IC-T7H_serv.pdf

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1、SERVICE MANUAL DUAL BAND FM TRANSCEIVIER INTRODUCTION DANGER ORDERING PARTS REPAIR NOTES This service manual describes the latest service information for the IC-T7H DUAL BAND FM TRANSCEIVER at the time of publication. 4 version of the IC-T7H have been designed. This serves manual cover each versions

2、. NEVER connect the transceiver to an AC outlet or to a DC power supply that uses more than 16 V. This will ruin the transcever. 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

3、 more than 20 dBm (100mW) to the antenna connector. This could damage the transceiv- ers 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 111

4、0002700 S.ICNJM2904M-T1IC-T7H 1F UNIT5pieces 8810008750 Screw PH BO 2 x 15 ZKIC-T7H Chassis10pieces 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 d

5、isconnected from its power source. 3. DO NOT force any of the variable components. 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

6、. DO NOT transmit power into a signal generator or a sweep generator. 7. ALWAYS connect a 40 dB to 50 dB attenuator between the transceiver and a deveiation meter or spectrum analyzer when using such test equipment. 8. READ the instructions of test equipment thoroughly before connecting equipment to

7、 the transceiver. To upgrade quality, all electrical or mechanical parts and internal circuits are subject to change without notice or obligation. MODEL IC-T7H VERSIONSYMBOL Europe Italy SE Asia U.S.A. EUR ITA SEA USA-3 SECTION1SPECIFICATIONS SECTION2INSIDE VIEWS SECTION3DISASSEMBLY INSTRUCTIONS SEC

8、TION4CIRCUIT DESCRIPTION 4 - 1RECEIVER CIRCUITS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4 - 1 4 - 2TRANSMITTER CIRCUITS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4 - 2 4 - 3PLL CIR

9、CUITS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4 - 3 4 - 4POWER SUPPLY CIRCUITS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4 - 4 4 - 5OTHER CIRCUITS . . . . . . . . . . . .

10、 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4 - 4 4 - 6PORT ALLOCATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4 - 5 SECTION5ADJUSTMENT PROCEDURES 5 - 1PLL AND TRANSMITTER ADJUSTMENT . . . .

11、 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5 - 1 5 - 2RECEIVER ADJUSTMENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5 - 3 SECTION6PARTS LIST SECTION7MECHANICAL PARTS AND DISASSEMBLY SECTION8SEMI-CONDUCTOR INFORMATION

12、 SECTION9BOARD LAYOUTS 9 - 1LOGIC UNIT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9 - 1 9 - 22F UNIT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

13、 . .9 - 3 9 - 31F UNIT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9 - 5 SECTION10BLOCK DIAGRAM SECTION11VOLTAGE DIAGRAM TABLE OF CONTENTS SECTION 1SPECIFICATIONS 1 - 1 All stated specifications are subject to change

14、without notice or obligation. Frequency coverage Mode Frequency stability (30 C to +50 C; +32 F to +122 F) Tuning steps Antenna connector External DC power High power Low power Rated audio Power saved (at 9.6 V) Usable temperature range Dimensions (Projections not included) Weight RF output power (a

15、t 13.5 V DC) Modulation system Max. frequency deviation External mic.connector Spurious emissions Receive system Intermediate frequencies Sensitivity Squelch sensitivity Selectivity Spurious and image rejection ratio Audio output power ( at 13.5 V) External speaker connector 144 MHz band430 MHz band

16、 RECEIVERTRANSMITTERGENERAL Tx: 144 MHz148 MHzTx: 430 MHz450 MHz*2 Rx: 118 MHz174 MHz*1Rx: 400 MHz470 MHz*2 144 MHz146 MHz430 MHz440 MHz Tx: 140 MHz148 MHz*1 430 MHz440 MHz Rx: 118 MHz174 MHz*1 136 MHz174 MHz*1400 MHz470 MHz*3 F3 / F2 5 ppm 5, 10, 12.5, 15, 20, 25, 30 or 50 kHz BNC (50 ) 4.5 to 16 V

