IC-2800H_serv.pdf

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1、A-5570MI-S 1999 by Icom Inc.6-9-16, Kamihigashi, Hirano-ku, Osaka 547-0002, Japan Count on us! DUAL BAND FM TRANSCEIVER iC-2800h iC-2800h Downloaded by? ? Amateur Radio Directory INTRODUCTION This service manual describes the latest service information for the IC-2800H FM TRANSCEIVER at the time of

2、publication. To upgrade quality, all electrical or mechanical parts and inter- nal 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. Such a connection could cause a fire hazard and/or el

3、ectric shock. DO NOT expose the transceiver to rain, snow or any liq- uids. 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 transceivers front end. ORDERING PARTS

4、 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 1110002750 S.ICTA75S01FIC-2800H MAIN UNIT 1 piece 8810008450 Screw M4 8 ZKIC-2800H CHASSIS6 pieces Add

5、resses 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 variable components. Turn th

6、em 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 transceiver is defective. 6. DO NOT transmit power into a signal generator or a sweep generator. 7. ALWAYS connect a

7、 50 dB or 60 dB attenuator between the transceiver and a deviation meter or spectrum analyser when using such test equipment. 8. READ the instructions of test equipment thoroughly before connecting equipment to the transceiver. MODEL VERSION SYMBOL Europe Italy U.S.A. S. E. Asia IC-2800H USA SEA EUR

8、 ITA CSAC. S. America 6-9-16, Kamihigashi, Hirano-ku, Osaka 547-0002, Japan Phone : 06 6793 5302 Fax: 06 6793 0013 Communication Equipment Himmelgeister Str. 100, D-40225 Dsseldorf, Germany Phone: 0211 346047Fax : 0211 333639 URL: Unit 9, Sea St., Herne Bay, Kent, CT6 8LD, U.K. Phone: 01227 741741 F

9、ax : 01227 741742 URL: http:/www.icomuk.co.uk Zac de la Plaine, Rue Brindejonc des Moulinais BP 5804, 31505 Toulouse Cedex, France Phone: 561 36 03 03Fax : 561 36 03 00 URL: http:/www.icom- 2380 116th Avenue N.E., Bellevue, WA 98004, U.S.A. Phone: (425) 454-8155Fax : (425) 454-1509 URL: Phone: (425)

10、 454-7619 A.C.N. 006 092 575 290-294 Albert Street, Brunswick, Victoria, 3056, Australia Phone: 03 9387 0666Fax : 03 9387 0022 URL: .au 6F No. 68, Sec. 1 Cheng-Teh Road, Taipei, Taiwan R.O.C. Phone: (02) 2559 1899Fax : (02) 2559 1874 A Division of Icom America Inc. 3071 #5 Road, Unit 9, Richmond, B.

11、C., V6X 2T4, Canada Phone: (604) 273-7400Fax : (604) 273-1900 Crta. de Gracia a Manresa Km. 14,750 08190 Sant Cugat del Valles Barcelona, SPAIN Phone: (93) 590 26 70 Fax : (93) 589 04 46 URL: TABLE OF CONTENTS SECTION 1 SPECIFICATIONS SECTION 2INSIDE VIEWS SECTION3 DISASSEMBLY INSTRUCTIONS SECTION 4

12、CIRCUIT DESCRIPTION 4 - 1 RECEIVER CIRCUITS . 4 1 4 - 2 TRANSMITTER CIRCUITS . 4 3 4 - 3 PLL CIRCUIT. 4 4 4 - 4 POWER SUPPLY CIRCUITS . 4 5 4 - 5 CPU PORT ALLOCATIONS . 4 5 SECTION 5ADJUSTMENT PROCEDURES 5 - 1 PREPARATION. 5 1 5 - 2 PLL AND TRANSMITTER ADJUSTMENTS. 5 2 5 - 3 RECEIVER ADJUSTMENT . 5

