Kenwood TH-K20A Service Manual
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Kenwood TH-K20A Service Manual

144mhz fm transceiver
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144MHz FM TRANSCEIVER
TH-K20A/K20E
SERVICE MANUAL
Helical antenna
M: (T90-1018-35)
K,E: (T90-1044-15)
Knob (Volume)
(K29-9503-03)
T
his product complies with the RoHS directive for the European market.
Knob(Encoder)
(K29-9504-03)
Key top (16 keys)
(K29-9502-02)
Plastic cabinet assy
(A02-4158-03)
© 2009-1 PRINTED IN JAPAN
© 2011-11 PRINTED IN JAPAN
B51-8281-00 ( N ) 1219
B51-8997-00 ( Y ) 203
When performing the TH-K20 adjustment, a personal
computer, programming interface and tuning software are
required.
CONTENTS
DISASSEMBLY FOR REPAIR .....................2
CLONE MODE .............................................3
CIRCUIT DESCRIPTION .............................4
SEMICONDUCTOR DATA ...........................7
COMPONENTS DESCRIPTION ..................9
PARTS LIST ...............................................10
EXPLODED VIEW ......................................16
PACKING ...................................................17
ADJUSTMENT ...........................................18
TX-RX UNIT (X57-821X-XX) ...................22
SCHEMATIC DIAGRAM ............................26
BLOCK DIAGRAM .....................................30
LEVEL DIAGRAM ......................................32
BT-16 (Battery Case) .............................33
PB-46L (Li-ion Battery Pack) ................33
SPECIFICATIONS ......................................35
This product uses Lead Free solder
.

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  • Page 1: Table Of Contents

    144MHz FM TRANSCEIVER TH-K20A/K20E SERVICE MANUAL © 2009-1 PRINTED IN JAPAN © 2011-11 PRINTED IN JAPAN B51-8281-00 ( N ) 1219 B51-8997-00 ( Y ) 203 When performing the TH-K20 adjustment, a personal computer, programming interface and tuning software are required.

  • Page 2: Disassembly For Repair

    Copyright 2011 by JVC KENWOOD Corporation. All While every precaution has been taken in the preparation rights reserved. of this manual, JVC KENWOOD Corporation assumes no No part of this manual may be reproduced, translated, responsibility for errors or omissions. Neither is any liability...

  • Page 3: Clone Mode

    TH-K20A/K20E DISASSEMBLY FOR REPAIR 3. Removing the Rear Panel 1. Raise the rear panel on the chassis ( k ). Antenna terminal CLONE MODE Programming data can be transferred from one trans- Note: ceiver to another by connecting them via their SP/MIC con- •...

  • Page 4: Circuit Description

    TH-K20A/K20E CIRCUIT DESCRIPTION 1. Frequency Confi guration The PLL circuit in the transmitter generates the neces- sary frequencies. 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.
  • Page 5 TH-K20A/K20E CIRCUIT DESCRIPTION 2-3. IF Amplifi er Circuit 3. Transmitter System The fi rst IF signal is passed through a four-pole mono- 3-1. Microphone Amplifi er Circuit lithic crystal fi lter (XF200) to remove the adjacent channel The signal from microphone amplifi ed by IC301 and goes signal.
  • Page 6 TH-K20A/K20E CIRCUIT DESCRIPTION 4. Frequency Synthesizer Circuit Realign the transceiver after replacing the EEPROM. 4-1. Frequency Synthesizer The frequency synthesizer consists of the TCXO (X1), 6. Signaling Circuit VCO, PLL IC (IC1) and buffer amplifi ers. 6-1. Encode The TCXO generates 19.2MHz. The frequency stability is 5.0 ppm within the temperature range of –30 to +60°C.

  • Page 7: Semiconductor Data

    TH-K20A/K20E SEMICONDUCTOR DATA MCU: R5F2L3ACCKEKA (TX-RX unit IC401) Pin No. Port Name Function [MONI] key switch input Pin No. Port Name Function MONI L: Active KEYIT Type detection Common serial clock output KEYIS Type detection DATA Common serial data output...
  • Page 8 TH-K20A/K20E SEMICONDUCTOR DATA PLL IC: MB15E03SL-E1 (TX-RX unit IC1) D/A Converter IC: R2A20178NP (TX-RX unit IC300) Pin No. Port Name Function Programmable reference divider Pin No. Port Name Function OSCIN input Vin2 FROM AF fi lter signal input OSCOUT Oscillator output Power supply voltage (5.0V)

  • Page 9: Components Description

    TH-K20A/K20E COMPONENTS DESCRIPTION TX-RX unit (X57-821X-XX) Ref. No. Use/Function Operation/Condition/Compatibility Power supply Ref. No. Use/Function Operation/Condition/Compatibility Q304 Active ON (5MSC: L) (5MS) switch PLL system Frequency control Speaker mute Q305 for AF signal line Active ON 2nd mixer, IF amplifi er, FM...

