IC2720H_serv.pdf

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1、DUAL BAND FM TRANSCEIVER i2720H SERVICE MANUAL INTRODUCTION This service manual describes the latest service information for the IC-2720H DUAL BAND FM TRANSCEIVER at the time of publication DANGER NEVER connect the transceiver to an AC outlet or to a DC power supply that uses more than 16 V. This wi

2、ll ruin the transceiver. 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 (100 mW) to the antenna connector. This could damage the transceiv- ers front end. ORD

3、ERING 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 1110004310S.ICM62352GPIC-2720H MAIN UNIT5 pieces 8810009610 Screw FH M2.66 ZK IC-2720H bott

4、om 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 variab

5、le components. Turn them slowly and smoothly. 4. DO NOT short any circuits or electronic parts. 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 genera

6、tor. 7. ALWAYS connect a 50 dB to 60 dB attenuator between the transceiver and a deviation meter or spectrum ana- lyzer when using such test equipment. 8. READ the instructions of test equipment thoroughly before connecting equipment to the transceiver. To upgrade quality, any electrical or mechanic

7、al parts and internal circuits are subject to change without notice or obligation. MODEL IC-2720H VERSION U.S.A. Korea S.E.Asia Export SYMBOL USA KOR SEA EXP TABLE OF CONTENTS SECTION 1SPECIFICATIONS SECTION 2INSIDE VIEWS SECTION 3DISASSEMBLY INSTRUCTIONS SECTION 4CIRCUIT DESCRIPTION 4 - 1RECEIVER C

8、IRCUITS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4 - 1 4 - 2TRANSMITTER CIRCUITS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4 - 5 4 - 3PLL CIRCUITS . .

9、. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4 - 6 4 - 4POWER SUPPLY CIRCUITS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4 - 8 4 - 5CPU PORT ALLOCATIONS

10、 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4 - 10 SECTION 5PARTS LIST SECTION 6MECHANICAL PARTS AND DISASSEMBLY SECTION 7SEMI-CONDUCTOR INFORMATION SECTION 8BOARD LAYOUTS 8 - 1CONTROL UNIT . . . . . . . . . . . . . . . . . . . . . .

11、. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 - 1 8 - 2MAIN UNIT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8 - 3 8 - 3VCO UNIT . . . . . . . . . . . . . . . . . . .

12、. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8 - 5 SECTION 9BLOCK DIAGRAM SECTION 10VOLTAGE DIAGRAMS 10 - 1 CONTROL UNIT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

13、 10 - 1 10 - 2 MAIN AND VCO UNITS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10 - 2 1 - 1 SECTION 1SPECIFICATIONS All stated specifications are subject to change without notice or obligation. MGENERAL Frequency range: LEFT SIDE

14、RIGHT SIDE *1Guaranteed 144.000 146.000 MHz only, *2Guaranteed 144.000 148.000 MHz only, *3Guaranteed 430.000 440.000 MHz only; *4Guaranteed 440.000 450.000 MHz only *5Not guaranteed range Mode: FM, AM (AM range is 118.0 135.995 MHz and Rx only for USA and EXP.) Nomber of memory channel: 212 (includ

15、ing 2 call channels and 10 scan edges) Usable temperature range: 10C to +60C; +14F to +140F Frequency resolution: 5, 10, 12.5, 15, 20, 25, 30 and 50 kHz Frequency stability: 10 ppm (10C to +60C; +14F to +140F) Power supply requirement: 13.8 V DC 15 % (negative ground) Current drain (at 13.8 V DC): R

16、eceiveStandby (squelched)1.2 A Max. audio output1.8 A Transmit at VHF 50 W/UHF 35 W12.0 A/11.0 A Antenna connector: SO-239 (50 ) DATA connector: Mini DIN 6 pin Dimensions : Controller140(W)50(H)27(D) mm; 512(W)13132(H)1116(D) inch (projections not included)Main unit140(W)40(H)187(D) mm; 512(W)1916(H

17、)738(D) inch Weight: Controller150 g; 5.29 oz Main unit1.4 kg; 3.0 lb MTRANSMITTER Output power: VHF50 W/25 W/5 W (selectable) UHF35 W/25 W/5 W (selectable) Modulation system: Variable reactance frequency Maximum frequency deviation: 5.0 kHz Spurious emissions: Less than 60 dB Microphone connector:

