SERVICE MANUAL MULTIBAND FM TRANSCEIVER
INTRODUCTION This service manual describes the latest service information for the IC-T81A/E at the time of publication. MODEL VERSION U.S.A. Australia S.E.Asia Europe U.K. Italy IC-T81A IC-T81E SYMBOL USA-1 AUS SEA EUR UK ITA To upgrade quality, all electrical or mechanical parts and internal circuits are subject to change without notice or obligation. DANGER NEVER connect the transceiver to an AC outlet or to a DC power supply that uses more than 16 V.
TABLE OF CONTENTS SECTION 1 SPECIFICATIONS SECTION 2 INSIDE VIEWS SECTION 3 DISASSEMBLY INSTRUCTIONS SECTION 4 CIRCUIT DESCRIPTION SECTION 4-1 RECEIVER CIRCUITS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-1 4-2 TRANSMITTER CIRCUITS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-3 4-3 PLL CIRCUITS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
SECTION 1 M SPECIFICATIONS GENERAL • Frequency range : Version 145 MHz 440 MHz TX: 144 – 148 TX: 430 – 450*3 50 MHz U.S.A. 50 – 53.995 Australia 50 – 53.995 S.E.Asia 50 – 53.995 Europe, U.K. 50 – 52 1200 MHz 91.5 MHz (RX only) 1240 – 1300 76 – 107.995*4 430 – 440 1240 – 1300 88 – 107.995*4 400 – 469.995*2 1240 – 1300 76 – 107.995*4 430 – 440 1240 – 1300 88 – 107.995*4 400 – 469.995*2 1240 – 1300 88 – 107.995*4 RX: 118 – 173.995*1 RX: 400 – 469.995*3 144 – 148 TX: 136 – 173.
M RECEIVER • Receiver system : Double-conversion superheterodyne • Intermediate frequency : 1st 69.45 MHz (13.35 MHz: WFM) 2nd 450 kHz • Sensitivity* : (except spurious points; typical values) Band FM AM WFM 50 MHz 0.18 µV 0.56 µV – 144 MHz 0.18 µV – – 440 MHz 0.18 µV – – 1200 MHz 0.25 µV – – – – 2.0 µV 91.5 MHz * FM and WFM are measured at 12 dB SINAD, AM is measured at 10 dB S/N.
SECTION 2 INSIDE VIEWS • LOGIC UNIT BOTTOM VIEW Crystal filter (X1: CR-639 5.
SECTION 3 DISASSEMBLY INSTRUCTIONS • REMOVING THE CHASSIS PANEL • REMOVING THE SHIELD PLATE 1 Remove 1 knob A, and unscrew 1 nut B. 2 Unscrew 2 screws C. 3 Remove the chassis panel in the direction of the arrow. 1 Unsolder 10 points, F, to separate the shield plate and LOGIC unit. F B Chassis panel Shield plate C A F F LOGIC unit • REMOVING THE LOGIC UNIT • REMOVING THE RF UNIT 1 2 3 4 5 1 Unsolder 1 point, G, to separate [ANT] plug. 2 Unscrew 8 screws, H, to separate the RF unit.
SECTION 4 CIRCUIT DESCRIPTION Thus, transmit signals are blocked from entering the receiver circuits. The antenna switching circuit employs a 1/4λ type diode switching system. The passed signals are then applied to each RF amplifier circuit. 4-1 RECEIVER CIRCUITS 4-1-1 DUPLEXER CIRCUIT (RF UNIT) The transceiver has a duplexer (low-pass and high-pass filters) on the frist stage from the antenna connector to separate the signals into below UHF and SHF signals.
• 50, 144, 440 and 1200 MHz band The applied RF signals are mixed with 1st LO signals at the 1st mixer (IC601) to produce a 69.45 MHz 1st IF signal. The 1st IF signal is output from the 1st mixer (IC601, pin 6), and then passed through the crystal bandpass filter (FI601) to suppress unwanted harmonic 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).
Even when the squelch is closed, the AF mute switch (Q361) opens at the moment of emitting beep tones. 4-1-8 2ND IF AND DEMODULATOR CIRCUITS (RF AND LOGIC UNITS) The 2nd mixer circuit converts the 1st IF signal to the 2nd IF signal. A double conversion superheterodyne system (which converts receive signals twice) improves the image rejection ratio and obtain stable receiver gain.