13、4 SECTION 6PARTS LIST SECTION 7 MECHANICAL PARTS AND DISASSEMBLY SECTION 8SEMI-CONDUCTOR INFORMATION SECTION 9 BOARD LAYOUTS 9 - 1 CONTROL UNIT. 9 1 9 - 2 MAIN UNIT. 9 3 SECTION 10 BLOCK DIAGRAM SECTION 11 VOLTAGE DIAGRAM 11 - 1 CONTROL UNIT.11 1 11 - 2 MAIN UNIT.11 2 MGENERAL Frequency range: *1Gua

14、ranteed 144.000 148.000 MHz only *2Guaranteed 430.000 440.000 MHz only; *3Guaranteed 440.000 450.000 MHz only Mode: FM, AM (118.0 135.995; Rx only) Nomber of memory channel: 232 (incl. 6 pairs of scan edges, 10 log, 10 repeater and 2 call channels) Usable temperature range: 10C to +60C; +14F to +140

15、F 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): ReceiveStandby (squelched)1.2 A Max. audio1.5 A Transmit at VHF 50 W/UHF 35 W12.0 A/11.0 A

16、at 25 W/25 W (TPE version)8.0 A Antenna connector: SO-239 (50 ) DATA connector: Mini DIN 6 pin External VIDEO input: PHONO RCA (75 ) Dimensions : Controller140(W)70(H)34(D) mm; 512(W)234(H)11132(D) inch (projections not included)Main unit140(W)40(H)165.8(D) mm; 512(W)1916(H)61732(D) inch Weight: Con

17、troller290 g; 10.2 oz Main unit1.15 kg; 2 lb 9 oz MTRANSMITTER Output power: HighVHF 50 W/UHF 35 W Mid-Happrox. 20 W Mid-Lapprox. 10 W Lowapprox. 5 W Modulation system: Variable reactance frequency Maximum frequency deviation: 5.0/2.5* kHz*EUR and ITA versions only Spurious emissions: Less than 60 d

18、B Microphone connector: 8-pin modular (600 ) MRECEIVER Receive system: Double-conversion superheterodyne Intermediate frequency: VHF1st IF 15.65 MHz2nd IF 450 kHz UHF1st IF 46.05 MHz2nd IF 450 kHz Sensitivity (at 12 dB SINAD): Less than 0.18 V Squelch sensitivity (threshold): Less than 0.13 V Select

19、ivity (wide/narrow): More than 12/6* kHz at 6 dB Less than 28/18* kHz at 60 dB *EUR and ITA versions only Spurious and image rejection : More than 60 dB Intermodulation rejection ratio : More than 60 dB Audio output power (at 13.8 V): More than 2.4 W at 10% distortion with an 8 load External SP1 con

20、nector: 2-conductor 3.5(d) mm (18)/8 External SP2 connector: 3-conductor 3.5(d) mm (18)/8 1 - 1 SECTION 1SPECIFICATIONS 144 MHz band440 MHz band 144.000 146.000430.000 440.000 Rx: 136.000 174.000*1Rx: 400.000 530.000*2 Tx: 144.000 148.000*1Tx: 430.000 440.000*2 Rx: 118.000 174.000*1 430.000 450.000*

21、3 Tx: 144.000 148.000*1 Rx: 136.000 174.000*1 430.000 440.000 Tx: 144.000 148.000*1 Rx: 118.000 174.000*1Rx: 400.000 530.000*2 Tx: 144.000 148.000*1Tx: 430.000 440.000*2 All stated specifications are subject to change without notice or obligation. Version EUR ITA USA SEA CSA Downloaded by? ? Amateur

22、 Radio Directory Downloaded by? ? Amateur Radio Directory 2 - 1 SECTION 2INSIDE VIEWS CONTROL UNIT MAIN UNIT * : Located underside of this point * : Located underside of this point Q15 Q19 Q20 Q14 V-VCO circuit Main CPU (IC19: HD6433876N) EEPROM* (IC17: X25320SI) PLL IC* IC2 M64076AGP U-VCO circuit