18、8-pin modular jack (600 ) MRECEIVER Receive system: Double-conversion superheterodyne Intermediate frequency: 1st IF38.85 MHz/46.05 MHz (Left/right side band)2nd IF450 kHz/455 kHz Sensitivity: Less than 0.18 V (at 12 dB SINAD) Squelch sensitivity: Less than 0.13 V (at threshold) Selectivity: More th

19、an 12 kHz/6 dB (Wide);More than 6 kHz/6 dB (Narrow) Less than 30 kHz/60 dB (Wide);Less than 20 kHz/60 dB (Narrow) Spurious and image rejection : More than 60 dB Audio output power (at 13.8 V): More than 2.4 W at 10% distortion with an 8 load External speaker connector: 2-conductor 3.5(d) mm (18)/8 V

20、ERSION KOR SEA EXP USA RX (MHz) 144.000146.000, 430.000440.000 136.000179.995* 2, 430.000440.000 118.000549.995* 2 118.000549.995* 2, *4 TX (MHz) 144.000146.000, 430.000440.000 140.000150.000* 2, 430.000440.000 136.000174.000* 2, 400.000479.000*3 144.000148.000, 430.000450.000* 4 VERSION KOR SEA EXP

21、 USA RX (MHz) 144.000146.000, 430.000440.000 136.000173.995* 2, 430.000440.000 118.000179.995* 2, 375.000549.995*3 810.000999.990* 5 118.000174.000* 2, 375.000549.995*4, 810.000824.000* 5, 849.000869.000*5, 894.000999.990* 5 TX (MHz) 144.000146.000, 430.000440.000 140.000150.000* 2, 430.000440.000 1

22、36.000174.000* 2, 400.000479.000*3 144.000148.000, 430.000450.000* 4 SECTION 2INSIDE VIEWS 2 - 1 CONTROL UNIT (TOP VIEW) Key back lightKey back light (DS14, DS15: LN1371G) LCD back light (DS14, DS15: LN1371G) LCD back light DS1-3, DS7-9: SML-010MT DS1-3, DS7-9: SML-010MT DS4-6, DS10-12: SML-020MLT K

23、ey back light DS4-6, DS10-12: SML-020MLT Key back light (DS16, DS17: LN1371G) Key back light (DS16, DS17: LN1371G) Key back light (DS15, DS18: LN1371G)(DS15, DS18: LN1371G) Key back light (DS14, DS15: LN1371G) LCD back light DS1-3, DS7-9: SML-010MT DS4-6, DS10-12: SML-020MLT Key back light (DS16, DS

24、17: LN1371G) Key back light (DS15, DS18: LN1371G) MAIN UNIT (TOP VIEW) VHF low-pass filter Power amplifier VHF low-pass filter Power amplifier (Q27: RD70HVF1) Drive amplifier (Q27: RD70HVF1) Drive amplifier (Q25: 2SK3075) Main CPU (Q25: 2SK3075) Main CPU (IC2013: HD64F2144AFA20) VCO unit AF amplifie

25、r (IC2013: HD64F2144AFA20) VCO unit AF amplifier (IC2012: LA4445)(IC2012: LA4445) VHF low-pass filter Power amplifier (Q27: RD70HVF1) Drive amplifier (Q25: 2SK3075) Main CPU (IC2013: HD64F2144AFA20) VCO unit AF amplifier (IC2012: LA4445) VHF RX Pre amplifier (Q33: 3SK272) UHF RX Pre amplifier (Q24:

26、3SK274) Drive amplifierDrive amplifier (Q25: 2SK3075)(Q25: 2SK3075) TX pre-amplifier (Q16: 2SK2854) CONTROL UNIT (BOTTOM VIEW) Dimmer +8V regurator Dimmer +8V regurator (Q1: 2SC4116) +5V regurator (Q1: 2SC4116) +5V regurator (IC3: TA78L05F) Sub CPU (IC3: TA78L05F) Sub CPU (IC4: HD6473847RH) Reset IC