The amplified signal is passed through the antenna switching circuit (D101 and D102), low-pass filters and high-pass filters. The signal is applied to the antenna connector. (3) 440 MHz band The signals from the limiter amplifier (RF unit; IC301) changes the reactance of a diode (VCO unit; D321) to modulate the oscillated signal at the 440-VCO circuit (VCO unit; Q321, Q322, D321, D322, L322). The modulated signals are amplified at the buffer-amplifier (Q323) and the LO amplifier (Q823).
The applied signal is divided by serial data from the CPU (Ndata) and phase-detected with the divided reference frequency (5 kHz) at the phase detector section in the PLL IC. The phase-detected signal is output from IC801 (pin 13) and converted DC voltage at the active filter (Q811, Q812). The converted DC voltage is fed back to the VCO board as the “VLV” signal of the lock voltage.
4-5 PORT ALLOCATIONS 4-5-2 I/O EXPANDER IC (RF UNIT; IC3) 4-5-1 I/O EXPANDER IC (RF UNIT; IC2) Pin Port number name Pin Port number name Description Description 4 Q1 Outputs VHVCO3 regulator control signal. 4 Q1 Outputs 300 MHz band RX regulator control signal. 5 Q2 Outputs VLVCO3 regulator control signal. 6 Q3 Outputs AM mode regulator control signal. 6 Q3 Outputs 6MVCO3 regulator control signal. 7 Q4 Outputs WFM band RX switching control signal.
4-5-3 CPU (LOGIC UNIT; IC1) Pin Port number name 1 2 VIN Input port for the over-voltage detection from connected battery pack or external power supply. Input port for remote control signals REMOTE from an optional HM-75A microphone via the [MIC] jack. 3 SD 4 CTCIN 5 Pin Port Description number name 20 CLONEIN Input port for the cloning signal. Description LOCKV Input port for the S-meter voltage. Input port for CTCSS decoded signals. 21 TXC Outputs T4 regulator control signal.
SECTION 5 ADJUSTMENT PROCEDURES 5-1 PREPARATION ‘ REQUIRED TEST EQUIPMENT EQUIPMENT GRADE AND RANGE Output voltage Current capacity : 13.5 V DC : 3 A or more RF power meter (terminated type) Measuring range Frequency range Impedance SWR : : : : Frequency counter Frequency range : 0.1–1500 MHz Frequency accuracy : ±1 ppm or better Sensitivity : 100 mV or better FM deviation meter Frequency range Measuring range DC power supply 1–10 W 28–1500 MHz 50 Ω Less than 1.
5-2 PLL ADJUSTMENT The following adjustment must be performed at “ADJUSTMENT MODE”. ADJUSTMENT MEASUREMENT ADJUSTMENT CONDITION UNIT PLL LOCK VOLTAGE 1 • Displayed frequency : 51.000 MHz • Receiving RF UNIT Connect the DC 1.8 V – 2.8 V voltmeter or an oscilloscope to 6MLV. 3 • Displayed frequency : 88.000 MHz • Receiving Connect the DC 1.4 V – 2.4 V voltmeter or an oscilloscope to VLV. 4 • Displayed frequency : 145.000 MHz • Receiving 1.5 V – 2.5 V 5 • Transmitting 1.5 V – 2.
• RF UNIT BOTTOM VIEW 12LV PLL lock voltage check point (for 1200 MHz) ULV PLL lock voltage check point (for 440 MHz) VLV PLL lock voltage check point (for 50 MHz RX, WFM and 144 MHz) • RF UNIT TOP VIEW 6MLV PLL lock voltage check point (for 50 MHz TX) • LOGIC UNIT TOP VIEW L702 Detector Output voltage adjustment Q Detector Output voltage check point 5-3
5-3 RECEIVER ADJUSTMENT The following adjustment must be performed at “ADJUSTMENT MODE”. ADJUSTMENT ADJUSTMENT CONDITION MEASUREMENT UNIT VALUE LOCATION ADJUSTMENT POINT UNIT ADJUST Top panel [DIAL] LOGIC Connect a multime- Maximum voltage ter to check point SD. Top panel [DIAL] LOGIC Connect a multime- Maximum voltage ter to check point SD. Top panel [DIAL] LOGIC Connect a multime- Maximum voltage ter to check point SD.