17、 DC 1.6 A (typical)1.6 A (typical) 0.6 A (typical)0.7 A (typical) 180 mA (typical)190 mA (typical) 16 mA (typical)18 mA (typical) 10 C to +60 C (+14F to +140F) 57(W)110(H) 27(D) mm; 214(W)4516(H) 1116(D) inch (with BP-170) 57(W)122(H) 29(D) mm; 214(W)41316(H) 1532(D) inch (with BP-173/180) 285 g; 10

18、.1 oz (with BP-170 and dry cell batteries) 320 g; 10.8 oz (with BP-180) 405 g; 10.8 oz (with BP-173) High: 6.0 WHigh: 6.0 W Low: 0.5 WLow: 0.5 W Variable reactance frequency modulation 5.0 kHz 3-conductor 2.5 mm (110in) (2 k) Less than 60 dB Double-conversion super heterodyne 1st: 45.150 MHz, 2nd 45

19、0 kHz Less than 0.16 V (typical) for 12 dB SINAD Less than 0.18 V More than 7.5 kHz / 60 dB, Less then 15 kHz / 6 dB More than 60 dBMore than 50 dB (More than 50 dB at 12 IF) More than 500 mW at 10 % distortion with an 8 load 3-conductor 3.5 mm (18in) (8 ) USA-3 Europe SE Asia Italy Current drain (a

20、t 13.5 V) Tx Rx Guaranteed frequency range: *1144 MHz148 MHz, *2440 MHz450 MHz, *3430 MHz440 MHz SECTION 2INSIDE VIEWS LOGIC UNIT AND 2F UNIT 2 - 1 1F UNIT CPU system clock (X1: CR534 5.03MHz) CPU system clock (IC1: M38267M8L-165GP) Speaker Initial matrix Microphone amplifier/lpf (IC2: BA4510F) UHF

21、band pass filter (FI201: EFCH445MWN) UHF RF amplifier* (Q201: 2SC4226) * Located under side of these points AF power amplifier (IC151: 2SC5226) VHF RF amplifier* (Q51: 2SC5226) 1st IF filter (FI401: FL244) 2nd IF filter (FI101: CFWM450E) +3V regulater (IC2: S-81335HG-K) 2F UNITLOGIC UNIT CPU system

22、clock (IC1: M38267M8L-165GP) DUAL VCO board Power amplifier (Q402: 2SK3075) PA board Drive amplifier (Q401: 2SK3074) SECTION 3DISASSEMBLY INSTRUCTIONS 3 - 1 DISASSEMBLING PANELS 1 Unscrew 4 screws, A from the rear panel and 2 screws, B from the rear plate to separate front and rear panels. 2 Unscrew

23、 4 screws, C from the rear plate to remove it. REMOVING LOGIC UNIT 1Unscrew 4 screws, D from the LOGIC Unit. 2Unsolder jumper wires from the speaker as shown below. REMOVING 2F UNIT 1Unscrew 1 screw, E from the 2F unit. 2Unsolder the point, F, then remove the 2F unit with the contact base. (Disconne

24、ct J1 on reverse side of the 2F unit to remove). Rear panel C Front panel Rear panel A A B C Ground lug Front panel Speaker LOGIC unit Unsolder D D 2F unit F E Rear panel Contact base J1 REMOVING 1F UNIT 1Pull the 2 knobs off and then unscrew the nut. 2Unscrew 3 screws, G and 2 screws, H from the 1F

25、 unit. 3 Unsolder 2 points, I then remove the 1F unit. Ground lug Knob 1F unit Nut I H G Rear panel SECTION 4CIRCUIT DESCRIPTION 4 - 1 4-1RECEIVER CIRCUITS 4-1-1DUPLEXER CIRCUIT (1F UNIT) The transceiver has a duplexer (low-pass and high-pass fil- ters) on the first stage from the antenna connector

