Kenwood-THK-4-Service-Manual电路原理图.pdf
430MHz FM TRANSCEIVERTH-K4AT/K4E© 2003-9 PRINTED IN JAPANB51-8660-00 (S) 497SERVICE MANUALDISASSEMBLY FOR REPAIR . 2CIRCUIT DESCRIPTION . 6SEMICONDUCTOR DATA . 14COMPONENTS DESCRIPTION . 15PARTS LIST . 17EXPLODED VIEW. 23PACKING . 25ADJUSTMENT . 27TERMINAL FUNCTION . 43PC BOARDTX-RX UNIT (X57-675X-XX) (A/3) . 44TX-RX UNIT (X57-675X-XX) (B/3),(C/3) . 48CONTENTSSCHEMATIC DIAGRAM. 50LEVEL DIAGRAM . 55BLOCK DIAGRAM . 56BC-21 (WALL CHARGER) . 58PB-43N (Ni-MH BATTERY PACK) . 58BT-14 (BATTERY CASE) . 59PG-4Y (PROGRAMMING INTERFACE CABLE) . 59MCP-1A (MEMORY CONTROL PROGRAM) . 59SPECIFICATIONS . BACK COVERKnob (ENC)(K29-5159-03)Knob (VOL)(K29-5150-03)Cabinet assy(16key)(A02-3822-23)Helical Antenna(T90-1019-25)Key top (16key)(K29-9272-02)Front glass(B10-2746-03)Knob(PTT/LAMP/MON)(K29-9274-03)Knob (ENC)(K29-5159-03)Knob (VOL)(K29-5150-03)Cabinet assy(4key)(A02-3823-23)Helical Antenna(T90-1019-25)Key top (4key)(K29-9276-02)Front glass(B10-2746-03)Knob(PTT/LAMP/MON)(K29-9274-03)TH-K4AT TH-K4ECap(SP/MIC/DC IN)(B09-0675-03)Cap(SP/MIC/DC IN)(B09-0675-03)TH-K4AT/K4E2DISASSEMBLY FOR REPAIRHow to remove the case assembly from thechassis1. Remove two screws (z) holding the chassis.2. Pull out two knobs (x) and remove two round nuts (c).3. Pull out the SP and MIC parts of the cap from jacks (v).4. Turn the unit over with the bottom of the chassis facingupwards, and remove the chassis (n) from the caseassembly (b).5. Remove the speaker lead (m) from the connector (CN2) ofthe TX-RX PC board (TX-RX unit A/3).How to remove the PC board Numeric key PC board (TX-RX unit B/3)1. Remove three screws (,) on the numeric key PC board.2. Lift the numeric key PC board and remove it from theconnector (CN9) of the TX-RX PC board (.). PTT PC board (TX-RX unit C/3)3. Remove one screw on the PTT PC board (/).4. Pull the PTT PC board to the left and remove it from theconnector (CN6) of the TX-RX PC board (TX-RX unit A/3)(). TX-RX PC board (TX-RX unit A/3)5. Remove the SP/MIC jack cover ().6. Remove two screws (ç) holding the shieldcover (antenna terminal section).7. Remove two screws () holding the shieldcover (final amplifier section).8. Remove eight screws () on the TX-RX PCboard.9. Absorb solder from the antenna terminal ()with a solder absorber.Note: Do not melt the shadow plate (µ) whenmoving the tip of the solder absorber closeto the antenna terminal.10. Remove the TX-RX PC board from the chassis, then removethe encoder volume FPC () from the flat cable connectorof the TX-RX PC board.CN2CN9CN6xxccvmb,.çµ/nzTX-RX unit (B/3)TX-RX unit (C/3)TX-RX unit (A/3)TH-K4AT/K4E3DISASSEMBLY FOR REPAIRSoldering the antenna terminal1. With the shield cover removed from the antenna terminalsection, install two screws on the PC board and bring thePC board into contact with the chassis (z).2. Solder the antenna terminal with a soldering iron (x).3. Remove the two screws installed in step 1 above, and installthe two screws again on the PC board together with theshield cover (c).Replacing the final FET (Q12)1. Remove the two screws holding the shield cover of thefinal FET section (z).2. Remove solder from the shield cover completely with asolder absorber.3. Remove the shield cover (x).zxczx4. Apply the tips of soldering irons to all the four pins of the finalFET at the same time (c), heat them sufficiently, and removethe final FET (v). (Two persons should be required to do this.)5. Remove all PC boards from the chassis.6. Confirm that there is no space between the radiation plateinstalled on the foil side of the TX-RX