GEYJ 122 V 1 2 kΩ R151 7030003600 S RESISTOR ERJ3GEYJ 223 V 22 kΩ R152 7030003800 S RESISTOR ERJ3GEYJ 105 V 1 MΩ R154 7030000100 S RESISTOR MCR10EZHJ 4 7 Ω 4R7 R155 7030003560 S RESISTOR ERJ3GEYJ 103 V 10 kΩ R157 7030003280 S RESISTOR ERJ3GEYJ 470 V 47 Ω R158 7030003320 S RESISTOR ERJ3GEYJ 101 V 100 Ω R163 7030003440 S RESISTOR ERJ3GEYJ 102 V 1 kΩ R165 7030003680 S RESISTOR ER...

Страница 20: ...C1608 JB 1E 103K T A C160 4030007130 S CERAMIC C1608 CH 1H 101J T A C162 4030011600 S CERAMIC C1608 JB 1C 104KT N C164 4030009490 S CERAMIC C1608 JB 1H 821K T A C165 4030006880 S CERAMIC C1608 JB 1H 472K T A C166 4030007100 S CERAMIC C1608 CH 1H 560J T A C168 4030006860 S CERAMIC C1608 JB 1H 102K T A C169 4030006900 S CERAMIC C1608 JB 1E 103K T A C170 4510004630 S ELECTROLYTIC ECEV1CA100SR C171 45...

Страница 21: ...7170 S CERAMIC C1608 CH 1H 221J T A C293 4030006850 S CERAMIC C1608 JB 1H 471K T A C294 4030007170 S CERAMIC C1608 CH 1H 221J T A C295 4030009510 S CERAMIC C1608 CH 1H 010B T A C296 4030007120 S CERAMIC C1608 CH 1H 820J T A C297 4030007120 S CERAMIC C1608 CH 1H 820J T A C298 4030006860 S CERAMIC C1608 JB 1H 102K T A C299 4030011600 S CERAMIC C1608 JB 1C 104KT N C300 4030017200 S CERAMIC GHM1030 R ...

Страница 22: ...E 1 MP2 8930055600 2438 Key board A 1 MP3 8310050810 2438 Window plate 1 MP4 8610011030 Knob N 286 BLACK 2 8610011040 Knob N 286 A WHITE 2 MP5 8930014280 SP net 1 MP6 8810008660 Screw PH B0 M3x8 NI ZU BT 4 MP7 8830001580 Sonicrock SL M3 5 8 4 MP10 8110007580 2490 E cover BLACK 1 8110007610 2490 E cover A WHITE 1 MP12 8930052280 O ring AC 2 MP13 8310051220 2438 C Bush plate 1 MP14 8610009240 Knob s...

Страница 23: ...ARD DS1 L MP1 L MP3 L MP14 C W3 F MP14 C MP14 C W1 C MP14 C MP15 C MP2 M MP10 C MP16 C MP25 C MP26 C IC3 M W1 C MP20 C MP3 C MP5 C J1 C MP28 C W2 C MAIN UNIT MP17 C MP7 C MP2 C MP8 C UNIT abbreviations C CHASSIS PARTS L LOGIC BOARD M MAIN UNIT VA VR A BOARD VB VR B BOARD F FRONT UNIT MP15 C MP22 C W1 C MP4 F R1 VB MP3 F R1 VA MP1 F MP13 F MP3 M MP4 M MP5 F MP24 C MP27 C MP23 C MP5 M MP5 M MP6 M 7 ...

Страница 24: ...5 MP13 8850001850 ICOM washer Y 5 MP14 8930052340 O ring AE 5 MP15 8930052350 O ring AF 1 MP16 8930056460 2449 MIC sheet 1 MP17 8930054910 2449 SP Rubber 1 MP18 8850001610 Spring washer M4 SUS 1 MP19 8810009260 Screw PH B0 2 6 NI BT 3 MP21 8810009240 Screw BiH M4 10 ZK 1 MP23 8810008900 Screw PH M3 6 NI 1 REF NO CHASSIS PARTS ORDER NO DESCRIPTION QTY REF NO MC1 7700002500 Microphone KUC3523 040245...

Страница 25: ...E C B E C 2SC4081 R Symbol BR 2SC4116 BL Symbol LL B E C 2SC4226 R25 Symbol R25 2SK1069 4 Symbol FJ G1 G2 S D 3SK272 Symbol DU B E C DTA144 EU Symbol 16 B E C DTA114 EU Symbol 16 B E C DTC114 EU Symbol 24 B E C DTC144 EU Symbol 26 DTC114 TU Symbol 04 B E C D G S B B E E C C DIODES DA204 U Symbol K MA77 Symbol 4B A K HVU350B Symbol BO HSM88ASR Symbol C3 A C 1SS355 Symbol A 1SS375 Symbol FH DSA3A1 M...

Страница 26: ...ARD LAYOUTS 9 1 VR A BOARD 9 2 VR B BOARD 9 3 HM 132 TOP VIEW BOTTOM VIEW 1 B 5585B R1 W1 GND GND VOL2 VOL1 HVS 5 W1 1 to Main unit J5 1 W1 R1 B 5586B GND SQLV 5V 3 W1 1 to Main unit J5 R1 R2 R3 R4 C1 S4 S2 MC1 S 3 S1 ...