  • Page 10: Parts List

    TH-K20A/K20E PARTS LIST 2 2 0 CC45 Color* 010 = 1pF 0 = 22pF 1 = Type ... ceramic, electrolytic, etc. 4 = Voltage rating 100 = 10pF 2 = Shape ... round, square, etc. 5 = Value 101 = 100pF Multiplier 3 = Temp.
  • Page 11 CC73HCH1H050C CHIP C 5.0PF CC73GCH1H220J CHIP C 22PF X57-8210-12 TX-RX UNIT (FOR SERVICE) C101 CC73HCH1H220J CHIP C 22PF X57-8210-21 TX-RX UNIT (FOR SERVICE) X57-8212-72 TX-RX UNIT (FOR SERVICE) C102 CK73HB1H102K CHIP C 1000PF M: TH-K20A(M) K : TH-K20A(K) E : TH-K20E(E)
  • Page 12 CHIP C 1000PF C231 CC73HCH1H050C CHIP C 5.0PF C351,352 CK73HB1H102K CHIP C 1000PF C232 CC73HCH1H101J CHIP C 100PF C353 CK73HB1C473K CHIP C 0.047UF C233 CK73HB1H102K CHIP C 1000PF C354 CK73HB1H102K CHIP C 1000PF M: TH-K20A(M) K : TH-K20A(K) E : TH-K20E(E)
  • Page 13 SMALL FIXED INDUCTOR (10UH) RK73HB1J100J CHIP R 1/16W L40-1285-71 SMALL FIXED INDUCTOR (120NH) M: TH-K20A(M) If a part reference number is listed in a shaded box, that part does not come with the PCB. K : TH-K20A(K) E : TH-K20E(E)
  • Page 14 RK73HB1J104J CHIP R 100K 1/16W R372 RK73HB1J473J CHIP R 1/16W R241 RK73HB1J184J CHIP R 180K 1/16W R374 RK73HB1J103J CHIP R 1/16W R243 RK73HB1J105J CHIP R 1.0M 1/16W R376 RK73HB1J000J CHIP R 1/16W M: TH-K20A(M) K : TH-K20A(K) E : TH-K20E(E)
  • Page 15 RB521S-30 DIODE D304 RB521S-30 DIODE D305 DZ2S068(M) ZENER DIODE D401 DZ2S036(0) ZENER DIODE M: TH-K20A(M) If a part reference number is listed in a shaded box, that part does not come with the PCB. K : TH-K20A(K) E : TH-K20E(E)

  • Page 16: Exploded View

    TH-K20A/K20E EXPLODED VIEW Cx13 S418 MIC300 J301 J300 VR300 TX-RX unit S419 A : N09-2438-05 B : N80-2606-43 C : N83-2005-48 Parts with the exploded numbers larger than 700 are not supplied. If a part reference number is listed in a box on the exploded view of the PCB, that part does not come with the PCB.

  • Page 17: Packing

    56 HELICAL ANTENNA (T90-1018-35): M 61 CHARGER (W08-1249-35) 37 PACKING FIXTURE (H12-4324-02): K 42 Belt clip (J29-0756-05) 41 ITEM CARTON CASE M: TH-K20A(M) (H52-2486-02): K K: TH-K20A(K) E: TH-K20E(E) Parts with the exploded numbers larger than 700 are not supplied.

