Icom IC-T81A Service Manual Download Page 39

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9-2 RF UNIT

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TOP VIEW

9 - 3

C981

C964

C971

C970

C967

L933

C951

C966

C969

L921

Q905

L931

Q912

C170

L142

L123

L801

Q826

D919

L342

Q341

Q904

L304

Q902

D901

L306

Q343

C954

L56

L57

L58

L202

Q202

L205

L59

Q910

D602

L201

L13

Q923

R928

R949

C960

C961

C962

C963

L910

L909

L143

D801

D810

Q819

Q820

Q818

Q931

Q825

Q932

D341

C175

L932

Q913

Q807

L344

Q813

L345

L346

L347

L348

L913

C942

C944

L91

L905

L101

Q901

L305

L802

L64

Q51

L303

D601

L206

Q53

Q602

Q701

L701

D909

C955

C956

C943

D908

C31

C29

C101

R100

C972

C84

C23

C20

C19

C18

C17

C15

C14

C10

C916

C64

C51

C52

C53

R51

C34

C55

C202

R203

R201

C203

C208

C57

C62

C63

C989

C213

R205

C205

C207

R57

C602

R608

R951

R210

C212

C527

C601

C610

R610

C82

C704

C71

C73

R701

C609

C717

C702

R61

R209

C323

R316

R207

R302

C310

C307

R208

C209

C201

R301

C306

R307

R31

C322

R312

C321

R306

R308

C805

C807

C855

C854

R867

R866

C806

C852

R802

R826

C350

R828

C349

C352

R864

C356

C355

C853

C833

C313

C91

R901

C305

C27

C326

C22

R929

C945

C941

C923

R925

R158

C178

C873

C871

R839

C875

R10

C190

C345

R344

R343

C93

C88

C89

C937

C935

C939

C839

C180

C907

C908

R913

C802

C801

C831

C832

C827

R923

C924

R912

C915

C965

L917

L916

Q922

L912

L17

L11

Q201

IC601

FI601

IC51

FI51

J952

J951

R911

L906

Q903

IC801

L920

L15

L919

L907

L908

Q921

Q138

C874

C872

C870

C868

C193

L918

L14

L16

L12

L10

FI52

Q301

L18

C32

C24

C28

C21

C25

C988

R31

C35

C54

R53

R52

R58

R202

C206

R204

C210

C314

C61

R513

R609

R614

C608

R702

C705

C990

C65

C603

C211

R206

C320

R310

R304

C308

C311

C315

R309

C318

R803

R827

C830

R844

R348

R349

C358

C351

C353

C354

R868

C359

C357

R865

C319

R902

C928

R924

R163

C914

C172

R728

C741

C869

C199

C198

C867

R952

C938

C342

C346

C344

C94

C343

C161

C137

C803

R841

C818

C913

R303

C204

C60

C59

C56

C16

C12

C13

C33

R938

R903

C327

C325

R930

R931

R932

C950

C949

C948

C30

D907

D918

D906

D903

D51

D52

D31

D202

D306

D203

D309

D204

D310

D134

D53

D31

D201

D304

L61

IC6

L65

L62

L343

C95

C90

IFIN

GND

PSET

GND

+3C

PDA2/UL

VCC

LOCKV

PLST1

PDA1/UL

BDET

GND

MOD

GND

PLST2

FSET

EURDEV

2NDLO

GND

THERM

IOST

ATA

AGC

TUNE

VHVCO

UVCO

TXC

12VCO

WFM

GND

R+3

CHGC

6MVCO

GND

DC-DC

J4 to LOGIC unit J1

Summary of Contents for IC-T81A

Page 1: ...SERVICE MANUAL MULTIBAND FM TRANSCEIVER...

Page 2: ...ZK IC T81A E Chassis 10 pieces Addresses are provided on the inside back cover for your convenience 1 Make sure a problem is internal before disassembling the transceiver 2 DO NOT open the transceiver...