• LOGIC UNIT TOP VIEW SD 50 MHz, WFM BAND, AIR BAND and 145 MHz Sensitivity check point 5-5
RECEIVER ADJUSTMENT (Continued) The following adjustment must be performed on the normal mode after “SENSITIVITY ADJUSTMENT” in SECTION 5-3. ADJUSTMENT ADJUSTMENT CONDITION MEASUREMENT UNIT 1 • Displayed frequency : S-METER 51.000 MHz [EUR], [UK], [ITA] (50 MHz band) 52.000 MHz [AUS], [SEA], [USA-1] • Connect the SSG to the antenna connector and set as: Level : 1 µV* (– 107 dBm) Modulation : 1 kHz Deviation : ± 3.5 kHz • Connect a terminator to the [SP] jack.
RECEIVER ADJUSTMENT (Continued) The SQUELCH LEVEL adjustment must be performed on the normal mode after “S-METER ADJUSTMENT”. ADJUSTMENT ADJUSTMENT CONDITION MEASUREMENT UNIT 9 S-METER (440 MHz band) • Displayed frequency : 445.000 MHz [USA-1] 435.000 MHz [other] • Connect the SSG to the antenna connector and set as: Level : 0.63 µV* (– 111 dBm) Modulation : 1 kHz Deviation : ± 3.5 kHz • Connect a terminator to the [SP] jack.
5-4 TRANSMITTER ADJUSTMENT The following adjustment must be performed at “ADJUSTMENT MODE”. ADJUSTMENT ADJUSTMENT CONDITION MEASUREMENT UNIT OUTPUT POWER (50 MHz) 1 • Displayed frequency : 51.000 MHz [EUR], [UK], [ITA] 52.000 MHz [AUS], [SEA], [USA-1] • Output power : High • transmitting 2 • Output power • Transmitting (144 MHz) (440 MHz) (1200 MHz) 8 • Output power • Transmitting Top panel Connect an RF more than 5 W power meter to the antenna connector. [DIAL] [DIAL] 0.
TRANSMITTER ADJUSTMENT (Continued) The following adjustment must be performed after “REFERENCE FREQUENCY ADJUSTMENT” in SECTION 5-2. ADJUSTMENT ADJUSTMENT CONDITION MEASUREMENT UNIT VALUE LOCATION ADJUSTMENT POINT UNIT ADJUST LOGIC R327 FM DEVIATION (50 MHz) 1 • Displayed frequency : 51.000 MHz [EUR], [UK], [ITA] 52.000 MHz [AUS], [SEA], [USA-1] • Connect the audio generator to the [MIC] connector and set as: 95 mV/1.0 kHz.
SECTION 6 PARTS LIST [LOGIC UNIT] REF NO. IC1 [LOGIC UNIT] ORDER NO. REF NO. DESCRIPTION IC2 IC3 IC4 IC5 IC141 IC142 IC201 IC202 IC203 IC241 IC301 IC701 IC751 1140008110 1140008100 1130009160 1110004890 1130006220 1110004530 1180001720 1110004540 1110001810 1110004520 1110002750 1110003780 1110004110 1110003490 1130004200 S.IC S.IC S.IC S.IC S.IC S.IC S.IC S.IC S.IC S.IC S.IC S.IC S.IC S.IC S.IC M38267E8GP [USA-1] only M38267M8L-230GP [other] X24320S8I-2.
[LOGIC UNIT] REF NO. R245 R246 R247 R248 R249 R250 R251 R252 R253 R254 R267 R301 R302 R303 R304 R305 R306 R307 R308 R309 R310 R311 R312 R313 R314 R315 R316 R317 R318 R319 R320 R321 R322 R323 R324 R325 R326 R327 R328 R329 R330 R331 R332 R333 R334 R335 R336 R337 R338 R339 R340 R341 R342 R343 R361 R362 R363 R706 R713 R714 R715 R716 R717 R718 R719 R726 R727 R729 R730 R731 R732 R733 R734 R735 R736 R737 R751 R752 R753 R754 R755 R756 [LOGIC UNIT] ORDER NO.
