IC-T81_serv.pdf

《IC-T81_serv.pdf》由会员分享，可在线阅读，更多相关《IC-T81_serv.pdf（53页珍藏版）》请在收音机爱好者资料库上搜索。

1、SERVICE MANUAL MULTIBAND FM TRANSCEIVER INTRODUCTION DANGER ORDERING PARTS REPAIR NOTES This service manual describes the latest service information for the IC-T81A/E at the time of publication. NEVER connect the transceiver to an AC outlet or to a DC power supply that uses more than 16 V. Such a co

2、nnection could cause a fire hazard and/or electric. DO NOT expose the transceiver to rain, snow or any liquids. DO NOT reverse the polarities of the power supply when connecting the transceiver. DO NOT apply an RF signal of more than 20 dBm (100mW) to the antenna connector. This could damage the tra

3、ns- ceivers front end. 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 1130009370 S.ICTB31242FNIC-T81A/E RF UNIT1 pieces 8810008990 ScrewPH BT M2x10 ZK

4、 IC-T81A/E Chassis10 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 until the transceiver is disconnected from its power source. 3. DO NOT force any of the variable c

5、omponents. Turn them slowly and smoothly. 4. DO NOT short any circuits or electronic parts. An insulated turning tool MUST be used for all adjustments. 5. DO NOT keep power ON for a long time when the transceiver is defective. 6. DO NOT transmit power into a signal generator or a sweep generator. 7.

6、 ALWAYS connect a 40 dB to 50 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. To upgrade quality, all electrical or mechanical parts

7、and internal circuits are subject to change without notice or obligation. MODEL IC-T81A IC-T81E VERSION U.S.A. Australia S.E.Asia Europe U.K. Italy SYMBOL USA-1 AUS SEA EUR UK ITA TABLE OF CONTENTS SECTION1SPECIFICATIONS SECTION2INSIDE VIEWS SECTION3DISASSEMBLY INSTRUCTIONS SECTION4CIRCUIT DESCRIPTI

8、ON 4-1RECEIVER CIRCUITS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-1 4-2TRANSMITTER CIRCUITS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-3 4-3PLL CIRCUITS . . . . . . . . . . . . .

9、. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-5 4-4POWER SUPPLY CIRCUITS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-5 4-5 PORT ALLOCATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

10、. . . . . . . . . . . . . . . . . . . . . . .4-6 SECTION5ADJUSTMENT PROCEDURES 5-1PREPARATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-1 5-2PLL ADJUSTMENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

11、 . . . . . . . . . . . . . . . . . . . .5-2 5-3RECEIVER ADJUSTMENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-4 5-4TRANSMITTER ADJUSTMENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-8 SECTION6P

12、ARTS LIST SECTION7MECHANICAL PARTS AND DISASSEMBLY SECTION8SEMI-CONDUCTOR INFORMATION SECTION9BOARD LAYOUTS 9-1LOGIC UNIT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9-1 9-2RF UNIT . . . . . . . . . . . . . . . . . . . . . .

13、. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9-3 9-3VCO BOARD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9-5 SECTION10BLOCK DIAGRAM SECTION11VOLTAGE DIAGRAM 11-1LOGIC UNIT . . . . . . . .

14、. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11-1 11-2RF UNIT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11-2 MGENERAL Frequency range: * 1 Specifications guara

15、nteed 144 148 MHz, * 2 Specifications guaranteed 430 440 MHz * 3 Specifications guaranteed 440 450 MHz, * 4 Not guaranteed Mode: FM and AM (RX only), WFM (Rx only) No. of memory channels: 124 (incl. 10 pairs of scan edges and 4 call channels) Frequency stability: 3 ppm max. (10C to +60C; 14F to 140F

16、) Tuning steps: 5*, 10, 12.5, 15*, 20, 25, 30, 50 and 100 kHz *Not available for 1200 MHz band Usable tempareture range: 10C to +60C; 14F to 140F Usable battery pack/case: BP-198, BP-199, BP-200 and BP-197 Power supply requirement: 4.5 16 V DC or specified battery pack Polarity: Negative ground Freq