Page 3: ...4 5 4 5 PORT ALLOCATIONS 4 6 SECTION 5 ADJUSTMENT PROCEDURES 5 1 PREPARATION 5 1 5 2 PLL ADJUSTMENT 5 2 5 3 RECEIVER ADJUSTMENT 5 4 5 4 TRANSMITTER ADJUSTMENT 5 8 SECTION 6 PARTS LIST SECTION 7 MECHA...

Page 4: ...ht with BP 197 Ant 290 g 10 2 oz M TRANSMITTER Output power at 13 5 V DC High 5 0 W typical 1 0 W at 1200 MHz band Low 1 0 W typical 0 1 W at 1200 MHz band Modulation system Variable reactance modulat...

Page 5: ...d AM 50 MHz only Less than 0 56 V Threshold WFM Less than 5 6 V Threshold Selectivity except WFM More than 15 kHz 6 dB Less than 30 kHz 60 dB Spurious and image rejection ratio 50 144 MHz More than 60...

Page 6: ...1 TA7368F AF volume IC202 M5222FP AF mute switch Q361 2SJ364 CPU IC1 M38267M8LGP BOTTOM VIEW VCO circuit 1st mixer IC601 PC2757T WFM RF amplifier circuit APC sensor drive amplifier Q911 UN9215 Q913 XP...

Page 7: ...E LOGIC UNIT 1 Remove the sealing rubber 2 Unsolder 1 point D to separate a SENSOR control 3 Unscrew 3 screws E 4 Unplug J1 to separate LOGIC unit and RF unit 5 Remove the LOGIC unit in the direction...

Page 8: ...MHz Thus transmit signals are blocked from entering the receiv er circuits The antenna switching circuit employs a 1 4 type diode switching system The passed signals are then applied to each RF ampli...

Page 9: ...components The filtered 1st IF signal is applied to the IF amplifier IC701 The amplified signal is applied to the 2nd mixer circuit LOGIC unit IC701 pin 16 WFM band The RF signals are mixed with 1st L...

Page 10: ...e filter section amplifies and filters noise components The filtered signals are applied to the noise detector section and output from IC701 pin 13 as NOISE signal The NOISE signal from IC701 pin 13 i...

Page 11: ...and is then amplified at the power amplifier Q922 to obtain 5 0 W of RF power The amplified signal is passed through the antenna switch ing circuit D101 and D102 low pass filters and high pass filters...

Page 12: ...signal at the 440 VCO circuit VCO unit Q321 Q322 D321 and Q322 is amplified at the buffer amplifiers VCO unit Q323 The amplified signal is applied to the PLL IC IC801 pin 19 via a buffer amplifier Q8...

Page 13: ...tter circuit Buff Q816 Pin Port Description number name 4 5 6 7 11 12 13 14 Q1 Q2 Q3 Q4 Q8 Q7 Q6 Q5 Outputs VHVCO3 regulator control signal Outputs VLVCO3 regulator control signal Outputs 6MVCO3 regul...

Page 14: ...strobe signals to the PLL IC2 RF unit IC802 pin5 Outputs strobe signals to the PLL IC1 RF unit IC801 pin 3 Output port for the cloning signal 20 21 22 23 24 25 26 27 28 29 30 31 32 33 39 41 42 43 46...

Page 15: ...QUIPMENT DC power supply RF power meter terminated type Frequency counter FM deviation meter GRADE AND RANGE Output voltage 13 5 V DC Current capacity 3 A or more Measuring range 1 10 W Frequency rang...

Page 16: ...MHz USA 1 only 435 000 MHz ohter Connect an SSG to the antenna connector and set as Level 1 mV 47dBm Modulation OFF Receiving RF Top Pannel LOGIC Connect the DC voltmeter or an oscilloscope to VLV Con...

Page 17: ...ULV PLL lock voltage check point for 440 MHz PLL lock voltage check point for 1200 MHz RF UNIT BOTTOM VIEW 6MLV PLL lock voltage check point for 50 MHz TX RF UNIT TOP VIEW L702 Detector Output voltag...