[LOGIC UNIT] REF NO. [LOGIC UNIT] ORDER NO. REF NO.
[RF UNIT] REF NO. [RF UNIT] ORDER NO. REF NO. DESCRIPTION ORDER NO.
[RF UNIT] REF NO. L143 L201 L202 L205 L206 L301 L302 L303 L304 L305 L306 L341 L342 L343 L344 L345 L346 L347 L348 L401 L402 L403 L404 L501 L502 L503 L504 L505 L507 L701 L721 L723 L724 L725 L726 L801 L802 L804 L806 L807 L808 L809 L810 L811 L905 L906 L907 L908 L909 L910 L911 L912 L913 [RF UNIT] ORDER NO. REF NO.
[RF UNIT] REF NO. R351 R401 R402 R403 R404 R409 R410 R413 R414 R501 R502 R503 R504 R505 R506 R507 R508 R509 R510 R511 R512 R513 R608 R609 R610 R611 R612 R613 R614 R615 R616 R701 R702 R721 R722 R725 R726 R727 R728 R742 R802 R803 R804 R805 R806 R807 R811 R812 R813 R814 R815 R816 R817 R818 R819 R820 R821 R826 R827 R828 R829 R838 R839 R841 R842 R844 R845 R847 [RF UNIT] ORDER NO.
[RF UNIT] REF NO. C6 C7 C8 C9 C10 C12 C13 C14 C15 C16 C17 C18 C19 C20 C21 C22 C23 C24 C25 C27 C28 C29 C30 C31 C32 C33 C34 C35 C36 C37 C41 C42 C43 C44 C45 C46 C48 C49 C50 C51 C52 C53 C54 C55 C56 C57 C58 C59 C60 C61 C62 C63 C64 C65 C70 C71 C72 C73 C78 C82 C84 C85 C86 C87 C88 C89 C90 C91 C92 C93 C94 C95 C101 C102 C103 C107 C108 C114 C115 C116 C117 C119 [RF UNIT] ORDER NO.
[RF UNIT] REF NO. C321 C322 C323 C324 C325 C326 C327 C341 C342 C343 C344 C345 C346 C347 C348 C349 C350 C351 C352 C353 C354 C355 C356 C357 C358 C359 C401 C402 C403 C404 C405 C409 C410 C411 C412 C413 C415 C416 C417 C418 C502 C503 C504 C505 C506 C507 C508 C509 C510 C511 C512 C513 C514 C515 C516 C517 C518 C519 C521 C522 C523 C524 C525 C526 C527 C601 C602 C603 C608 C609 C610 C612 C613 C702 C704 C705 C717 C722 C724 C725 C726 C727 [RF UNIT] ORDER NO.
[RF UNIT] REF NO. [RF UNIT] ORDER NO. C895 C896 C897 C898 C899 C900 4030013850 4030014050 4030014090 4030013850 4030013850 4030014020 S.CERAMIC S.CERAMIC S.CERAMIC S.CERAMIC S.CERAMIC S.
[VCO BOARD] REF NO. [VCO BOARD] ORDER NO. REF NO.
SECTION 7 MECHANICAL PARTS AND DISASSEMBLY [VCO UNIT] [CHASSIS PARTS] REF. NO. ODER NO.