27、 (IC4: HD6473847RH) Reset IC (IC2: S-80945CLMC) Data comparator (IC2: S-80945CLMC) Data comparator (IC1: TA75S01F)(IC1: TA75S01F) Mic amplifierMic amplifier IC5: TA75S558F IC5: TA75S558F Q15: 2SC4116 Q15: 2SC4116 Dimmer circuit (Q6-Q13: 2SC4116) +8V regurator Q1: 2SC4116 Q3: 2SA1586 D1: MA8091 +5V r

28、egurator (IC3: TA78L05F) Control unit CPU (IC4: HD6473847RH) Reset IC (IC2: S-80945CLMC) Data comparator (IC1: TA75S01F, D2: MA8047) Mic amplifier IC5: TA75S558F Q15: 2SC4116 MAIN UNIT (BOTTOM VIEW) D/A converterD/A converter (IC1: M62352GP) +8V regurator (IC1: M62352GP) +8V regurator (IC2003: TA780

29、8F) Mic amplifier (IC2003: TA7808F) Mic amplifier (IC2014: TA75S558F)(IC2014: TA75S558F) Analog switchAnalog switch IC2007: BU4066BCFV IC2007: BU4066BCFV IC2010: BU4066BCFV IC2010: BU4066BCFV D/A converter (IC1: M62352GP) UHF low-pass filter circuit Ceramic bandpass filters FI1000: CFWM450E FI1001:

30、CFWS450HT FI1002: CFWM455E APC amplifier (IC2: TA75S01F) PLL circuit +5V regurator (IC2002: TA7805F) +8V regurator (IC2003: TA7808F) Mic amplifier (IC2014: TA75S558F) Analog switch IC2007: BU4066BCFV IC2008: BU4066BCFV IC2010: BU4066BCFV FM IF IC IC1001: TA31136FN IC1004: TA31136FN 2 - 2 SECTION 3DI

31、SASSEMBLY INSTRUCTIONS Removing the MAIN unit Unscrew 8 screws A, and remove the cover. Disconnect two cables B from J1 and J2007. Remove the clip c. A A B C J2007 J1 G F G F H E MAIN UNIT J I Unsolder 3 points E. Unscrew 4 screws F. Unsolder 4 points G, and remove the cover H. Unscrew 2 screws I. U

32、nscrew 12 screws J, and remove MAIN unit. 3 - 1 Removing the CONTROL unit Remove 6 knobs A. A A Unscrew 4 screws B, and remove the cover. Remove the plate C, and remove CONTROL unit. B C CONTROL UNIT 3 - 2 4 - 1 SECTION 4CIRCUIT DESCRIPTION 4-1 RECEIVER CIRCUITS 4-1-1 TRIPLEXER AND RX BAND SWITCHING

33、 CIRCUITS (MAIN UNIT) The transceiver has a triplexer (low-pass and high-pass fil- ters) on the first stage from the antenna connector to sepa- rate the signals into VHF and UHF signals. The RF signals from the antenna connector are applied to the tripler or RX band swtich circuits. RF SIGNALS V-V (

34、118 MHz180 MHz), U-V (136 MHz174 MHz) The V-V and U-V RF signals from the antenna connector pass through the low-pass filter (L76, L77, L80, C205, C209, C242, C243, C264), and then applied to the TX/RX switching circuit (D42, D46, D52, D67, D2049). The filtered signals are amplified at the pre-ampli

35、fier (Q33), and are applied to the left side or right side displayed RX circuits. RF SIGNALS U-U, V-U2 (375 MHz550 MHz) The U-U and V-U2 RF signals from the antenna connector pass through the high-pass filter (L78, L81, C206, C210, C213, C265), and then applied to the TX/RX switching circuit (D55, D

36、64, D65, D2050) via the SWR detector (D50, D58). The filtered signals are amplified at the pre-amplifier (Q24), and are applied to the left side or right side displayed RX cir- cuits. RF SIGNALS U-U3 (810 MHz1000 MHz) The U-U3 RF signals from the antenna connector pass through the two low-pass filte

37、rs (L76, L77, L80, C205, C209, C242, C243, C264, L87, L88, C266C268), and are then applied to the RX band swtiching circuit (D2061). The filtered signals are amplified at the RF amplifier (Q18), and are applied to the right side displayed RX circuits. RF SIGNALS V220 (174 MHz260 MHz), V-U1 (225 MHz3