26、to sepa- rate the signals into VHF and UHF signals. The low-pass fil- ter (L10L12, C16C22) for VHF signals and high-pass filter (L1L3, C1C5) for UHF signals. The separated signals are applied to each RF circuit. 4-1-2VHF ANTENNA SWITCHING CIRCUIT (1F UNIT) The antenna switching circuit functions as

27、a low-pass filter while receiving. However, Its impedance becomes very high while transmitting by applying a current to D51 and D52. 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 a

28、re then applied to the RF amplifier circuit on the 2F unit. 4-1-3VHF RF CIRCUIT (2F UNIT) 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 are applied to the limitter (D55), and are then passed t

29、hrough the band- pass filter (D52, L53). The filtered signal is applied to the RF amplifiers (Q51, Q52). The amplifier consists of a cascade circuit. The amplified signals are passed through the next stage band-pass filter (D53, D54, L54, L55) to suppress unwanted signals. The filtered signals are t

30、hen applied to the mixer circuit (Q401). D53 and D54 track the band-pass filters and are controlled by the PLL lock voltage. These diodes tune the center fre- quency to obtain good image response rejection. 4-1-4UHF RF CIRCUIT (2F UNIT) The signals from the antenna switching circuit (1F unit; D551,

31、D552, D722D724 and Q204) are applied to the limit- ter (D201), and are then amplified at the the RF amplifier (Q201). The amplified signals are passed through the band- pass filter (FI201), and are then applied to another RF ampli- fier (Q202). The amplified signals are applied to the 1st mixer circ

32、uit (Q401). Common circuits with VHF band are used later stage from the 1st mixer. 4-1-51ST MIXER AND 1ST IF CIRCUITS (2F UNIT) The mixer circuit converts the received signal to a fixed fre- quency of the 1st IF signal with a 1st LO (VCO output) fre- quency. By changing the PLL frequency, only the d

33、esired frequency will be passed through a crystal filter at the next stage of the mixer. The received signals from the VHF or UHF RF circuit are mixed with the 1st LO signal (VCO output signal) at the 1st mixer (Q401) to produce a 45.15 MHz 1st IF signal. The 1st IF signal is applied to a crystal fi

34、lter (FI401) to sup- press out-of-band signals. The filtered 1st IF signal is ampli- fied at the IF amplifier (Q101) and is then applied to the 2nd mixer circuit (IC101, pin 16). 4-1-62ND IF AND DEMODULATOR CIRCUITS (2F UNIT) The 2nd mixer circuit converts the 1st IF signal to a 2nd IF signal. A dou

35、ble superheterodyne system (which converts receive signals twice) improves the image rejection ratio and obtains stable receiver gain. The FM IF IC (IC101) contains the 2nd mixer, 2nd local oscillator, limiter amplifier, S-meter detector and quadrature detector circuits. 2nd IF AND DEMODULATOR CIRCU

36、ITS Mixer 16 Limiter amp. 2nd IF filter 450 kHz PLL IC IC851 X1 15.2 MHz RSSI IC2 TA31136FN 13 2nd IF (45.15 MHz) from Q101 (1F unit) SD signal to the CPU pin 3 (Logic unit: IC1) 11109 87532 1716 Active filter FI101 Noise detector FM detector Noise comp. NOISE signal to the CPU pin 12 (Logic unit: I

37、C1) 12 C107 C115 R112 C501 C112 C111 C113 R104 L21 AF signal DETO to the LOGIC unit 3 Q356 2nd local oscillator C116 R113 R106 L102 R111 R112 LO signal from Q852 on the LOGIC unit 1F unit 2F unit 4 - 2 The 1st IF signal (45.15 MHz) from the IF amplifier (Q101) is applied to the 2nd mixer section of

38、IC101 (pin 16), and is mixed with the 2nd LO signal (45.6 MHZ) for conversion to a 450 kHz 2nd IF signal at the 2nd mixer section. The 2nd IF signal (450 kHz) from the 2nd mixer section (IC101, pin 3) passes through the ceramic filter (FI101) where unwanted signals are suppressed. It is then amplifi

