IC-T2H_SM.pdf

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1、144 MHz FM TRANSCEIVER iC-t2h iC-t2e-t INTRODUCTION This service manual describes the latest service information for the IC-T2H/E-T 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. Such a connection coul

2、d cause a fire hazard and/or electric 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 transce

3、ivers front end. ORDERING 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 1140006560 S.ICHD6433875A45H IC-T2H MAIN UNIT 1 piece 8810009560 Screw

4、B0 2 6 ZKIC-T2H CHASSIS6 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

5、of the variable components. Turn them slowly and smoothly. 4. DO NOT short any circuits or electronic parts. An insulated 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 swe

6、ep generator. 7. ALWAYS connect a 40 dB or 50 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 transciver. To upgrade quality, all electrical or me

7、chanical parts and inter- nal circuits are subject to change without notice or obligation. MODEL VERSION SYMBOL Europe U.K. Italy U.S.A. Thailand Taiwan IC-T2H IC-T2E-T USA EUR UK ITA C.S. America/-1 CSA/-1 THA TWN AsiaSEA Asia-1ANI TABLE OF CONTENTS SECTION 1 SPECIFICATIONS SECTION 2INSIDE VIEWS SE

8、CTION3 DISASSEMBLY INSTRUCTIONS SECTION 4CIRCUIT DESCRIPTION 4 - 1 RECEIVER CIRCUITS . 4 1 4 - 2 TRANSMITTER CIRCUITS . 4 2 4 - 3 PLL CIRCUIT. 4 3 4 - 4 POWER SUPPLY CIRCUITS . 4 3 4 - 5 CPU PORT ALLOCATIONS . 4 4 SECTION 5ADJUSTMENT PROCEDURES 5 - 1 PREPARATION. 5 1 5 - 2 PLL AND TRANSMITTER ADJUST

9、MENTS. 5 2 5 - 3 RECEIVER ADJUSTMENT . 5 3 SECTION 6PARTS LIST SECTION 7 MECHANICAL PARTS AND DISASSEMBLY SECTION 8SEMI-CONDUCTOR INFORMATION SECTION 9 BOARD LAYOUTS SECTION 10 BLOCK DIAGRAM SECTION 11 VOLTAGE DIAGRAM 1 - 1 SECTION 1SPECIFICATIONS IGENERAL Frequency coverage: Guaranteed frequency ra

10、nge: *144148 MHz Mode: FM (F2, F3) Current drain (at 9.6 V DC): Transmitat 6.0 W1.6 A (typical) at 5.0 W1.5 A (typical) Thailand at 1.0 W0.7 A (typical) Receivemax. audio210 mA (typical) power saved25 mA (typical) standby80 mA (typical) Frequency stability: 10 ppm (0C to +50C; 32F to 122F) Usable te

11、mperature range: 10C to 60C; 14F to 140F Antenna connector: BNC (50 ) No. of memory channels: 43 ch (40 regulator, 2 scan edges and 1 call) Acceptable power supply: 9.6 V DC (supplied Ni-Cd cells; negative ground) Frequency resolution: 5 kHz and 12.5 kHz Dimensions (Projections not included) : 58(W)

12、 140.5(H) 32.3(D) mm; 2932(W) 51732(H) 1932(D) inch Weight (with BP-199): 420 g; 14.8 oz ITRANSMITTER Output power (9.6 V DC): 6 W typical (high) 5 W typical (high)Thailand only 0.7 W typical (low) Modulation system: Variable reactance frequency modulation Max. frequency deviation: 5 kHz Spurious em

13、issions: Less than 60 dB External microphone connector: 3-conductor 2.5 (d) mm (110”) 2 k IRECEIVER Receive system: Double conversion superheterodyne Intermediate frequencies: 1st30.85 MHz 2nd450 kHz Sensitivity(12 dB SINAD): Less than 0.18 V (122 dBm) Squelch sensitivity (threshold): Less than 0.18

14、 V (122 dBm) Selectivity: More than 15 kHz/6 dB Less than 30 kHz/60 dB Spurious and image refection ratio: 60 dB (typical) (except 2nd IF image frequency) Audio output power (at 9.6 V DC): 500 mW (typical at 10% distortion with an 8 load) External speaker connector: 3-conductor 3.5 (d) mm (18”) 8 Al

15、l stated specifications are subject to change without notice or obligation. U.S.A. Europe, U.K. Thailand Italy, Asia, ANI, C.S.A. Taiwan 140.000150.000 MHz* 144.000146.000 MHz 136.000174.000 MHz* 145.000146.000 MHz 136.000174.000 MHz* 144.000146.000 MHz 136.000174.000 MHz* 145.000146.000 MHz Version

16、TransmitReceive 2 - 1 SECTION 2INSIDE VIEWS MAIN UNIT TOP VIEWBOTTOM VIEW Low-pass filter circuit RF amplifier (Q12: 2SK360IG) Analog switch* (IC4: BU4066BCFV) *below the mic. PLL IC (IC1: PD3140GS) 1st mixer circuit (Q13: 2SK360IG) FM IF IC (IC2: TA31136FN) Power amplifier (Q1: 2SK3075) EEP ROM (IC