17、uency resplution: 5 kHz and 12.5 kHz (10 kHz and 12.5 kHz for 1200 MHz band) Current drain (at 13.5 V DC) : (typical value) Anntena connector: SMA (50 ) Dimensions (projections not included): 58(W) 106(H) 28.5(D) mm;2516(W) 4316(H) 118(D) in Weight (with BP-197/Ant.): 290 g; 10.2 oz MTRANSMITTER Out

18、put power (at 13.5 V DC): High5.0 W typical (1.0 W at 1200 MHz band) Low1.0 W typical (0.1 W at 1200 MHz band) Modulation system:Variable reactance modulation Max. freq. deviation: 5 kHz Spurious Emissions: Less than 60 dB (50 MHz, 144 MHz and 440 MHz) Less than 40 dB (other) Less than 50 dB (Europe

19、 version at 1200 MHz) External MIC connector: 3-conductor 2.5(d) mm (18”); 2 k SECTION 1SPECIFICATIONS 1 - 1 Version U.S.A. Australia S.E.Asia Europe, U.K. Italy 50 MHz 50 53.995 50 53.995 50 53.995 50 52 50 52 145 MHz TX: 144 148 RX: 118 173.995* 1 144 148 TX: 136 173.995* 1 RX: 118 173.995* 1 144

20、146 TX: 136 173.995* 1 RX: 118 173.995* 1 440 MHz TX: 430 450* 3 RX: 400 469.995* 3 430 440 400 469.995*2 430 440 400 469.995*2 1200 MHz 1240 1300 1240 1300 1240 1300 1240 1300 1240 1300 91.5 MHz (RX only) 76 107.995*4 88 107.995* 4 76 107.995*4 88 107.995* 4 88 107.995*4 TX RX High power Low power

21、Rated output Standby Power saved 50/144 MHz 1.4 A 0.6 A 440 MHz 1.3 A 0.5 A 1200 MHz 0.8 A 0.4 A 220 mA 80 mA (at 9.6 V) 40 mA (at 9.6 V) 1 - 2 MRECEIVER Receiver system: Double-conversion superheterodyne Intermediate frequency: 1st69.45 MHz (13.35 MHz: WFM) 2nd 450 kHz Sensitivity*: (except spuriou

22、s points; typical values) * FM and WFM are measured at 12 dB SINAD, AM is measured at 10 dB S/N. Squelch sensitivity: 50, 144, 440 MHzLess than 0.18 V (Threshold) 1200 MHzLess than 0.25 V (Threshold) AM (50 MHz only)Less than 0.56 V (Threshold) WFMLess than 5.6 V (Threshold) Selectivity (except WFM)

23、: More than 15 kHz/6 dB Less than 30 kHz/60 dB Spurious and image rejection ratio : 50, 144 MHzMore than 60 dB 440 MHzMore than 50 dB 1200 MHzMore than 38 dB (except half IF, 2nd image, 50 MHz band IF and WFM) Audio output power: 250 mW typical at 10 % distortion with an 8 load All stated specificat

24、ions are subject to change without notice or obligation. Band 50 MHz 144 MHz 440 MHz 1200 MHz 91.5 MHz FM 0.18 V 0.18 V 0.18 V 0.25 V AM 0.56 V WFM 2.0 V 2 - 2 SECTION 2INSIDE VIEWS LOGIC UNIT RF UNIT IF IC (IC701: TA31136FN) Crystal filter (X1: CR-639 5.039MH) AF power amplifier (IC201: TA7368F) AF

25、 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: XP6401) PLL IC (IC801: PD3140G) Drive amplifier (Q921: MRF9745) Power amplifier (Q922: 2SK3075) TOP