38、75 MHz) The V220 and V-U1 RF signals from the antenna connector are applied to the RX band swtiching circuit (Q34, D66, RL1), and are applied to the left side displayed RX circuit. 4-1-2 RF CIRCUIT FOR LEFT SIDE DISPLAY (MAIN UNIT) RF SIGNALS V-V (118 MHz180 MHz) The amplified signals are applied to

39、 the RF amplifier (Q29) after being passed through the attenuator (D59) and band- pass filter (D47, D53). The signals are applied to the RX band switching circuit (D28) via the another bandpass filter (D32, D39) to supress the unwanted signals. RF SIGNALS V220 (174 MHz260 MHz) The signals are applie

40、d to the RF amplifier (Q31) after being passed through the RX band switching circuit (D62) and bandpass filter (D51). The amplified signals are applied to the RX band switching circuit (D28) via the another bandpass filter (D34) to supress the unwanted signals and attenuator (R195R197). RF SIGNALS V

41、-U1 (225 MHz375 MHz) The signals are applied to the RF amplifier (Q32) after being passed through the RX band switching circuit (D63) and bandpass filter (D49). The amplified signals are applied to the RX band switching circuit (D31) via the attenuator (R198R200) and another bandpass filter (D35) to

42、 supress the unwanted signals. RF SIGNALS V-U2 (375 MHz550 MHz) The amplified signals are applied to the RF amplifier (Q20) after being passed through the attenuator (D25) and band- pass filter (D23, D73). The signals are applied to the RX band switching circuit (D9) via the another bandpass filter

43、(D13, D17) to supress the unwanted signals. BPFBPF ANTENNA 1st mixer (IC1005) 1st LO to 2nd mixer circuit ATT RX SW RFPRE BPFBPFATT RX SW RFPRE BPFBPFATT RX SW RX SW RX SW RF BPFBPFATT RX SW RX SW RF D59Q29 V-V (118 MHz174 MHz) V220 (174 MHz260 MHz) V-U1 (225 MHz375 MHz) V-U2 (375 MHz550 MHz) D28D32

44、, D39D47, D53 D62Q31D30D34D51 D63Q32D31D35D49 Q33 Q34, D66, RL1 D25Q20D9D13, D17D23, D73Q24 RF CIRCUIT FOR LEFT SIDE DISPLAY 4 - 2 The signals from the RX band swtiching circuits are then applied to the left side displayed 1st mixer circuit (IC1005, pin 6). 4-1-3 1ST MIXER AND 1ST IF CIRCUIT FOR LEF

45、T SIDE DISPLAY (MAIN UNIT) The 1st mixer circuit converts the received RF signals to a fixed frequency of the 1st IF signal with a PLL output fre- quency. By changing the PLL frequency, only the desired fre- quency will pass through the bandpass filter at the next stage of 1st mixer circuit. The RF

46、signals are mixed with 1st LO signals at the 1st mixer (IC1005) to produce a 38.85 MHz 1st IF signal. The 1st IF signal is output from pin 1, and passed through the crystal bandpass filter (FI1003) to suppress unwanted harmonic components. The filtered signal is amplified at the IF amplifi- er (Q104

47、0) after being passed through the limiter circuit (D1021). The amplified signal is applied to the 2nd mixer cir- cuit (IC1001). 4-1-4 2ND IF AND DEMODULATOR CIRCUITS FOR LEFT SIDE DISPLAY (MAIN UNIT) The 2nd mixer circuit converts the 1st IF signal to a 2nd IF signal. A double conversion superhetero

48、dyne system (which converts receive signal twice) improves the image rejection ratio and obtains stable receiver gain. The FM IC IC (IC1001) contains the 2nd mixer, limiter and noise amplifiers, quadrature detector, S-meter detector, active filter circuits, etc. A 2nd LO signal (38.4 MHz) is pro- du

49、ced at the PLL circuit by dividing its reference frequency. The 38.85 MHz 1st IF signal from the IF amplifier (Q1040) is applied to the 2nd mixer section of the FM IF IC (IC1001, pin 16), and is mixed with the 2nd LO signal (38.4 MHz) to be converted to a 450 kHz 2nd IF signal. The 2nd IF signal is applied to the each demodulator circuits by AM or FM mode. FM MODE The 2nd IF signal is output from the FM IF IC (IC1001, pin 3) and passes through the ceramic bandpass filter (FI1001). The filtered signal is fed back to the IC,