PC board (TX-RX unitA/3) and the PC board (b). If there is any space betweenthe radiation plate and PC board, eliminate it by applyingthe tip of the soldering iron to the radiation plate.7. Apply the tip of the soldering iron to the installation side of theradiation plate of the TX-RX PC board, put a little amount ofsolder to the radiation plate that is seen through a square holein the final FET installation section and melt the solder (n).8. When the solder in step 7 is melted, place the final FET onthe PC board by aligning it with the silk of the final FETinstallation section of the PC board (m).9. Release the soldering iron and confirm that the final FETand radiation plate have been soldered.10. Solder the four pins of the final FET with the soldering iron.11. Install all the PC boards.12. Reinstall the shield cover removed in step 3 above in itsoriginal position and install two screws.13. Solder the shield cover to the PC board.14. Install the chassis on the case assembly and assemble them.15. Readjust transmission power.Note: Since the FET is sensitive to static electricity, alwayswear a grounding band. Use a highly insulated ceramicheater solder iron.Radiation plateTX-RX PC boardbcvmnThis illustration isM2 type.TH-K4AT/K4E4Special care and attention required for assembly1. Gluing to the key top (MIC element section)You must also glue on the speaker storage area and heapthe glue up until wealthy glued on the speaker storage areaand the key top for waterproofing the MIC element side ofthe key top. (Fig. 1)Fig. 12. Bending the LCD hardware fixture (J21-8456-03) tabs(1)Insert the tabs of the LCD hardware fixture into four holesin the LCD installing position of the TX-RX PCB (TX-RX unitA/3). (Fig. 2)Heap the glue up until wealthy glued on the speakerstorage area and the key top (MIC element section).Fig. 2(2)By pressing the LCD hardware fixture from the componentside of the TX-RX PCB, you must bent all 4 tabs of the LCDhardware fixture being visible from the foil side until thebases of each tabs are folded at least 45 degrees (Fig. 3). Ifthe bending angle of the tabs of the LCD hardware fixtureis less than 45 degrees, a display error may occur.Bending positionNGNGMin 45degrees3. PTT PCB (TX-RX unit C/3) installation procedureInstalling the PTT PCB on the TX-RX PCB and chassis areas follows:(1)Insert the PTT PCB connector (CN7) into the TX-RX PCBconnector (CN6) lightly.(2)Push three parts of the PTT PCB to contact tightly with thechassis. There may be a small gap between the connectors.(Fig. 4)Note: A double-side adhesive tape (J99-0376-04) is usedbehind the PTT switch. When reassembling the PTTPCB to the chassis, press the PTT PCB (under the PTTswitch) so that the tape hold the PCB and chassissecurely.Fig. 3CN6ChassisPTT switchPTT PCB (C/3)OKA bitclearanceNoclearanceNGCN6CN7CN7ChassisPTT PCB (C/3)PTT switchFig. 4Push three parts of the PTT PCBto contact tightly with the chassis.(3)Tighten one screw in the PTT PCB.DISASSEMBLY FOR REPAIRTH-K4AT/K4E5DISASSEMBLY FOR REPAIR4. Packing (G53-1572-02) TX/BUSY lamp installationprocedure(1)To assure waterproofing, install the packing in the chassisgroove as shown in Fig. 5. (z)(2)Install the packing TX/BUSY lamp section on the chassis.(x)zxOKPackingNGPackingChassisChassis5. Packing (G53-1572-02) bottom installation procedure(1)Before installing the numeric key PCB (TX-RX unit B/3) onthe chassis, push three parts of the packing to contact tightlywith the chassis as shown in Fig. 6. If the packing is not incontact with the chassis, there may be a gap between thetransceiver bottom case assembly and the battery, andwater may enter through the gap.Fig. 5OK NGPush three parts of the packing tocontact tightly with the chassis.Clearance NGFig. 