MP13 (C) MP30 (C) MP10 (C) MP24 (C) J1 (C) MP21 (C) MP31 (C) S1 (C) RF unit MP1 (RF) MP28 (C) MP29 (C) MP6 (L) MP29 (C) MP9 (L) MP29 (C) MP14 (C) MP17 (C) MP4 (L) DS4 (L) MP19 (C) MP5 (L) MP2 (L) MP1 (L) MP2 (C) MP20 (C) MP6 (C) MP2 (RF) MP26 (C) MP1 (V) MP29 (C) MP23 (C) LOGIC unit MP32 (C) SP1 (C) EP2 (L) MP9 (C) MP18 (C) MP7 (C) MP22 (C) MP3 (C) MP1 (C) MP25 (C) UNIT abbreviation (C): CHASSIS PARTS, (L): LOGIC UNIT (RF): RF UNIT, (V): VCO UNIT 7-2 MP29 (C) VCO unit
SECTION 8 SEMI-CONDUCTOR INFORMATION • TRANSISTOR AND FET’S 2SA1588 GR (Symbol: ZG) • DIODES 2SB1132 R (Symbol: BARB) 2SB1201 S (Symbol: B1201) C C 2SC3356 R25 (Symbol: R25) B B C E 1SS364 (Symbol: BF) 1SV270 (Symbol: TF) 1SV271 (Symbol: TG) 1SV282 (Symbol: TD) 1SV288 (Symbol: TJ) pink B B 2SB1462 R (Symbol: BR) C E C E E 2SC4228 R45 (Symbol: R45) 2SC4403 3 (Symbol: LY3) B E 2SC4117 BL (Symbol: CL) 2SC4215 0 (Symbol: QO) B 2SC4226 R25 (Symbol: R25) B C B B C E E 2SC5006
SECTION 9 BOARD LAYOUTS 9-1 LOGIC UNIT TOP VIEW D58 DS1 D52 C926 R35 IC203 D59 D61 D57 D51 D56 D54 D55 D53 D141 R214 R213 R151 C103 Q141 R29 R141 C102 C322 C328 C320 C240 R244 R243 R339 R245 C244 R330 MC1 Q306 IC241 C247 C245 Q305 R246 C242 R337 R331 R323 R332 R305 IC5 R247 C321 R329 Q309 R322 R248 Q304 R340 R321 D152 C77 R325 R338 R327 R326 Q341 D151 R154 R15 C901 R241 R328 C241 C326 R242 R757 C755 C756 C757 R18 R758 R759 R760 R19 Q7
L1 IC3 21 20 C913 C910 J1 to RF unit J4 20 1 C707 C706 R714 R306 C301 C715 Q301 R727 R301 R309 R5 X1 D144 C141 C145 C142 IC142 C912 C909 40 1 9-2 Q145 R39 C3 IC301 43 C152 R1 R312 J3 6 R1 4 R26 C90 R8 R28 IC1 J4 R16 C9 C220 R206 C204 C91 C92 C93 R37 R25 R56 R55 R54 R31 C143 C148 R145 C308 C151 C150 R51 C12 Q307 R53 C13 C211 R333 R341 R30 R22 R21 IC202 D143 C309 R324 R314 C317 R317 R316 C323 C75 C146 R267 C149 R336 Q302 C316 C324
9-3 IFIN GND PSET GND +3C PDA2/UL VCC VCC LOCKV PLST1 PDA1/UL BDET GND MOD GND PLST2 HV HV FSET EURDEV 2NDLO GND THERM IOST DATA CK AGC TUNE VHVCO UVCO TXC 12VCO WFM AM GND R+3 CHGC 6MVCO GND DC-DC R52 FI601 C56 C54 C608 C351 C990 D602 C603 R614 C705 40 1 L65 J4 J4 to LOGIC unit J1 21 20 C839 Q825 C827 C832 C831 C938 C346 C353 C354 R702 R1 IC6 R3 C94 D341 L343 C833 Q807 C190 C939 Q932 C935 Q931 C937 C801 C802 C915 Q913 L801 L342 Q341 C345 R826 R828 R912 L932 C9
C150 L135 R128 D132 Q139 R944 R936 C968 C904 C977 C982 C3 C181 C975 C183 L922 C902 C41 C58 C44 9-4 C42 L54 D914 R32 C46 C1 R33 C504 C36 D32 C513 L501 R506 C509 L505 R503 C511 R505 C503 D505 C49 C45 L55 C48 Q501 C50 C2 C505 C514 C43 C37 C182 C973 C502 L2 L502 C506 L503 C507 L504 R509 D503 R507 R504 C515 IC501 C517 R510 C978 L925 D913 R502 R501 L3 C516 C986 Q926 C985 D904 R943 R403 D5 R508 C512 D12 R615 C983 01 R413 C412 L926