Страница 27: ... C24 X1 R46 R47 C14 R78 R76 R4 D4 C4 C3 C6 J1 J1 1 C5 D5 D6 C1 D3 D2 Q9 Q6 C25 C26 R36 R3 Q5 Q7 R77 R6 D1 C9 R34 IC7 IC4 R39 R89 R2 R79 C11 C13 R35 Q3 R83 R10 C20 R75 R74 R1 C2 B5679A ICOM J4 J4 SP SP BPLVL VCC 5V GND GND TMUT TXDET HI LO SQLV PTT BPFV SQL UNLK PSTB SP SP BEEPM VCC 5V RCV SEND GND GND ATIS PTTM RMUTM GND PDATA PCK 40 2 39 J4 1 to Main unit J6 J3 From HM 132 DATAS DATAS DATAM DATAM...

Страница 28: ...9 3 BOTTOM VIEW DS1 DS3 DS4 DS5 DS7 DS8 DS6 ...

Страница 29: ...R68 R69 R74 R37 C100 C101 C202 C207 C226 C11 C10 C9 C258 C60 C259 L7 C61 R33 C260 C32 R27 C38 R135 R137 R136 C45 R39 C33 C34 R169 R91 R81 R82 C128 R87 C135 R95 R93 C137 C140 R165 C39 R46 R42 R47 C51 L6 R52 R163 C214 R157 C253 C212 C211 R187 W8 C213 C215 C223 C224 R188 C254 R7 C6 C3 C4 L27 R5 R6 C5 C19 C20 C21 R14 R22 C29 C30 C204 C203 W6 C208 C206 R185 C252 R155 C227 C228 L26 R158 R3 C225 R190 C25...

Страница 30: ... C284 C81 C286 C285 C87 C98 R150 R149 R213 R210 C265 C264 C86 C85 C172 C173 C287 C174 C164 R131 R206 R183 R172 C282 R203 R207 R204 R126 C160 R123 R121 C159 C276 R201 R113 R122 C175 C288 C290 C289 C292 C291 C116 C115 C188 C293 C187 C118 C281 C278 R174 R176 R175 C236 C237 C165 C166 R133 R132 C235 C233 C234 R171 C162 C155 R130 R129 R177 C103 R73 R65 C280 C109 C197 C107 D16 L21 MP7 D5 D6 L24 L25 C300 ...

Страница 31: ...T HI LO T5 TMUT Q16 DTC144EU Q14 DTC144EU Q12 2SB1143 S Q15 FMW1 R5 T5 RCV SEND VR A BOARD D11 DSA3A1 IC8 TA7805F Q24 2SA1588 GR Q25 DTC144EU Q22 2SA1588 GR Q23 DTC144EU HV 5V VCC ANT BPFV Q1 3SK272 D10 XB15A308 D15 XB15A308 Q27 2SC4226 R25 T5 MPU IC1 HD6473847RH PTT DECODER MULTI RESET EEPROM D A BUFF GPS GATE CTRL BUFF MIC AMP RS CTRL T5 CTRL 5 REG REVERSE CONECT PROTECT PWR AMP LEVEL CONV FM DE...

Страница 32: ...I NMEAI VCC VCC TAG SCN 5V 5V ATIS DSENC1 DSENC2 DSENC3 DSENC4 DSENC5 DSENC6 DSENC7 ATIS 5V 5V UP DN VCC PTT KEYM KEYM 5V 5V CH16 CH 5V NMEAI 5V VCC HANG BEEPM DIM3 RRXD RTXD DIM3 CONT1 CONT2 OENA 15 IC3 BU4094BCFV PDATA PCK RMUTM PTTM EXSTB S27 DS1 TTR5341 S28 S13 S14 S17 S16 S15 S20 S19 S18 S21 S23 S22 S24 S26 S25 C0 C2 C1 C3 S2 S1 S3 S5 S4 S7 S6 S10 S8 S11 S12 S9 1 2 3 4 7 6 5 10 9 8 11 13 12 1...

Страница 33: ...1 RV 143 Q16 DTC144EU C93 0 001 R74 100 k C94 0 01 C95 22 P C47 0 1 C190 0 001 C189 0 001 DET 5V DET 5V R93 1 M R87 100 k R169 100 k R91 1M R95 1 M C137 0 1 R96 2 7 k Q21 2SC4116 BL R98 470 k C138 0 022 C139 0 022 C141 10 R102 1 k R101 15 k 5V VOL1 VBIAS C136 2 2 R66 3 3 C90 0 01 R69 220 C135 0 01 R99 150 k R100 15 k C140 0 1 R97 390 MMIC TMUTE HI LO TXDET VBIAS 5V VOL1 R73 8 2 k R82 2 7 k C128 0 ...

Страница 34: ...IS UNIT W1 to MAIN unit J4 to LOGIC board J3 PTT MIC UP DN 16 9 MC1 C1 470 P R1 12 k W2 W1 S1 S2 R2 6 8 k S3 R3 15 k R4 33 k S4 PTT MICG MIC GND 1 2 3 4 PTT MICG MIC PTTG KEYM GND 1 2 UP_ON 2 0V DN_ON 3 0V 16 9_ON 3 8V ...

Страница 35: ...8155 Fax 425 454 1509 URL http www icomamerica com Customer Service Phone 425 454 7619 Glenwood Centre 150 6165 Highway 17 Delta B C V4K 5B8 Canada Phone 604 952 4266 Fax 604 952 0090 URL http www icomcanada com A B N 88 006 092 575 290 294 Albert Street Brunswick Victoria 3056 Australia Phone 03 9387 0666 Fax 03 9387 0022 URL http www icom net au 146A Harris Road East Tamaki Auckland New Zealand ...

Страница 36: ...1 1 32 Kamiminami Hirano ku Osaka 547 0003 Japan S 13808IZ C1M 2001 Icom Inc ...

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