  • Page 18: Adjustment

    TH-K20A/K20E ADJUSTMENT Note: Required Test Equipment • When performing the TH-K20 adjustment, a personal 1. Stabilized Power Supply computer, programming interface cable (KPG-22A/22U), 1) The supply voltage can be changed between 3V and 16V tuning cable (E30-3216-05) and tuning software (MCP-5T) and the current is 3A or more.
  • Page 19 TH-K20A/K20E ADJUSTMENT Frequency and Signaling Preparations for Tuning the Transceiver The transceiver has been adjusted for the frequencies Before attempting to tune the transceiver, connect the shown in the following table. When required, re-adjust them unit to a suitable power supply.
  • Page 20 TH-K20A/K20E ADJUSTMENT Common Section Measurement Adjustment Item Condition Specifi cations / Remarks Test- Unit Terminal Unit Parts Method equipment 1. Setting 1) BATT terminal voltage: 7.5V 2) SSG standard modulation [Wide] MOD: 1kHz, DEV: 3kHz [Narrow] MOD: 1kHz, DEV: 1.5kHz 2.
  • Page 21 TH-K20A/K20E ADJUSTMENT Measurement Adjustment Item Condition Specifi cations / Remarks Test- Unit Terminal Unit Parts Method equipment 7. Battery 1) BATT terminal voltage: 7.1V Power TX-RX ANT Check Segment display: 4 dots Detection PTT: ON meter BATT Check TX Power: Low...

  • Page 22: Pc Board

    TH-K20A/K20E PC BOARD TX-RX UNIT (X57-821X-XX) 0-11: K 0-20: M 2-71: E Component side view (J79-0325-09) J79-0325-09 D415 D419 D418 D416 D421 D420 D423 D422 C412 C411 25 26 D417 R425 R447 C415 CN30 CN304 D425 D424 R451 MODE RESE D414 Ref.
  • Page 23 TH-K20A/K20E PC BOARD TX-RX UNIT (X57-821X-XX) 0-11: K 0-20: M 2-71: E Component side view (J79-0325-09) D415 R366 R443 C372 MIC300 C383 R379 IC307 C344 C421 IC308 Q306 D304 C352 C367 D302 C358 R378 C360 R367 IC306 Q300 R357 C305...
  • Page 24 TH-K20A/K20E PC BOARD TX-RX UNIT (X57-821X-XX) 0-11: K 0-20: M 2-71: E Foil side view (J79-0325-09) S417 S418 MONI C141 C139 C137 L115 L113 C134 C138 L109 C136 L214 L112 C265 R119 D104 C146 D203 C261 R243 C154 R319 C318...
  • Page 25 TH-K20A/K20E PC BOARD TX-RX UNIT (X57-821X-XX) 0-11: K 0-20: M 2-71: E Foil side view (J79-0325-09) C108 C105 R107 R444 L104 C148 C147 R103 C113 R101 C101 R111 C102 C109 C112 C110 R115 L113 C115 C382 Q103 C150 C155 Q307...

  • Page 26: Schematic Diagram

    TH-K20A/K20E SCHEMATIC DIAGRAM TX-RX UNIT(X57-821X-XX) R431 X57-8210-XX D408 D409 R431 R432 R433 0-20 DA2S101 R432 0-20 0-11 R433 DA2S101 0-11 DA2S101 2-71 2-71 DA2S101 5MSC D40 4 KEYO4 S401 S402 S403 S404 D408-D411 1SS388F D408 Key matrix D 40 5...
  • Page 27 TH-K20A/K20E SCHEMATIC DIAGRAM TX-RX UNIT (X57-821X-XX) SHIFT SHIFT SHIFT THERM THERM THERM CURRENT LSDI VDCSW VOLCS 5MSC SEG15 SEG15 SEG14 VOLCS SEG14 SEG13 VDCSW SEG13 CURRENT R331 SEG12 CURRENT SEG12 VDCSW SEG11 SEG11 SEG10 SEG10 R332 SEG9 BATT SEG9 SEG8...
  • Page 28 TH-K20A/K20E SCHEMATIC DIAGRAM TX-RX UNIT (X57-821X-XX) SHIFT THERM 0.70V FREQUENCY MCH3914(7)-H RF SWITCH MODULATOR CONTROL 1.80V 2SC5108(Y)F RF AMP HSC277 220n 1SV325F R:1.03V 0.5p T:1.74V 2SC5636 RF BUFFER RXLO HSC277 4.15V 0.022u D1,2 FREQUENCY CONTROL D 11 D7,8 TX/RX SW...
  • Page 29 TH-K20A/K20E SCHEMATIC DIAGRAM TX-RX UNIT (X57-821X-XX) D101 L109 L110 FINAL HVC131 Q103 C138 C136 C140 L113 L114 L115 L107 C134 D102 DRIVE RD07MUS2BT112 Q102 1000p HVC131 C113 1000p R116 RFM01U7P RXLO Hi:1.48V Hi:1.49V Mid:1.27V Mid:1.28V Lo:1.21V D101,102,103,104 Temp compensation Lo:1.21V...