9-3 VCO BOARD TOP VIEW D312 C330 R303 C318 C320 R316 Q302 R304 C309 Q312 R308 D311 R302 C302 R301 C306 Q301 Q311 C305 R305 R314 C314 Q321 C313 R306 C334 C304 C333 C322 L313 L321 1 9-5 L311 J301 7 D301 L302 C323 D302 C311 D351 D321 C321 C364 C363 R317 R311 R318 C332 C331 C326 R322 R329 C327 L322 C315 C307 R313 L312 C370 C367 Q350 C360 R362 C317 R360 D352 VLV GND ULV MOD SHIFT GND 12LV 1 R307 R315 L360 J301 to RF unit 7 C365 C324 C362 R364 R3
C303 9-6 L336 C377 C384 L334 L337 C379 C387 L333 C380 C376 Q353 R372 L338 R373 C375 R374 L335 R321 C386 Q354 C382 C383 C385 • BOTTOM VIEW C388 R371 C381 C378
SECTION 10 BLOCK DIAGRAM LOGIC UNIT RF UNIT PSET MOD MOD VCO BOARD Q350: 2SC5006 D351: 1SV270 D352: MA2S077 BAND SW 50MHz DC-DC DC-DC +5V Q306: 2SJ364 Q351: 2SC5195 FSET Q307: UN9214 HPF LPF BUFF Q824: 2SC5195 D806: MA2S077 D807: MA2S077 Q131: 2SC5195 LO AMP TX/RX SW BUFF Q354: 2SC5195 Q353: 2SC5195 Q321: 2SC5195 Q322: 2SC5195 D321: MA2S077 D322: HVU350 TUNE DEV SW x2 BUFF BUFF Q823: 2SC5107 D804: MA2S077 D805: MA2S077 LO AMP TX/RX SW FI701: PBFC450R15DR Q304: 2SJ364 IC5:
RF UNIT TX/RX FREQUENCY Q824: 2SC5195 D806: MA2S077 D807: MA2S077 Q131: 2SC5195 LO AMP TX/RX SW BUFF Q823: 2SC5107 D804: MA2S077 D805: MA2S077 LO AMP TX/RX SW Q136: 2SC3356 Q135: 2SC5107 RX-Lo FREQUENCY: 430MHz BAND D802: MA2S077 D803: MA2S077 LO AMP TX/RX SW ANT SW HPF LPF HPF HPF LPF TX-Lo FREQUENCY: 1200MHz BAND TX FREQUENCY: 430MHz BAND Q922: 2SK3075 YGR AMP BUFF Q822: 2SC5107 TX FREQUENCY: 1200MHz BAND YGR AMP BUFF RX-Lo FREQUENCY: 1200MHz BAND D51: MA2S077 D52: MA2S077
SECTION 10 BLOCK DIAGRAM LOGIC UNIT RF UNIT PSET MOD TX/RX FREQUENCY MOD VCO BOARD Q350: 2SC5006 D351: 1SV270 D352: MA2S077 BAND SW 50MHz DC-DC DC-DC BUFF +5V Q306: 2SJ364 Q351: 2SC5195 FSET Q307: UN9214 HPF LPF BUFF Q824: 2SC5195 D806: MA2S077 D807: MA2S077 LO AMP TX/RX SW Q354: 2SC5195 Q353: 2SC5195 Q321: 2SC5195 Q322: 2SC5195 D321: MA2S077 D322: HVU350 TUNE DEV SW x2 BUFF Q823: 2SC5107 D804: MA2S077 D805: MA2S077 LO AMP TX/RX SW FI701: PBFC450R15DR Q304: 2SJ364 IC5: M623
SECTION 11 VOLTAGE DIAGRAM +3CPU D IC142 S-80928ALMP-DAR 4 3 5 2 6 1 C92 0.001 1 COM 2 NC 3 A 4 B KSD1 TXFL D58 MA6S121 2 S1007 3 S1008 5 S1011 6 S1012 D59 MA6S121 8 S1015 9 S1016 D54 MA2S111 0 S1019 KS1 AM AGC R+3 R+3 VIN VCC SPREMOTE IC202 M5222FP C214 2.2 R197 10 K R320 33 K C318 0.01 4 5 R203 68 C: 12.7 2 R210 12 K C209 0.001 Q202 XP1501 AB 1 R209 1K VCC C205 47 R211 10 K 3 1 C: 13.2 C208 0.001 R208 10K AFON R207 1M C162 0.001 C207 4.