23、UHF FM IF IC* (IC8: TA31136FN) MIC amplifier* (Q88: 2SC4081) PLL reference oscillator (X1: CR-549 15.2 MHz) UHF antenna switch (D27*, D37, D39, D72) UHF 1st mixer (Q42, Q43, D32) VHF antenna switching (D9*, D16, D18) VHF power module* (IC1: M67746) VHF APC DET* (D7, D8: RB706F) VHF RF amplifier (Q16

24、: 3SK166) High/Low control IC (IC5: TA75S01F) VHF 1st mixer (Q15: 3SK166) AF amplifier (IC12: LA4445) VHF FM IF IC* (IC28: TA31136FN) UHF power module* (IC4: SC-1318) UHF APC DET* (D25, D26: RB706F) SUB CPU (IC10: HD6433032SK) T-data buffer amplifier* (Q12: 2SC4081) R-data buffer amplifier* (Q13: 2S

25、A1576) CPU reset IC* (IC11: S-80945ANMP-DD9) LCD controller (IC8: SED1354F0A) CFL drive (Q14, Q15, Q19*, Q20*) 3 - 1 SECTION 3DISASSEMBLY INSTRUCTIONS Removing the MAIN unit q Unscrew 1 screw, A, and remove the cover. w Unplug J4 to separate the fan motor from the MAIN unit. e Remove 2 main shield,

26、B, and TR-A clip, Cin the direc- tion of the arrow. Removing the CONTROL unit q Unscrew 4 screws, A, and remove the cover. w Unplug J5 to separate the speaker and front panel. e Remove rear panel in the deirection of the arrow. r Remove 6 knobs, B. t Unscrew 5 screws, C, and remove the CONTROL unit

27、in the direction of the arrow. y Unscrew 2 screws, D, when remove the LCD. r Unsolder 3 points, D, and unscrew 11 nut, E. t Remove the MAIN unit in the direction of the arrow. A B B C Cover J4 E E E E MAIN UNIT Chassis D A Rear panel J5 Front panel A CONTROL UNIT D D B B LCD C C Downloaded by? ? Ama

28、teur Radio Directory 4 - 1 SECTION 4CIRCUIT DESCRIPTION 4-1 RECEIVER CIRCUITS 4-1-1 DUPLEXER CIRCUIT The transceiver has a duplexer (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 low-pass fil- ter (L15, L16, L7

29、8, C70C72) is for VHF signals and the high- pass filter (L44, L45, L82, C189, C190, C493) is for UHF sig- nals. The separated signals are applied to each RF circuit. 4-1-2 VHF ANTENNA SWITCHING CIRCUIT The antenna switching circuit functions as a low-pass filter while receiving. However, its impedan

30、ce becomes very high while transmitting by turning ON diode (D18). Thus transmit signals are blocked from entering the receiver circuits. The antenna switching circuit employs a 1/4 type diode switch- ing system. The passed signals are then applied to the VHF RF amplifier circuit. 4-1-3 VHF SQUELCH

31、ATTENUATOR CIRCUIT The attenuator circuit attenuates the signal strength to a maximum of 10 dB to protect the RF amplifier from distortion when excessively strong signals are received. The current flow of the antenna switching circuit (D18) is con- trolled by the SQL control via Q33. When the SQL co

32、ntrol is rotated clockwise deeper than 12 oclock, the current of D18 is increased. In this case, D18 acts as an attenuator. 4-1-4 VHF RF CIRCUIT 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 p

33、ass through the tunable bandpass filter (D15, L25, L26, C115C117). The filtered signals are amplified at the VHF RF amplifier (Q16) and are then enter another 3-stage tunable bandpass filter (D11D14, L20L21, C94, C96C105) to suppress unwant- ed signals. and improve the selectivity. The filtered sign