Page 18: ...z Modulation 1 kHz Receiving Displayed frequency 107 000 MHz Receiving Displayed frequency 108 000 MHz Set an SSG as Frequency 108 000 MHz Level 1 0 V AM 107 dBm Modulation 1 kHz Mod depth 30 Receivin...

Page 19: ...5 5 LOGIC UNIT TOP VIEW 50 MHz WFM BAND AIR BAND and 145 MHz Sensitivity check point SD...

Page 20: ...layed frequency 92 000 MHz SEA USA 1 98 000 MHz EUR UK ITA AUS Connect the SSG to the antenna connector and set as Level 2 V 101 dBm Modulation 1 kHz Deviation 52 5 kHz Connect a terminator to the SP...

Page 21: ...level for the S meter to S3 Receiving Increase an SSG output level Receiving Displayed frequency 445 000 MHz USA 1 435 000 MHz other Connect the SSG to the antenna connector and set as Level 0 1 V 12...

Page 22: ...cy 1270 000 MHz Output power High Transmitting Output power Low Transmitting Top panel Top panel Top panel Top panel Connect an RF power meter to the antenna connector Connect an RF power meter to the...

Page 23: ...ransmitting Displayed frequency 445 000 MHz USA 1 only 435 000 MHz AUS SEA only Push D key while transmitting Transmitting Displayed frequency 435 000 MHz Push center of the multi func tion key while...

Page 24: ...GEJ 103 X 10 k R9 7030005110 S RESISTOR ERJ2GEJ 224 X 220 k R10 7030005220 S RESISTOR ERJ2GEJ 223 X 22 k R12 7030005840 S RESISTOR RR0510R 473 D 47 k R13 7030005840 S RESISTOR RR0510R 473 D 47 k R14 7...

Page 25: ...J 103 X 10 k R752 7030005230 S RESISTOR ERJ2GEJ 334 X 330 k R753 7030005000 S RESISTOR ERJ2GEJ 471 X 470 R754 7030005240 S RESISTOR ERJ2GEJ 473 X 47 k R755 7030005120 S RESISTOR ERJ2GEJ 102 X 1 k R756...

Page 26: ...102KBQ C927 4030013850 S CERAMIC ECUE1E102KBQ J1 6510019860 S CONNECTOR AXK6S40645P J3 6450002010 S CONNECTOR HSJ1501 011010 J4 6450001680 CONNECTOR HSJ1122 010010 DS1 5040002230 S LED CL 200YG C TS D...

Page 27: ...50000360 S DIODE 1SS364 TE85L D721 1750000360 S DIODE 1SS364 TE85L D801 1790000850 S DIODE MA132WK TX D802 1790001260 S DIODE MA2S077 TX D803 1790001260 S DIODE MA2S077 TX D804 1790001260 S DIODE MA2S...

Page 28: ...X 6 8 k R52 7030005040 S RESISTOR ERJ2GEJ 472 X 4 7 k R53 7030005570 S RESISTOR ERJ2GEJ 820 X 82 R57 7030005120 S RESISTOR ERJ2GEJ 102 X 1 k R58 7030007270 S RESISTOR ERJ2GEJ 151 X 150 R100 7030005090...

Page 29: ...RESISTOR ERJ2GEJ 103 X 10 k R855 7030005290 S RESISTOR ERJ2GEJ 682 X 6 8 k R857 7030008370 S RESISTOR ERJ2GEJ 561 X 560 R862 7030005290 S RESISTOR ERJ2GEJ 682 X 6 8 k R864 7030004980 S RESISTOR ERJ2G...

Page 30: ...50 S CERAMIC ECUE1E102KBQ C120 4030016820 S CERAMIC ECUE1HR75BCQ C121 4030013850 S CERAMIC ECUE1E102KBQ C123 4030014120 S CERAMIC ECUE1H100CCQ C124 4030013850 S CERAMIC ECUE1E102KBQ C131 4030013850 S...

