TH-K20A_E_serv.pdf

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1、 2009-1 PRINTED IN JAPAN B51-8281-00 (N) 1219 144MHz FM TRANSCEIVER TH-K20A/K20E SERVICE MANUAL This product uses Lead Free solder.This product complies with the RoHS directive for the European market. 2011-11 PRINTED IN JAPAN B51-8997-00 (Y) 203 CONTENTS DISASSEMBLY FOR REPAIR .2 CLONE MODE .3 CIRC

2、UIT DESCRIPTION .4 SEMICONDUCTOR DATA .7 COMPONENTS DESCRIPTION .9 PARTS LIST .10 EXPLODED VIEW .16 PACKING .17 ADJUSTMENT .18 PC BOARD TX-RX UNIT (X57-821X-XX) .22 SCHEMATIC DIAGRAM .26 BLOCK DIAGRAM .30 LEVEL DIAGRAM .32 OPTIONAL ACCESSORIES BT-16 (Battery Case) .33 EMC-11 (Clip Microphone with Ea

3、rphone) .33 PB-46L (Li-ion Battery Pack) .33 KVC-22 (DC Vehicular Chager Adapter) .33 SPECIFICATIONS .35 Helical antenna M: (T90-1018-35) K,E: (T90-1044-15) Plastic cabinet assy (A02-4158-03) Knob (Volume) (K29-9503-03) Knob(Encoder) (K29-9504-03) Key top (16 keys) (K29-9502-02) When performing the

4、TH-K20 adjustment, a personal computer, programming interface and tuning software are required. TH-K20A/K20E 2 Document Copyrights Copyright 2011 by JVC KENWOOD Corporation. All rights reserved. No part of this manual may be reproduced, translated, distributed, or transmitted in any form or by any m

5、eans, electronic, mechanical, photocopying, recording, or other- wise, for any purpose without the prior written permission of JVC KENWOOD Corporation. Disclaimer While every precaution has been taken in the preparation of this manual, JVC KENWOOD Corporation assumes no responsibility for errors or

6、omissions. Neither is any liability assumed for damages resulting from the use of the informa- tion contained herein. JVC KENWOOD Corporation reserves the right to make changes to any products herein at any time for improvement purposes. DISASSEMBLY FOR REPAIR 1. Separating the Case Assembly from th

7、e Chassis 1. Remove the two knobs (a). 2. Remove the two screws (b). 3. Pull off the cap from SP/MIC jack (c). 4. Expand the right and left sides of the bottom of the case assembly, Iift the chassis, and remove it from the case assembly (d). 5. Taking care not to cut the speaker lead wire with conne

8、c- tor (e), open the chassis and case assembly. b b a a c d 2. Removing the TX-RX unit from the Chassis 1. Remove the packing (f). 2. Remove the 13 screws (g). 3. Remove the packing (h) and two hexagon nuts (i). 4. Remove the solder from the antenna terminal using a soldering iron then lift the unit

9、 off (j). Note: When reassembling the unit in the chassis, be sure to solder the antenna terminal. e Red Black TH-K20A/K20E 3 3. Removing the Rear Panel 1. Raise the rear panel on the chassis (k). k CLONE MODE Programming data can be transferred from one trans- ceiver to another by connecting them v

10、ia their SP/MIC con- nectors. Cloning can copy the transceiver data to another trans- ceiver even without the use of a personal computer. The following data cannot be cloned. Tuning data 1. Connect the cloning cable (part No. E30-3410-05) to the SP/MIC connectors on the source and target transceiv-

11、ers. 2. Turn the source and target transceiver power OFF. 3. Turn the source transceiver power ON while pressing the CALL keys, to enter clone mode. ”CLONE” appears on the display. 4. Turn the target transceiver power ON. 5. Press the CALL key on the source transceiver while ”SEND” is displayed. The

12、 data of the source is sent to the target. While the target is receiving data, ”RECV” appears on the display. When cloning is completed, the ”END” appears on the source and target display. 6. Turn the source and target transceiver power OFF. Note: The Model name and Market codes must be the same in

13、order to clone the transceiver. If a data transfer error occurs during Clone mode, ”ER- ROR” appears on the target transceiver. When you turn the target transceiver power ON again while ”ERROR” is displayed, the target transceiver performs a full reset. At this time, the source transceiver continues