17、7: X25040S1-2.7) TX/RX switching (D3, D4: MA77) Antenna switching circuit (D8, D32: HVU131TRF) Crystal filter (FI1: FL-251 30.85 MHz) VCO circuit Current detector circuit Microphone amplifier IC (IC3: NJM2902V) PLL reference oscillator (X1: CR514 15.2 MHz) CPU (IC8) APC control circuit 3 - 1 SECTION

18、 3DISASSEMBLY INSTRUCTIONS Removing the chassis panel q Unscrew 1 nut, A, and remove 1 nob, B. w Unscrew 2 screws, C. e Remove the the chassis in the direction of the arrow. r Unplug J6 to separate front panel and chassis. Removing the MAIN unit q Unsolder 2 points, D, and unscrew 1 nut, E. w Unscre

19、w 2 screws, F, and 6 screws, G(silver, 2 mm), to separate the chassis and MAIN unit. e Remove the MAIN unit in the direction of the arrow. Chassis C(nickel, 2 mm) 2 J6 (Speaker connector) Front panel ANut BNob F(black, 2 mm) 2 G G MAIN unit ENut Chassis GG G D G(silver, 2 mm) 6 MAIN UNIT (Top view)

20、chassis panel 4 - 1 SECTION 4CIRCUIT DESCRIPTION 4-1 RECEIVER CIRCUITS 4-1-1 ANTENNA SWITCHING CIRCUIT Received signals passed through the low-pass filter (L1L3, C1C7). The filtered signals are applied to the /4type antenna switching circuit (D8, D32, L15, L16, C76C78). The antenna switching circuit

21、 functions as a low-pass filter while transmitting. However, its impedance becomes very high while D8 and D32 are turned ON. Thus transmit signals are blocked from entering the receiver circuits. The antenna switching circuit employs a /4type diode switching system. The passed signals are then appli

22、ed to the RF amplifier cir- cuit. 4-1-2 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 pass through a bandpass filter (D10, L26) after being amplified at the RF amplifier (Q29). The

23、filtered signals are amplified at another RF amplifier (Q12), then applied to the 1st mixer circuit after out-of-band signals are suppressed at the bandpass filter (D11, D12, L18, L19, C92, C94, C96, C236). D10D12 employ varactor diodes that track the bandpass fil- ters and are controlled by the T4/

24、PWR signal from the CPU (IC8, pins 5459). These diodes tune the center frequency of an RF passband for wide bandwidth receiving and good image response rejection. 4-1-3 1ST MIXER AND 1ST IF CIRCUITS The 1st mixer circuit converts the received signal to a fixed frequency of the 1st IF signal with a P

25、LL output frequency. By changing the PLL frequency, only the desired frequency will pass through a crystal filter at the next stage of the 1st mixer. The signals from the RF circuit are mixed at the 1st mixer (Q13) with a 1st LO signal coming from the VCO circuit to produce a 30.85 MHz 1st IF signal

26、. The 1st IF signal is applied to a crystal filter (FI1) to suppress out-of-band signals. The filtered 1st IF signal is applied to the IF amplifier (Q14), then applied to the 2nd mixer circuit (IC2, pin 16). 4-1-4 2ND IF AND DEMODULATOR CIRCUITS The 2nd mixer circuit converts the 1st IF signal to a

27、2nd IF signal. A double conversion superheterodyne system (which converts receive signal twice) improves the image rejection ratio and obtains stable receiver gain. The 1st IF signal from the IF amplifier is applied to the 2nd mixer section of the FM IF IC (IC2, pin 16), and is mixed with the 2nd LO

28、 signal to be converted to a 450 kHz 2nd IF sig- nal. The FM IF IC contains the 2nd mixer, limiter amplifier, quad- rature detector and active filter circuits. A 30.4 MHz 2nd LO signal is produced at the PLL circuit by doubling its reference frequency. The 2nd IF signal from the 2nd mixer (IC2, pin

29、3) passes through a ceramic filter (FI2) to remove unwanted hetero- dyned frequencies. It is then amplified at the limiter amplifier (IC2, pin 5) and applied to the quadrature detector (IC2, pins 10, 11) to demodulate the 2nd IF signal into AF signals. 4-1-5 AF CIRCUIT The AF amplifier circuit ampli

30、fies the demodulated AF signals to drive a speaker. AF signals from the FM IF IC (IC2, pin 9) are applied to the analog switch (IC4, pin 1) via the AF filter circuit (IC3b, pins 6, 7). The output signals from pin 11 are applied to the AF power amplifier (IC5, pin 4) after passing through the VOL con

31、trol (VR board, R1). 2nd IF AND DEMODULATOR CIRCUITS Mixer 16 Limiter amp. 2nd IF filter 450 kHz PLL IC IC1 X1 15.2 MHz IC2 TA31136F 13 1st IF from the IF amp. NOIS signal to the CPU pin 19 11109 8753 AF signal DET R5 SD signal to the CPU pin 98 X3 Squelch level adjustment pot R92 2 1716 Active filt