  • Page 30: Block Diagram

    TH-K20A/K20E BLOCK DIAGRAM TX-RX UNIT (X57-821x-xx ) D426 B30-1782-05 MB15A02PFV2E1 PLPS BUSY DCSW LEDG PLLE LTC014EEBFS8 PLL SYSTEM (GRN) Q403 MCH3914(7)-H PLLD LTC014EEBFS8 INVERT D1,D2 1SV325F D427 3.3V B30-1779-05 LOOP FILTER DCSW LEDR HVC350B TCXO 2SC5383-T111 19.2MHz (RED) Q404 LTC014EEBFS8...
  • Page 31 TH-K20A/K20E BLOCK DIAGRAM RX: 136.000~173.995MHz (K,M,E) TX: 136.000~173.995MHz (M) 144.000~147.995MHz (K) 144.000~145.995MHz (E) D103-D105 RN1425 Q102 Q103 D101,D102 D7,D8 Q101 2SC5108(Y)F RFM01U7P RD07MUS2BT112 HVC131 2SC5636 HSC277 2SC4926YD TX/RX FINAL DRIVE BUFF ANT SW DRIVE F101 0.5A TH101 RIPPLE 2SC5383-T111 CURRENT...

  • Page 32: Level Diagram

    TH-K20A/K20E LEVEL DIAGRAM...

  • Page 33: Optional Accessories

    TH-K20A/K20E OPTIONAL ACCESSORIES BT-16 (Battery Case (6AAA/LR03)) KNB-65L (Li-ion Battery Pack) ■ External View ■ External View ■ Specifi cations Voltage ................7.4V Battery capacity ..........typ 1520mAh min 1460mAh EMC-11 (Clip Microphone with Earphone) KVC-22 (DC Vehicular Chager Adapter) ■...
  • Page 34 TH-K20A/K20E MEMO...

  • Page 35: Specifications

    TH-K20A/K20E SPECIFICATIONS General Guaranteed range (MHz) TX & RX 144~148 (K/M) / 144~146 (E) 136~174 (M) / 144~148 (K) / 144~146 (E) Operation Frequency range (MHz) 136~174 Mode F3E, F2D Antenna impedance 50 Operating temperature range –20°C ~ +60°C (+4°F ~ +140°F) Operating Voltage DC 6.0 ~ 9.0V (7.4V nominal)
  • Page 36 TH-K20A/K20E...
  • Page 37 TH-K20A/K20E TH-K20A/K20E PC BOARD PC BOARD TX-RX UNIT (X57-821X-XX) 0-11: K 0-20: M 2-71: E TX-RX UNIT (X57-821X-XX) 0-11: K 0-20: M 2-71: E Component side view (J79-0325-09) Component side view (J79-0325-09) J79-0325-09 D415 R366 R443 D419 D418 C372 MIC300...
  • Page 38 TH-K20A/K20E TH-K20A/K20E PC BOARD PC BOARD TX-RX UNIT (X57-821X-XX) 0-11: K 0-20: M 2-71: E TX-RX UNIT (X57-821X-XX) 0-11: K 0-20: M 2-71: E Foil side view (J79-0325-09) Foil side view (J79-0325-09) S417 S418 MONI C108 C105 R107 R444 L104...
  • Page 39 TX-RX UNIT(X57-821X-XX) SHIFT SHIFT SHIFT SHIFT D101 L109 L110 THERM THERM THERM THERM RF SWITCH MODULATOR FREQUENCY MCH3914(7)-H 0.70V FINAL CURRENT CONTROL HVC131 1.80V Q103 2SC5108(Y)F L114 L115 C134 D102 C136 C138 C140 R431 X57-8210-XX D408 D409 R431 R432 R433 RF AMP HSC277 DRIVE...
  • Page 40 TX-RX UNIT (X57-821x-xx ) RX: 136.000~173.995MHz (K,M,E) TX: 136.000~173.995MHz (M) 144.000~147.995MHz (K) D426 144.000~145.995MHz (E) B30-1782-05 MB15A02PFV2E1 PLPS BUSY DCSW LEDG PLLE LTC014EEBFS8 PLL SYSTEM D103-D105 (GRN) Q403 RN1425 MCH3914(7)-H LTC014EEBFS8 PLLD INVERT Q102 Q103 D1,D2 D101,D102 D7,D8 Q101 2SC5108(Y)F RFM01U7P RD07MUS2BT112 HVC131...

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