Page 31: ...7 4030014280 S CERAMIC ECUE1H0R3BCQ C728 4030014100 S CERAMIC ECUE1H070CCQ C729 4030014020 S CERAMIC ECUE1H020BCQ C730 4030009820 S CERAMIC C1005 JB 1C 103K T A C731 4030009820 S CERAMIC C1005 JB 1C 1...

Page 32: ...CUE1E102KBQ C976 4030013850 S CERAMIC ECUE1E102KBQ C977 4030013850 S CERAMIC ECUE1E102KBQ C978 4030013850 S CERAMIC ECUE1E102KBQ C979 4030013850 S CERAMIC ECUE1E102KBQ C980 4030013850 S CERAMIC ECUE1E...

Page 33: ...KBQ C316 4030014280 S CERAMIC ECUE1H0R3BCQ C317 4030013850 S CERAMIC ECUE1E102KBQ C318 4030013850 S CERAMIC ECUE1E102KBQ C319 4030013850 S CERAMIC ECUE1E102KBQ C320 4030013850 S CERAMIC ECUE1E102KBQ C...

Page 34: ...EUR UK ITA 1 MP25 8930044470 1903 DC cap 1 MP26 8930044480 1903 Lens 1 MP28 8810008990 Screw PH BT M2x10 ZX 2 MP29 8810009510 Screw FH BT M2x4 NI ZU 11 MP30 8810009630 Screw FH No 0 M2x4 5 NI B 2 MP3...

Page 35: ...P1 C LOGIC unit VCO unit RF unit MP3 C MP18 C MP29 C MP9 C SP1 C MP22 C EP2 L MP25 C MP26 C MP6 C MP2 L MP29 C DS4 L MP1 L S1 C MP30 C J1 C MP21 C MP28 C MP2 C MP20 C MP17 C MP2 RF MP1 V MP31 C MP13 C...

Page 36: ...8A B E C UN9210 Symbol 8L B E C UN9211 Symbol 8A B E C B E C B E C UN9215 Symbol 8E UN921E Symbol 8N B E C XP1115 Symbol 9L XP1116 Symbol 7N XP1501 AB Symbol 5R B1 E B2 C1 C2 B1 E B2 C1 C2 B1 E B2 C1...

Page 37: ...3 R154 R305 R322 R18 R19 C321 R329 C322 R330 C328 R339 C320 R328 C326 R15 C77 C901 IC5 IC2 S7 DS3 R901 C927 C926 C751 C758 C754 Q754 C757 C241 C240 Q752 Q603 Q602 R752 R718 R730 R736 R735 C713 R734 R7...

Page 38: ...C252 C216 D304 Q361 Q303 Q302 C316 C317 C718 Q753 C306 C311 C904 C903 L2 FI701 S401 S402 C147 IC4 X1 J3 C142 C149 R301 R306 R307 R309 R918 R39 R2 R144 C148 C923 C141 C150 C917 R24 R38 R23 R32 R27 R28...

Page 39: ...5 C941 C923 R925 R158 C178 C873 C871 R839 C875 R10 C190 C345 R344 R343 R4 C93 R2 C88 C89 C937 C935 C939 C839 C180 C907 C908 R913 C802 C801 C831 C832 C827 R923 C924 R912 C915 C965 L917 L916 Q922 L912 L...

Page 40: ...51 R125 R124 R126 C135 R909 R908 C120 C121 C119 R110 C117 C114 R133 R414 C139 R895 C895 R894 C524 C521 C417 C900 R512 R615 R612 C991 C992 C 5 1 9 R870 R854 C816 R807 R869 R726 C731 R721 C726 R725 C192...

Page 41: ...322 C370 Q350 L330 L360 D351 L322 D322 L312 L302 Q301 Q302 L311 Q312 D312 L331 C389 C361 R369 R364 C365 C364 C363 R360 C322 D321 C321 C333 R301 R302 C302 C334 D302 D301 C304 R306 C323 C371 R324 C324 R...

