Kenwood TH-K4AT Service Manual

Also see for TH-K4AT: Instruction manual Instruction manual Service manual

TH-K4AT/K4E1598 DCDET I DC IN detection interrupt input (↓)L:DC IN connected99 RXLED O Busy LED output H:ON100 BSFT O Beat shift swiching output H:ON101 PLLEN O Serial enable output to PLL IC102 PLLLD I Lock detection input from PLL IC H: Lock103 KIN0 I Key matrix input 0104 KIN1 I Key matrix input 1105 KIN2 I Key matrix input 2106 KIN3 I Key matrix input 3107 KIN4 I Key matrix input 4108 TYPE I Market code bit input109 VUKEY I Detection of VHF or UHF, 4 key or 16 key110 MICM O Microphone mute switch H:Mute111 NOAA I Not used112 5R O RX power supply switch L:ON113 SHIFT O VCO shift switch L:RX, H:TX114 5T O TX power supply switch L:ON115 KOUT0 O Key matrix output 0116 KOUT1 O Key matrix output 1117 KOUT2 O Key matrix output 2118 KOUT3 O Key matrix output 3119 VSS - GND120 BTDET O Battery detection switch L:ONSEMICONDUCTOR DATA / COMPONENTS DESCRIPTIONPin Pin I/O FunctionNo. NameIC1 PLL ICIC2 APC differentialamplifierIC3 FM ICIC4 11.5V AVRIC5 HPF Active filterIC6 AF amplifierIC8 MPUIC9 5.0V AVRIC10 4.4V voltage MPU INT voltage detectiondetectionIC11 3.3V voltage MPU Reset voltage detectiondetectionIC12 5.0V AVRIC15 EE PROMIC16 MIC amplifier Limiter, splatter filterIC17 CTCSS/DCS Active filterfilterQ1 VCOQ2 RF amplifierQ3 VCO shift On TXcontrol switchQ4 Ripple filterQ5,6,9 RF amplifierQ10,11 Drive amplifierQ12 Power amplifierQ13 APC circuit On TXoperation switchQ14 APC output On TXswitchQ15 Q10 operation On TXswitchQ16 1st mixerQ17 RX 1st amplifierQ20 Audio mute Audio mute when offswitchQ21 Audio filter Active filterQ22 Wide/narrow On when wide is selectedswitchingQ23 Tripler 2nd localQ24 IF amplifier 1st IF 38.85MHzQ27 Wide/narrow On when wide is selectedswitchingQ29 MIC mute Mutes when ONswitchQ30 VOX detectionamplifierQ31 Q56 operation Off when the speaker outputs audioswitchQ33 Charge switchRef. No. Use/Function Operation/Condition/CompatibilityTX-RX UNIT (X57-675X-XX)COMPONENTS DESCRIPTION