R1 NTCCF20124AH 473KCT C737 0.01 SD NOISE TXC 2NDLO R2 100K 8 7 6 5 C907 0.001 R+3 R717 1K C708 0.1 R737 TBPS1R153K460H5Q C707 0.1 1 2 3 4 5 6 7 8 C735 0.1 R730 220 K OSCIN OSCOUT MIXOUT VCC IFIN DEC FILOUT FILIN 2 3 4 IC4 TC4W53FU THERMC C700 0.1 C906 0.001 2NDLO 2NDLO IFIN C712 33 P R727 22 K 3 38 GND DATA C713 0.001 40 39 THERM R732 4.7 K R731 180 K 1 GND 2 PSET PSET C733 0.001 C734 0.
SECTION 11 VOLTAGE DIAGRAM C361 0.047 KSD2 RXF1 4 S1010 7 S1014 5 S1011 8 S1015 6 S1012 9 S1016 D59 MA6S121 D54 MA2S111 *S1018 0 S1019 RXF2 TXInh50 D56 MA2S111 D57 MA2S111 C324 0.001 C317 0.047 R317 220 K J1 AXK6S40645P IOST R+3 SD NOISE +3C AGC R+3 VIN VCC SPREMOTE AM C201 0.047 R202 150 C77 0.001 R205 68 C202 3.3 R204 68 Q201 2SB1201 S C: 13.2 R203 68 4 5 C: 12.
11-2 RF UNIT 6MVCO3 +3 C822 0.01 +5V R815 3.3 K + C823 1.5 + C824 1.5 R819 10 K Q805 2SC4117 BL R876 2.7 K VLV GND ULV MOD SHIFT GND 12LV C864 0.22 SHIFTC C866 0.001 R877 47 K Q817 UN9211 C865 0.001 +3 + C844 0.22 R875 22 K MOD R862 6.8 K 7 6 5 4 3 2 1 SHIFT VT:3.3 VR:0 UT:3.3 UR:0 12T:3.3 12R:0 C305 2P L302 80 nH L301 0.82 µH VLV GND ULV MOD SHIFT GND 12LV C835 0.001 C836 0.001 12VCO3 IC802 TB31242FN C334 0.001 R301 270 K R871 15 K C858 0.
Q902 2SD2216 S C911 0.001 TXC Q901 UN9211 Q822 2SC5107 O 6M Q904 UN9211 00M VHF 9 D805 MA2S077 C890 5P Q908 UN9211 R900 4.7 K VT:4.1 VR:0 R909 4.7 K UHFTX Q911 2SA1588 GR D807 MA2S077 R+3 3 R133 L125 2.7 nH 22 R123 3.9 K 12T:0.7 12R:0 12TX 12T:4.1 12R:0 C899 0.001 R910 1K R914 10 K C72 0.001 C171 0.001 R916 1M C931 0.001 Q140 2SD2216 S C934 0.001 R128 4.7 K FI52 LFL30-13C1270B060 C60 0.001 C61 8P 5 IN 6 VCC 5 GND 4 OUT 10 C59 0.
R805 4.7 K R869 1K R804 4.7 K D321 MA2S077 C850 0.1 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 THERM GND IOST 37 AGC R+3 C702 0.1 PSET 38 R369 47 C372 0.001 L331 10 µH C369 7P CK 12C:2.8 L360 10 µH C363 0.01 R702 470 R701 100 K L701 1.8 µH C362 0.001 C364 12 P L330 22 nH D351 1SV270 Q350 2SC5006 C366 7P R360 10 K + R362 2.7 K C360 0.1 L332 15 nH R367 12 K R364 2.2 K C376 4P C378 1.5 P C380 3P Q353 2SC5195 C377 8P C379 24 P L334 6.8 nH Q351 2SC5195 L336 4.7 nH C816 0.
INTRODUCTION This service manual describes the latest service information for the IC-T81A/E at the time of publication. MODEL VERSION U.S.A. Australia S.E.Asia Europe U.K. Italy IC-T81A IC-T81E SYMBOL USA-1 AUS SEA EUR UK ITA To upgrade quality, all electrical or mechanical parts and internal circuits are subject to change without notice or obligation. DANGER NEVER connect the transceiver to an AC outlet or to a DC power supply that uses more than 16 V.
SERVICE MANUAL MULTIBAND FM TRANSCEIVER 1-1-32, Kamiminami, Hirano-ku, Osaka, 547-0003, Japan A-5566I-S-1 © 1999 Icom Inc.
