Kenwood-THK-2-Service-Manual电路原理图.pdf

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1、144MHz FM TRANSCEIVERTH-K2AT/K2E/K2ET 2003-8 PRINTED IN JAPANB51-8658-00 (S) 836SERVICE MANUALDISASSEMBLY FOR REPAIR . 2CIRCUIT DESCRIPTION . 6SEMICONDUCTOR DATA . 14COMPONENTS DESCRIPTION . 15PARTS LIST . 17EXPLODED VIEW. 23PACKING . 25ADJUSTMENT . 27TERMINAL FUNCTION . 43PC BOARDTX-RX UNIT (X57-67

2、4X-XX) (A/3) . 44TX-RX UNIT (X57-674X-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 . BA

3、CK COVERKnob (ENC)(K29-5159-03)Knob (VOL)(K29-5150-03)Cabinet assy(16key)(A02-3819-23)Helical Antenna(T90-1018-25)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)(A02-3818-23)Helical Antenna(T90-1018-2

4、5)Key top (4key)(K29-9276-02)Front glass(B10-2746-03)Knob(PTT/LAMP/MON)(K29-9274-03)TH-K2AT/K2ET TH-K2ECap(SP/MIC/DC IN)(B09-0675-03)Cap(SP/MIC/DC IN)(B09-0675-03)TH-K2AT/K2E/K2ET2DISASSEMBLY FOR REPAIRHow to remove the case assembly from thechassis1. Remove two screws (z) holding the chassis.2. Pul

5、l 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

6、 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

7、 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 () holding the shieldcover (antenna terminal section).7. Remove two screws () hold

8、ing 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 () whenmoving the tip of the solder absorber closeto the antenna terminal.10. Remove the TX-RX PC board

9、from the chassis, then removethe encoder volume FPC () from the flat cable connectorof the TX-RX PC board.CN2CN9CN6xxccvmb,./nzTX-RX unit (B/3)TX-RX unit (C/3)TX-RX unit (A/3)TH-K2AT/K2E/K2ET3DISASSEMBLY FOR REPAIRSoldering the antenna terminal1. With the shield cover removed from the antenna termin

10、alsection, 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).Replaci

11、ng 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. (E and E3 types only)3. Remove the shield cover (x).zxczx4. Apply the tips of soldering irons to all the four pins of the final

12、FET 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

13、 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 rad

14、iation 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

15、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 th

16、e PC board. (E and E3 typesonly)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 boardbcvmnTH-K2

17、AT/K2E/K2ET4DISASSEMBLY FOR REPAIRSpecial 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 oft

18、he 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

19、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

20、 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)

21、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 t

22、ape 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.TH-K2AT/K2E/K2ET5DISASSEMBLY FOR REPAIR4. Packi

23、ng (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)Befo

24、re 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 ente

25、r 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

26、 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 c

27、ase 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 ha

28、sbeen past through the hole in the illuminationguide section on the top of the case assembly.Fig. 8TH-K2AT/K2E/K2ET6CIRCUIT DESCRIPTIONFrequency ConfigurationThe frequency configuration is shown in Figure 1 andTable 1.Fig. 1 Frequency configuration174.850212.845MHz(K,K2,M,M2)182.850184.845MHz(E,E3)1

29、44.000147.995MHz(K,K2)136.000173.995MHz(M,M2)144.000145.995MHz(E,E3)136.000173.995MHz(K,K2,M,M2)144.000145.995MHz(E,E3)144.000147.995MHz(K,K2)136.000173.995MHz(M,M2)144.000145.995MHz(E,E3)RX :TX :ANTSWMCF38.85MHz38.4MHz12.8MHz450kHzCFMIX, IF,DETAFAMPSPPREDRIVEFINALTCXODRIVETriplerx 3RFAMP1st MIXPLLV

30、COMICAMPMICANTReceiver 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 am

31、plified by with an RF amplifier (Q17), passes througha band-pass filter (L32, L35) and enters the first mixer (Q16).These band-pass filters are tuned to a desired frequencyby varicaps (D21, D20, D19, D18).Double super heterodyneReception method 1st IF Frequency 38.85MHz (Upper)2nd IF Frequency 450kH

32、z (Lower)Transmission method VCO direct oscillation amplificationModulation Variable reactance phase modulationTable 1 Basic configurationANTSWSPLPFVCOBPF/APCMPUIC8PLLIF AMP,DETTriplerx 3TCXOBPFL41,L40,L38BPFL32,L35MIXERQ161st Local OSC(PLL)RF AMPQ17ANTMCFXF1IF AMPQ24FM ICIC3Q232nd Local OSCX1AF AMP

33、IC65R5RD20D21LV6Tuning voltageD1838.85MHz12.8MHzD19A 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. First MixerThe received signal passing through the band-pass filter(L32, L35) is mi

34、xed with the first local signal generated by theVCO by the first mixer (Q16) to produce a first IF signal (38.85MHz) (Upper 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 amplifie

35、dby 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 respons

36、e 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 6.5kH

37、z)55dB or moreGuaranteed attenuation (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-K2AT/K2E/K2ET7CIRCUIT DESCRIPTION IF CircuitThe first IF signal (38.85 MHz) amplified by the IF

38、 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 c

39、omponents.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

40、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

41、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

42、 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

43、 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 t

44、he 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 ampl

45、ified 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-K2AT/K2E/K2ET8CIRCUIT DESCRIPTIONT

46、ransmitter 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 filte

47、r 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