14、 to send data. DISASSEMBLY FOR REPAIR Antenna terminal f g h i j i Cloning cable (E30-3410-05) TH-K20A/K20E 4 1. Frequency Confi guration The receiver utilizes double conversion. The first IF is 38.85MHz and the second IF is 450kHz. The fi rst Local os- cillator is supplied from the PLL circuit. The

15、 PLL circuit in the transmitter generates the neces- sary frequencies. Fig. 1 Frequency confi guration Fig. 2 Receiver system 2. Receiver System The receiver system is shown in Figure 2. 2-1. RF Amplifi er Circuit The signal coming from the antenna passes through the transmit/receive switching diode

16、 circuit (D101, D102,D103,D104 and D105) and a BPF (L213,L214), and is then amplifi ed by the RF amplifi er (Q204). The resulting signal passes through a BPF (L209,L211 and L217) and goes to the mixer. These BPFs are adjusted by variable capacitors (D200,D201 and D204). The input voltage to the vari

17、able capacitor is a regulated voltage out- put from the DAC (IC300). 2-2. First Mixer The signal from the front end is mixed with the fi rst local oscillator signal generated in the PLL circuit by Q203 to pro- duce a fi rst IF frequency of 38.85 MHz. The resulting signal passes through the XF200 MCF

18、 to cut the adjacent spurious and provide the optimum charac- teristics, such as adjacent frequency selectivity. RX: 136173.995MHz(K,E,M) 174.85 212.845MHz 1st MIXMCFSP MIC CF 450kHz ANT ANT SW RF AMP IF SYSTEM X2 doubler PLL VCO 38.85MHz 38.4MHz TX AMP T/R SW AF AMP MIC AMP AF filter TCXO19.2MHz RF

19、 AMP TX: 136173.995MHz(M) 144147.995MHz(K) 144145.995MHz(E) 1st Lo: TX: 136173.995MHz(M) 144147.995MHz(K) 144145.995MHz(E) SP ANT IC200 IF,MIX,DET Q203 1st MIX IC303 CF200 ANT SW Q201 doubler 2nd Local X1 TCXO 19.2MHz BPF BPF Q204 RF AMPXF200 MCF Q202 IF AMP IC307 AF PA BPF1st Local BPFAFfilterVR300

20、 CIRCUIT DESCRIPTION RatingItem Nominal center frequency (fo) Pass bandwidth Attenuation bandwidth Ultimate attenuation70dB or more (fo 900 kHz) Spurious response 1dB or lessRipple Insertion loss Terminating impedanc610? / 3pF MCF (L71-0669-05) characteristics (TX-RX unit XF200) Nominal center frequ

21、ency (fo) 3dB bandwidth 50dB bandwidth 3.0kHz) of (Ripple Guaranteed attenuation50dB or more (fo 100kHz) Insertion loss I/O matching impedance Ceramic filter (L72-1042-05) characteristics (TX-RX unit CF200) 5dB or less 11.0kHz or less 38.850MHz 450kHz 6dB or less 1.5k? ItemRating 40dB or more (fo +1

22、MHz) 25.0kHz or less at 45dB 5.0kHz or more at 3dB 4.5kHz or more 2dB or less TH-K20A/K20E 5 3. Transmitter System 3-1. Microphone Amplifi er Circuit The signal from microphone amplifi ed by IC301 and goes through mute switch (IC300). IC304 is composed of high-pass fi lter, low-pass fi lter and pre-

23、emphasis/IDC circuit. The output signal from the DAC IC (IC300) goes to the VCO modulation input. Fig. 3 Microphone amplifi er circuit 3-2. Driver and Final Amplifi er Circuit The signal from the T/R switch (D8 is on) is amplifi ed by the pre-drive amplifi er (Q101) to 30mW. The output of the pre-dr

24、ive amplifi er is amplifi ed by the drive amplifi er (Q102) and the RF fi nal amplifi er (Q103) to 5.5W (1W when the power is low). The drive amplifi er and the RF fi nal amplifi er consist of two MOS FET stages. The output of the RF final amplifier is then passed through the harmonic fi lter (LPF)