34、als are applied to the VHF 1st mixer circuit (Q15). The tunable bandpass filters (D11D13, D15) employ varac- tor diodes to tune the center frequency of the RF passband for wide bandwidth receiving and good image response rejection. The PLL lock voltage is used for control voltage of these varactor d

35、iodes. The PLL lock voltage is amplified at the DC-amplifier (Q18) and then applied to the CPU (IC19, pin 99). The CPU outputs the control signal to the varactor diodes via the D/A converter (IC3). 4-1-5 VHF 1ST MIXER CIRCUIT The 1st mixer circuit converts the received signal to a fixed frequency of

36、 the 1st IF signal with a 1st LO (V-VCO output) frequency. The signals from the VHF RF circuit are mixed with the 1st LO signal at the 1st mixer circuit (Q15) to produce a 15.65 MHz 1st IF signal. 4-1-6 VHF 1ST IF CIRCUIT By changing the PLL frequency, only the desired frequency will pass through a

37、pair of crystal filters at the next stage of the mixer. The 1st IF signal from the VHF 1st mixer circuit is applied to a pair of crystal filters (FI1) to suppress out-of-band signals via a matching circuit (R61, C88). The filtered signal is ampli- fied at the IF amplifier (Q40) and is then applied t

38、o the VHF 2nd mixer circuit (IC28). 4-1-7 VHF 2ND IF AND DEMODULATOR CIRCUITS 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

39、(IC28) contains the 2nd local oscillator, 2nd mixer, limiter amplifier, quadrature detector, and noise detec- tor circuits, etc. VHF 2nd IF AND DEMODULATOR CIRCUITS Mixer 16 Limiter amp. 2nd IF filter 450 kHz PLL IC IC2 X1 15.2 MHz X2 (15.2 MHz) RSSI IC28 TA31136F 14 1st IF (15.65 MHz) from Q40 VSQL

40、 signal to the CPU pin 97 11109 8753 AF signal VR8V Squelch level adjustment R196 2 1 19 Active filter FI4 (FI5) Noise detector FM detector 4 - 2 The 1st IF signal from the 2nd IF amplifier is applied to the 2nd mixer section of IC28 (pin 16), and is mixed with a 15.2 MHz 2nd LO signal generated by

41、the reference oscillator cir- cuit (X1, IC2) to produce a 450 kHz VHF 2nd IF signal. The 2nd IF signal from the 2nd mixer passes through the 2nd IF filter (FI4) (during wide channel spacing selection, or pass- es through FI5 during narrow channel spacing selection; EUR, ITA versions only), where unw

42、anted signals are suppressed. It is then amplified at the limiter amplifier section (IC28, pin 5) and applied to the FM detector section (X2, IC28, pins 10, 11) for demodulation the 2nd IF signal into AF signals. The FM detector circuit employs a quadrature detection method (liner phase detection),

43、which uses a ceramic dis- criminator (X2) for phase delay to obtain a non-adjusting cir- cuit. The detected signal from IC28 (pin 9) is applied to the AF circuit. 4-1-8 VHF AF AMPLIFIER CIRCUIT The AF amplifier circuit amplifies the detected signals to drive a speaker. The AF circuit includes an AF

44、mute circuit for the squelch. AF signals from FM IF IC (IC28, pin 9) pass through the AF selector (IC21, pins 9, 8), and are then applied to the low- pass (Q83, R370R373, C406C409) and high-pass (Q84, R375R379, C415C418) filters. The filtered signals are level adjusted at the volume control IC (IC10

45、), and are ampli- fied at the AF power amplifier (IC12, pin 2) passing through the V-AF mute switch (Q70). The output signal from IC12 (pin 11) drives the external or internal speaker. 4-1-9 VHF SQUELCH CIRCUIT NOISE SQUELCH A noise squelch circuit cuts out AF signals when no RF sig- nals are received. By detecting noise components in the AF signals, the squelch circuit switches the AF mute switch. Some of the noise components in the AF signals from the FM IF