26、 VIEWBOTTOM VIEW APC control circuit 3 - 1 SECTION 3DISASSEMBLY INSTRUCTIONS A B Chassis panel C E E D Sealing rubber J1 LOGIC unit D Chassis panel F F LOGIC unit F Shield plate REMOVING THE CHASSIS PANEL 1 Remove 1 knob A, and unscrew 1 nut B. 2 Unscrew 2 screws C. 3 Remove the chassis panel in the

27、 direction of the arrow. REMOVING THE 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 of the arrow. REMOVING THE RF UNIT 1 Unsolder 1 point, G,

28、 to separate ANT plug. 2 Unscrew 8 screws, H, to separate the RF unit. 3 Remove the RF unit in the direction of the thick arrow. REMOVING THE SHIELD PLATE 1 Unsolder 10 points, F, to separate the shield plate and LOGIC unit. H H G ANT plug RF unit 4 - 1 SECTION 4CIRCUIT DESCRIPTION 4-1 RECEIVER CIRC

29、UITS 4-1-1 DUPLEXER CIRCUIT (RF UNIT) The transceiver has a duplexer (low-pass and high-pass fil- ters) on the frist stage from the antenna connector to sepa- rate the signals into below UHF and SHF signals. The high- pass filter (L51L55, C41C46 and C48C50) is for SHF (1200 MHz) signal and the low-p

30、ass filter (C9, C10, C12C14 and L7L9) is for below UHF (50 MHz, 144 MHz, 440 MHz and WFM) signals. The filtered SHF signal is applied to the low-pass fileter (C51C54, L56 and L57). The RF signals below UHF pass through the duplexer circuit and are separated into VHF (50 MHz, 144 MHz and WFM band) an

31、d UHF (440 MHz band) signals. The high-pass fil- ter (C4C8, L5, L6) is for UHF (440 MHz band) signal and the low-pass filter (C15C20, L10L12) is for VHF (50 MHz, 144 MHz and WFM band) signals. The VHF signals are applied to the another duplexer circuit for separation into 50 MHz and above WFM band s

32、ignals. The high-pass filter (C21C24, C84 and L13L15) is for 144 MHz and WFM band signals and the low-pass filter (C27C33 and L16L18) is for 50 MHz band signal. The separated signals are applied to each RF circuits. 4-1-2 ANTENNA SWITCHING CIRCUITS (RF UNIT) The antenna switching circuit functions a

33、s a low-pass filter while receiving. However, its impeadance becomes very high while transmitting by applying a current to D101 and D102 (50 MHz), D302 and D303 (144MHz and WFM), D402 and D403 (440 MHz), D51 and D52 (1200 MHz). Thus, transmit signals are blocked from entering the receiv- er circuits

34、. The antenna switching circuit employs a 1/4 type diode switching system. The passed signals are then applied to each RF amplifier circuit. 4-1-3 50 MHz BAND RF CIRCUIT (RF UNIT) The RF circuit amplifies signals within the range of frequen- cy coverage and filters out-of-band signals. The signals f

35、rom the antenna switching circuit (D101 and D102) are amplified at the RF amplifier (Q101). The ampli- fied signals pass through the tunable bandpass filter (L108L110, C115, C117, C120, D106, D107) to suppress out-of-band signals, and are then applied to the 1st mixer circuit (IC601, pin 1). 4-1-4 1

36、44 MHz AND WFM BANDS RF CIRCUITS (RF UNIT) The signal from the antenna switching circuit (D302, D303) are applied to the each band-pass fileters and RF amplifier. RF signals 144 MHz band The 144 MHz band signals are applied to the RF amplifier (Q301) via the tunable bandpass filter (L303, L304, C306

37、, D306). The amplified signals pass through the tunable band- pass filter (C318C321, D309, D310, L305, L306), and are then applied to the 1st mixer circuit (IC601, pin 1). RF CIRCUIT 1st mixer HPFLPF ANT SW RF BPF RF BPF ANT SHF band (1200 MHz) LPF ANT SW RF BPF RF UHF band (440 MHz) HPF HPF ANT SW