Page 42: ...9 6 BOTTOM VIEW C388 R374 Q354 Q353 L333 L337 L336 R371 C380 C378 C381 C384 R373 L338 L335 L334 C375 C376 R372 C387 R321 C386 C385 C383 C303 C382 C379 C377...

Page 43: ...SW 430MHz BAND SW 144MHz Q306 2SJ364 Q305 2SJ364 Q304 2SJ364 DEV SW Q307 UN9214 BAMD SW 1200MHz REG 3C DC DC DATA CK DAST AF FILTER IC241 NJM2902V VOL Q751 XP1501 Q752 2SD2216 Q754 2SD2216 IC5 M62368...

Page 44: ...901 NJM3404AV PSET RX Lo FREQUENCY 50MHz BAND WFM BAND 144MHz BAND 430MHz BAND 1200MHz BAND Q301 3SK291 D309 MA2SV05 D310 MA2SV05 Q201 3SK292 D203 MA2S304 D306 MA2SV05 D202 MA2S304 RX FREQUENCY WFM BA...

Page 45: ...2SC4228 IC802 TB31242FN COMMON RX BUS 3C IC5 S 81332HG KC Q1 2SD2216 Q2 XP1501 Q3 2SB1132 T4 REG 3 TXC Q901 UN9211 Q902 2SD2216 Q903 2SB1132 D901 MA133 I O DC SW CHG VCC TO BATT DATA IC3 BU4094BCFV Q...

Page 46: ...1 K R248 470K C245 0 1 R246 120K C246 0 1 C247 100 P R247 100 K C243 0 1 R142 22 K C756 0 01 VCC VIN C718 0 1 R757 22 K R758 47 K C755 0 047 R760 1 M D I G C145 0 001 D143 MA2S111 R145 10 K C151 0 00...

Page 47: ...13 0 001 C720 0 047 R734 22 K C735 0 1 R733 20 K C736 0 001 SD NOISE L702 LS 528 Q702 UN9115 R729 1 8 K PSET 8 IC4 TC4W53FU C907 0 001 R1 NTCCF20124AH 473KCT TXC 5 6 7 4 3 2 1 C906 0 001 J1 AXK6S40645...

Page 48: ...20 0 1 C241 0 1 R241 1 M R244 82 K R243 82 K R242 470 K C242 0 039 R249 220 K C244 0 1 R245 82 K C240 0 0015 1 2 3 4 5 6 7 14 13 12 11 10 9 8 IC241 NJM2902V C252 0 0022 C251 0 001 R253 56K R254 56 K R...

Page 49: ...H Q341 2SC4215 O C347 0 01 C344 0 001 C348 3 P R351 15 R839 15 R867 220 Q813 2SC5107 O C854 0 001 C852 0 001 C833 0 001 R828 220 D810 MA6S121 C832 0 001 C831 0 001 L802 4 7 H C748 0 001 R726 4 7 K R72...

Page 50: ...4 0 001 C71 0 001 C213 0 001 C82 0 001 C70 0 001 Q202 UN9115 C197 0 001 C304 0 001 C513 0 001 D52 MA2S077 D51 MA2S077 C73 0 001 C141 0 001 C171 0 001 C180 0 001 R158 3 9 K C901 0 001 R919 4 7 K C912 2...

Page 51: ...001 R3 4 7 K C94 0 001 C875 0 001 C873 0 001 C871 0 001 C869 0 001 C867 0 001 C726 7 P C895 0 001 R895 33 K C894 0 001 C897 6 P R892 4 7 K D805 MA2S077 L809 22 nH R889 220 C888 0 001 C889 0 001 C882 0...

Page 52: ...ne 425 454 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 h...

Page 53: ...1 1 32 Kamiminami Hirano ku Osaka 547 0003 Japan A 5566I S 1 1999 Icom Inc...

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