66. Cautions for installing the chassis on the case assembly(1)Verify that the packing (G53-1572-02) TX/BUSY lamp sectionis has been past through the hole in the illumination guidesection on the top of the case assembly. (Fig. 7)LAMPLOWPTTFig. 7(2)Align the speaker lead as shown fig.8. Do not place theleads over the key top section, LCD section or SP/MIC/DCIN cap section.Do not fix this part of thekey top to the rib of thecase assembly.7. Cautions for installing the key top on the case assembly(1)Install the key top keypad section and the power switchsection on the rib of the case assembly.(2)Do not fix the part between the key top keypad section andthe power switch section to the rib of the case assembly,but install it as shown in Fig. 8.The packing TX/BUSY lamp section is hasbeen past through the hole in the illuminationguide section on the top of the case assembly.Fig. 8TH-K4AT/K4E6CIRCUIT DESCRIPTIONFrequency ConfigurationThe frequency configuration is shown in Figure 1 andTable 1.Fig. 1 Frequency configuration361.150431.145MHz(M2)391.150401.145MHz(E)400.000469.995MHz(M2)430.000439.995MHz(E)400.000469.995MHz(M2)430.000439.995MHz(E)TX/RX :ANTSWMCF38.85MHz38.4MHz12.8MHz450kHzCFMIX, IF,DETAFAMPSPPREDRIVEFINALTCXODRIVETriplerx 3RFAMP1st MIXPLLVCOMICAMPMICANTReceiver System Front EndThe received signal from the antenna passes through a low-pass filter and then through a transmission/reception switchingcircuit (antenna switch) and enters the band-pass filter (L40,L41, L38).The signal passing through the band-pass filter (L40, L41,L38) is amplified by with an RF amplifier (Q17), passes througha band-pass filter (L32, L34) and enters the first mixer (Q16).These band-pass filters are tuned to a desired frequencyby varicaps (D21, D20, D19, D18).A tuning voltage corresponding to the desired signal isapplied to each varicap through the BPF/APC terminal (pin 6)of the MPU (IC8) to tune to the receive frequency.Double super heterodyneReception method 1st IF Frequency 38.85MHz (Lower)2nd IF Frequency 450kHz (Lower)Transmission method VCO direct oscillation amplificationModulation Variable reactance phase modulationTable 1 Basic configurationANTSWSPLPFVCOBPF/APCMPUIC8PLLIF AMP,DETTriplerx 3TCXOBPFL41,L40,L38BPFL32,L34MIXERQ161st Local OSC(PLL)RF AMPQ17ANTMCFXF1IF AMPQ24FM ICIC3Q232nd Local OSCX1AF AMPIC65R5RD20D21LV6Tuning voltageD18D1938.85MHz12.8MHz First MixerThe received signal passing through the band-pass filter(L32, L34) is mixed with the first local signal generated by theVCO by the first mixer (Q16) to produce a first IF signal (38.85MHz) (Lower heterodyne).The first IF signal passes through a MCF (Monolithic crystalfilter: XF1) to remove unwanted components.The first IF signal passing through the MCF (XF1) is amplifiedby an IF amplifier (Q24) and the resulting signal enters the FMIC (IC3).Fig. 2 Receiver section configurationItem RatingNominal center frequency (fo) 38.85MHzPass bandwidth ±6.0kHz or more at 3dBAttenuation bandwidth ±25kHz or less at 35dBUltimate attenuation 70dB or more (fo 910 kHz)Spurious response 40dB or more (fo +1MHz)Ripple 1dB or lessInsertion loss 4dB or lessTerminating impedance 610 ±5% / 3pF ±0.5pFTable 2 MCF (L71-0619-05) characteristics (TX-RX unit XF1)Item RatingNominal center frequency (fo) 450kHz3dB bandwidth ±6.5kHz or more50dB bandwidth ±15.5kHz or lessRipple 2dB or less (fo ±6.5kHz)Guaranteed