32、er FI2 Noise detector RSSI TriggerFM detector 12 2 4 - 2 The AF signals from the VOL control are applied to the AF power amplifier circuit (IC5, pin 4) to obtain the specified audio level. The amplified AF signals, output from pin 10, are applied to the internal speaker (SP1) via the SP jack when no

33、 plug is connected to the jack. 4-1-6 SQUELCH CIRCUIT A squelch circuit cuts out AF signals when no RF signals are received. By detecting noise components in the AF signals, the squelch switches the analog switch. A portion of the AF signals from the FM IF IC (IC2, pin 9) are applied to the active f

34、ilter section (IC2, pin 8) where noise components are amplified and detected with an internal noise detector. The squelch input level adjustment pot (R92) is connected in parallel to the active filter input (pin 8) to con- trol the input noise level. The trigger circuit converts the detected signals

35、 to a HIGH or LOW signal and applies this (from pin 13) to the CPU (IC8, pin 19) as the NOIS signal. When the CPU receives a HIGH level NOIS signal, the CPU controls the RMUT line to cut the AF signals at the analog switch IC (IC4). At the same time, the AFON line controls the AF regulator circuit (

36、Q15, Q16) to cut out the VCC power source for the AF power amplifier (IC5). 4-2 TRANSMITTER CIRCUITS 4-2-1 MICROPHONE AMPLIFIER CIRCUIT The microphone amplifier circuit amplifies audio signals with +6 dB/octave pre-emphasis characteristics from the micro- phone to a level needed for the modulation c

37、ircuit. The AF signals from the microphone are applied to the micro- phone amplifier circuit (IC3c, pin 10). The amplified AF sig- nals are passed through the low-pass filter circuit (IC3d, pins 13, 14) via the analog switch (IC4, pins 2, 3). The filtered AF signals are applied to the modulator circ

38、uit after passing through the analog switch (IC4, pins 8, 9) and the deviation adjustment pot (R119). 4-2-2 MODULATION CIRCUIT The modulation circuit modulates the VCO oscillating signal (RF signal) using the microphone audio signal. The audio signals (SHIFT) change the reactance of D6 to modulate a

39、n oscillated signal at the VCO (Q7, Q8). The oscil- lated signal is amplified at the buffer-amplifiers (Q4, Q6), then applied to the T/R switching circuit (D3, D4). 4-2-3 DRIVE/POWER AMPLIFIER CIRCUITS The signal from the VCO circuit passes through the T/R switching circuit (D3) and is amplified at

40、the buffer (Q3), drive (Q2) and power (Q1) amplifiers to obtain 5.5 W (4.5 W: Thailand only) of RF power (at 9.6 V DC/typical). The ampli- fied signal passes through the antenna switching circuit (D1), and low-pass filter (L1L3, C1C7) and is then applied to the antenna connector (J1). The bias curre

41、nt of the drive (Q2) and power (Q1) amplifiers is controlled by the APC circuit to stabilize the output power. 4-2-4 CURRENT DETECTOR CIRCUIT The current detector circuit (Q9, Q28, R161) detects total dri- ving current of the drive and the power amplifiers, using the current sensor (R161). The diffe

42、rential amplifier (Q9) detects voltage differences between the current sensor input and output voltages, then outputs control voltage to the APC cir- cuit. APC circuit Q1 Power amp. Q2 Driver amp. IC3a 3 1 2 T5 VCC Q9Q28 R161 RF signal from PLL to antenna T4 TXC Q37 S5 Current detector circuit APC c

43、ontrol circuit Analog switch (IC4) MIC signal DET signal to the VCO circuit for modulation R5C R5 MMUT signal RMUT signal to the VOL control 1 2 3 4 5 68 9 10 11 12 13 to pins 9, 10 via IC3d from IC3d 4 - 3 4-2-5 APC CIRCUIT The APC circuit (IC3a, Q37) protects drive and power ampli- fiers from exce

44、ssive currents and selects HIGH or LOW out- put power. The output voltage from the current detector circuit is applied to the inverting amplifier (IC3a, pin 2), and the T4/PWR sig- nal from the CPU (IC8, pins 5459) is applied to the other input for reference. When the driving current increases, the

45、input voltage of the differential amplifier (Q9, pin 1) will be decreased. In such cases, input voltage of the inverting amplifier (pin 2) is increased to decrease the output power. Q37 is controlled by the TXC signal from the CPU (IC8, pin 50) to select HIGH or LOW output power. 4-3 PLL CIRCUIT A P

46、LL circuit provides stable oscillation of the transmit fre- quency and receive 1st LO frequency. The PLL output com- pares the phase of the divided VCO frequency to the refer- ence frequency. The PLL output frequency is controlled by the divided ratio (N-data) of a programmable divider. The PLL circ

47、uit contains the VCO circuit (Q7, Q8, D6). The oscillated signal is amplified at the buffer-amplifiers (Q5, Q6) and then applied to the PLL IC (IC1, pin 2). The PLL IC contains a prescaler, programmable counter, pro- grammable divider, phase detector and charge pump, etc. The entered signal is divided at the prescaler and program- mable counter section by the N