38、BPF RF BPF VHF band (144 MHz) LPF BPF RF BPF WFM band (RX only) ANT SW RF BPF VHF band (50 MHz) LPF IC601 1st LO BPF XTAL BPF CERAMIC D601 Mode SW D602 Mode SW FM mode FI601 69.45 NHz WFM mode FI602 13.35 NHz LEVEL CONV. D51, D52Q51FI51IC51FI52 D402, D403Q401FI401IC501 D302, D303D306Q301D309, D310 D

39、202Q201 D203 Q101 D106, D107 D101, D102 to IF amp. (Q701) Q9 TUNE signal from IC5, pin 11 (LOGIC unit) 4 - 2 RF signals WFM band The WFM band signals are applied to the RF amplifier (Q201) via the tunable band-pass filter (D202). The ampli- fied signals pass through the tunable bandpass filter (D203

40、), and are then applied to the 1st mixer circuit (IC601, pin 1). Varactor diodes (D106, D107, D202, D203, D306, D309, D310) are employed by the tunable bandpass filter to tune the center frequency of the bandpass filter. These diodes are controlled by the PLL lock voltage and obtain good image respo

41、nse rejection. 4-1-5 440 MHz BAND RF CIRCUIT (RF UNIT) The signals from the antenna switching circuit (D402 and D403) are amplified at the RF amplifier (Q401). The ampli- fied signals pass through the bandpass filter (FI401), and are then applied to the 1st mixer circuit (IC601, pin 1) after being a

42、mplified at another RF amplifier (IC501). 4-1-6 1200 MHz BAND RF CIRCUIT (RF UNIT) The signals from the antenna switching circuit (D51 and D52) are amplified at the RF amplifier (Q51). The amplified signals pass through the bandpass filter (FI51), and are then applied to the RF amplifier (IC51). The

43、 amplified signal is applied to the 1st mixer circuit (IC601, pin 1) via the band- pass filter (FI52). 4-1-7 1ST MIXER CIRCUIT (RF UNIT) The 1st mixer circuit converts the received RF signals into a fixed frequency of the 1st IF signal with a 1st LO output fre- quency. By changing the PLL frequency,

44、 only the desired frequency will pass through at the next stage of the 1st mixer. 1st mixer circuit produces the different 1st IF signal for WFM and other band 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

45、 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 cir

46、cuit (LOGIC unit; IC701, pin 16). WFM band The RF signals are mixed with 1st LO signals at the 1st mixer (IC601) to produce a 13.35 MHz 1st IF signal. The 1st IF signal is output from the 1st mixer (IC601, pin 6), and then passed through the 1st IF filter (FI602) to suppress unwant- ed harmonic comp

47、onents. The filtered signal is applied to the 2nd mixer circuit (LOGIC unit; IC701, pin 16). The 1st LO signals are gererated at the VCO circuit which consists of Q301, Q302, D301, Q311, Q312, D302, D311 for 50 MHz, 144 MHz and WFM, Q321, Q322, D321, D322 for 440 MHz, Q350, D351, D352 for 1200 MHz o

48、n the VCO unit. The 1st LO signal for 50, 144, 440, WFM band The 1st LO signals which are generated on the VCO unit are applied to the buffer-amplifier (Q313 and D312 for 50 MHz, 144 MHz and WFM, Q323 for 440 MHz). The buffer-ampli- fied signals are applied to the LO-amplifier (Q822 for 50 MHz, 144

49、MHz and WFM, Q823 for 440 MHz), and are then applied to the 1st mixer circuit via the TX/RX switch (D802 and D803 for 50 MHz, 144 MHz and WFM, D804 and D805 for 440 MHz) on the RF unit. The 1st LO signal for 1200 MHz band The 1st LO signals which are generated on the VCO unit are applied to the buffer-amplifier (Q351). The buffer-amplified signals are applied to the doubler circuit (Q353), and pass- es through the high-pass and low-pass filter. The filtered sig- nals are applied to the 1st m