attenuation 55dB or more(fo ±18kHz to ±33kHz)50dB or more (fo ±100kHz)Insertion loss 4dB or lessI/O matching impedance 1.5kTable 3 Ceramic filter (L72-0968-05) characteristics (TX-RX unit CF1)TH-K4AT/K4E7CIRCUIT DESCRIPTION IF CircuitThe first IF signal (38.85 MHz) amplified by the IF amplifier (Q24)and the second IF signal (38.4 MHz) generated by tripling the 12.8MHz reference oscillator frequency of the TCXO (X1) by Q23, aremixed in the FM IC to produce a second IF signal (450 kHz) (Lowerheterodyne).The second IF signal passes through a ceramic filter (CF1)to remove unwanted components.The second IF signal passing through the ceramic filter (CF1)passes through the IF amplifier in the FM IC again and isdetected to produced an audio signal. Squelch and Mute CircuitA noise component is obtained by passing FM detectionoutput (FM IC pin 9) through an operational amplifier in theCF1450kHzCD1AF OUTAFMSMSQIC8MPU49948SMVSQV16 15 14 13 12 11 10 91 2 3 4 5 6 7 8MIXLocalOSCBufferRSSIQuadraturedetectorLPFNoiseAMPIF AMPInverterAMP1st IF input(38.85MHz)IC3FM IC2nd local OSC(38.4MHz)5RQ21AF FILTERQ20AF MUTESWITCHVOL INR135C173 C174R125R126NoisecompRectifier5RSPAF OUTAFFILTERQ21AF MUTESWITCHQ20IC6AF AMPIC3FM ICVR201AF VOLUMEDTMF/BEEPREMIC8MPUSPKAFOSPGREM/TXD40469J4SP JACKFig. 3 IF, Squelch, Mute and S meter circuitFig. 4 AF amplifierFM IC and band-pass filter consisting of R125, R126, R135,C173, C174. The noise component is rectified in the FM IC toproduce a DC voltage, which is output from the N-REC terminal(pin 14) of the FM IC as squelch voltage.The squelch voltage enters the SQ terminal (pin 48) of theMPU (IC8) and is compared with the reference voltage presetin the MPU to control audio signal ON/OFF.When “L“ is output from the AFM terminal (pin 9) of the MPU,the AF mute switch (Q20) is activated to mute the audio signal. S Meter CircuitThe S meter voltage is output from the RSSI terminal (pin12) of the FM IC (IC3) and input to the SM terminal (pin 49) ofthe MPU. Then the voltage is converted from analog to digitalin the MPU to control the S meter display on the LCD. AF AmplifierThe detected audio signal passes through an AF filter (Q21)and enters an AF mute switch (Q20).After passing through the AF mute switch (Q20), the signalpasses through an AF volume (VR201) and is amplified to aspecified output level with an AF amplifier (IC6).The audio signal amplified with the AF amplifier (IC6) isoutput through an internal speaker or an external speakerjack (J4).The beep tone and the DTMF signal are output from theDTMF/BEEP terminal (pin 40) of the MPU (IC8), enters the AFamplifier (IC6) and is output as a monitor tone.TH-K4AT/K4E8CIRCUIT DESCRIPTIONTransmitter System Microphone Amplifier CircuitThe audio signal from the microphone passes through ahigh-pass filter (IC5) and enters a microphone amplifier (IC16).The signal passes through a pre-emphasis circuit, limiteramplifier and splatter filter inside the microphone amplifier.The splatter filter will remove distortion outside the audio band. Modulation CircuitThe audio signal amplified by the microphone amplifier(IC16) passes through a semi-fixed volume (VR5) formodulation adjustment, and goes to the VCO modulationvaricap (D6) for variable reactance phase modulation. Drive and Final CircuitThe output signal from VCO (Q1) passes through an RFamplifier (Q2, Q5, Q9) and drive amplifier (Q10, Q11), and isamplified by a power amplifier (Q12). Transmission/Reception Switching CircuitThe signal amplified by the power amplifier (Q12) passesthrough a transmission/recep