39、ed at the limiter amplifier section (IC101, pin 5) and applied to the quadrature detector section to demodulate the 2nd IF signal into AF signals. AF signals output from IC101 (pin 9) are applied to the AF drive amplifier (Q12) on the LOGIC unit. The S-meter out- put “SD” signal from IC101 (pin 12)

40、is applied to the CPU (LOGIC unit; IC1, pin 3). 4-1-7AF AMPLIFIER CIRCUIT (LOGIC UNIT) The AF amplifier circuit, including an AF mute switch, ampli- fies the demodulated signals to drive a speaker. The demodulated AF signals (“DETO” signals) from the FM IF IC (IC101) on the 2F unit are applied to th

41、e drive amplifi- er (Q12, pin 3) via the band-pass filter (C44, C45). The band-pass filter suppresses subaudible tones and higher noise signal components. The amplified signals from Q12 (pin 1) pass through the AF mute switch (Q10) and are then applied to the AF volume control on the 1F unit via the

42、 “AF” signal line. 4-1-8AF POWER AMPLIFIER CIRCUIT (2F UNIT) The AF signals from the AF volume control (“AFV” signals) are amplified at the AF power amplifier IC (IC151, pin4). The amplified AF signals are applied to the loud speaker via the external speaker jack (1F unit; J902). 4-1-9NOISE SQUELCH

43、UNIT (2F UNIT) A noise squelch circuit cuts out AF signals when no RF sig- nal is 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 IC (IC101, pin 9) are applied to the active filt

44、er section (IC101, pins 7 and 8). The variable register (R504) adjusts the active filter input level. The active filter section amplifies noise components with fre- quencies of 20 kHz and above. The filtered signals are rec- tified at the noise detector section and converted into “NOlSE” (pulse type

45、) signals at the noise comparator sec- tion. The “NOISE” signal is applied to the CPU (LOGIC unit; IC1, pin 12). The CPU (LOGIC unit; IC1) detects the signal level from the number of the pulses, and outputs an “MM/RM” signal from IC1 pin 44 on LOGIC unit. This signal controls the AF mute switch (LOG

46、IC unit; Q10) to cut the AF signal line. 4-2TRANSMITTER CIRCUITS 4-2-1MICROPHONE AMPLIFIER CIRCUIT (LOGIC AND 2F UNIT) The microphone amplifier circuit amplifies audio signals with +6 dB/octave pre-emphasis from the microphone to a level needed for the modulation circuit. The AF signals from the bui

47、lt-in condenser microphone (LOGIC unit; MC1), or from the MIC Jack (1F unit; J901) via the “EXT MIC” line are applied to the limiter amplifier (LOGIC unit; IC12, pin 3) which has +6 dB/octave pre- emphasis characteristics. The amplified AF signals pass through the splatter filter (IC12, pins 57). Th

48、e filtered signals are applied to frequen- cy deviation pots (2F unit; R308 for VHF, R314 for UHF) and are then applied to the modulation circuit on the DUAL VCO board. Q32 on the LOGIC unit is the PTT control circuit and outputs a “High” signal to the CPU when transmitting. 4-2-2MODULATION CIRCUIT

49、(DUAL VCO BOARD) The modulation circuit modulates the VCO oscillating signal (RF signal) using the microphone audio signals. The “VMOD” signals change the reactance of a diode (D304) to modulate the oscillated signal at the VHF-VCO cir- cuit (Q304, Q305 and D303). The “UMOD” signals are applied to the UHF-VCO circuit via the “USHIFT” line. The applied signals change the reac- tance of a diode (D302) to modulate the oscillated signal at the UHF-VCO circuit (Q301, Q302 and D301). The VCO output is buffer-amplified at Q306 and then applied to the band switch (D351 and D352) via the L