25、and antenna switch (D101 and D102) and is applied to the antenna terminal. CIRCUIT DESCRIPTION X1 TCXO VCO LSDO IC300MIC DAC AMP/LIM IC304 MIC IC301 MOD AMP MIC Q3,D4 ANT FINAL AMP ANT SW From T/R SW (D8) D101,102 +B POWC Q102 DRIVE AMP Q101 VDD VG Pre-DRIVE Q103 R125 R127 R129 CURDET Fig. 4 Drive a

26、nd fi nal amplifi er circuit 2-3. IF Amplifi er Circuit The fi rst IF signal is passed through a four-pole mono- lithic crystal fi lter (XF200) to remove the adjacent channel signal. The fi ltered fi rst IF signal is amplifi ed by the fi rst IF ampli- fi er (Q202) and then applied to the lF system I

27、C (IC200). The IF system IC provides a second mixer, second local oscillator, limiting amplifier, quadrature detector and RSSI (Received Signal Strength Indicator).The second mixer mixes the fi rst IF signal with the 38.4MHz of the second lo- cal oscillator output (TCXO: X1) and produces the second

28、IF signal of 450kHz. The second IF signal is passed through the ceramic fi lter (CF200) to remove the adjacent channel signal. The fi ltered second IF signal is amplified by the limiting amplifier and demodulated by the quadrature detector with the ceramic discriminator (CD200).The demodulated signa

29、l is routed to the audio circuit. 2-4. Audio Amplifi er Circuit The demodulated signal from IC200 is amplified by IC303, IC302 and goes to AF amplifi er through IC307. The signal then goes through a volume control (VR300), and is routed to an audio power amplifi er (IC307) where it is amplifi ed and

30、 output to the speaker. To output sounds from the speaker, IC401 sends a high signal to the SPMUT line and turns IC401 on through Q301, Q302, Q303, Q305 and Q306. TH-K20A/K20E 6 CIRCUIT DESCRIPTION Realign the transceiver after replacing the EEPROM. 6. Signaling Circuit 6-1. Encode CTCSS/ DCS The CT

31、CSS and DCS signals are output from pin 49 (LSDO) of the MCU (IC401). The signal passes through a low-pass CR fi lter. The signal is mixed with the audio signal and goes to the VCO and TCXO (X1) modulation input after signal processing in the DAC IC (IC300). DTMF The DTMF signal is output from pin 5

32、0 (HSDO) of the MCU. The signal passes through a low-pass CR fi lter. TX devia- tion making an adjustment by MCU is applied to the DAC IC (IC300). The signal is mixed with the audio signal and goes to the VCO and TCXO. 6-2. Decode CTCSS/DCS The output signal from IF IC (IC200) enters the MCU (IC401)

33、 through IC300. IC401 determines whether the CTCSS or DCS matches the preset value, and controls the SPMUT and the speaker output sounds according to the squelch results. Fig. 6 Encode 7. Power Supply There are fi ve 5V power supplies for the MCU: 5M is always output while the power is on. 5C is a c

34、ommon 5V and is output when SAVE is not set to ON. 5R is 5V for reception and output during reception. 5T is 5V for transmission and output during transmission. 5MS is 5V for the SP/MIC connector and the DAC IC (IC300). 4. Frequency Synthesizer Circuit 4-1. Frequency Synthesizer The frequency synthe

35、sizer consists of the TCXO (X1), VCO, PLL IC (IC1) and buffer amplifi ers. The TCXO generates 19.2MHz. The frequency stability is 5.0 ppm within the temperature range of 30 to +60C. The frequency tuning and modulation of the TCXO are done to apply a voltage to pin 1 of the TCXO. The output of the TC

36、XO is applied to pin 1 of the PLL IC. The VCO consists of 1VCO and covers a dual range of the 144.00174.00MHz and the 182.85212.85MHz. The VCO generates 182.85212.85MHz for providing to the fi rst local signal in receive. The PLL IC consists of a prescaler, reference divider, phase comparator, charg

37、e pump (The frequency step of the PLL circuit is 5 or 6.25 kHz). PLL data is output from DAT (pin 19), CLK (pin 18) and PLDL (pin 20) of the MCU (IC401). The data are input to the PLL IC when the channel is changed or when transmission is changed to reception and vice versa. A PLL lock condition is

38、always monitored by the pin 22 (PLUL) of the MCU. When the PLL is unlocked, the PLUL goes low. Fig. 5 PLL block diagram 5. Control Circuit The control consists of the MCU (IC401) and its peripheral circuits. It controls the TX-RX unit. IC401 mainly performs the following; 1) Switching between transm

39、ission and reception by PTT signal input. 2) Reading channel information, frequency, and program data from the memory circuit. 3) Sending frequency program data to the PLL. 4) Controlling squelch on/off via the DC voltage from the squelch circuit. 5) Controlling the audio mute circuit via the decode

40、 data input. 6) Transmitting tone and encode data. 7) Sending display data to the LCD assembly. Note: The EEPROM stores tuning data (Deviation, Squelch, etc.). HSDO LSDO IC401 MCU IC300 DAC AF POWER AMP TCXO 3 4 7 8 FREQ VCO 12 MOD 9 BEEP 6 24 CTCSS/DCS INV VCO PLL MCU IC401 DAT,CLK,PLLE IC1 PLLD 8

41、1 5 14 RF SW LPFTo mixer LSDO Q4 BUFF Q5 TCXO X1 SW To Pre-AMP SHIFT (TX: Low) D8 D7 Q6 CV AMP Q3 LD AMP TXRX TXRX TH-K20A/K20E 7 SEMICONDUCTOR DATA MCU: R5F2L3ACCKEKA (TX-RX unit IC401) Pin No.Port NameI/OFunction 1KEYITIType detection 2KEYISIType detection 3HSDOODTMF/BEEP/1750Hz tone output 4LSDOO

42、CTCSS/DCS tone output 5WKUPO-Ground 6VREF-Reference voltage input 7MODE-MCU mode select 8XCIN-Not used (Pull-up) 9XCOUT-Not used 10RESETIMCU reset 11XOUTO11.0592MHz MCU clock output 12VSS-Ground 13XINI11.0592MHz clock input for MCU 14VCC-5V power supply (5M) 15BSFTOBeat shift control 16INPTTI INT PT

43、T switch input L: Active 175RCO 5R RX power switch control L: Active 18,19ENC2-ENC1IEncoder input 2,1 20RxDISerial data input from PC 21TxDOSerial data input to PC 22W/NO Wide/Narrow control H: Narrow 23PLLEO PLL-IC enable H: Active 24PLPSO PLL-IC save control L: Save ON 25PLLDI PLL unlock detect L:

44、 Unlock 26EXPTTI EXT-PTT input L: Active 27LAMPO BacKlight LED control H: Lights 28NCONot used 29E2PCSO EEPROM chip select L: Active 30E2PINIData input from EEPROM 31-34COM0-COM3O LCD common output H: Active 35-66SEG0-SEG31O LCD segment output H: Active 67LEDRO TX LED (Red) control H: Lights 68LEDGO

45、 BUSY LED (Green) control H: Lights 695VCO 5V MIC AMP power switch control L: Active 705MSCO 5MS main power switch control L: Active 71SPMO Speaker mute control L: Mute Pin No.Port NameI/OFunction 72MONII MONI key switch input L: Active 73CLKOCommon serial clock output 74DATAOCommon serial data outp

46、ut 755CCO 5C Common power switch control L: Active 765TCO 5T TX power switch control L: Active 77VOLCSO DAC-IC chip select L: Active 78VDCSWO Voltage discharge control H: Active 79CURRENTITX current detect 80VOXIVOX level detect 81REMI Remote control microphone key detect 82BATTIBattery voltage dete

47、ction 83THERMITemperture detect 84RSSIIRSSI level detect 85SQLISquelch level detect 86LSDIICTCSS/DCS tone detect 87CVDETIVCO controle voltage detect 88-90 KEYO4- KEYO2 OKey matrix output 4-2 91-93VL1-VL3-LCD drive power supply 94SHIFTO VCO TX/RX control H: TX 95KEYO1OKey matrix output 1 96VL4-LCD drive power supply 97-100KEYI1-KEYI4IKey matrix input 1-4 TH-K20A/K20E 8 FM IC: TA31136FNG (TX-RX unit IC200) Pin No.Port NameI/OFunction 1OSCINI2nd Local oscillator input 2OSCOUTO2nd Local oscillator output 3MIXOUTOMIX output 4VCC-Power supply (5.0V) 5IFINI2nd IF input and decoupling 6