Icom IC-F6012 Service Manual

Also see for IC-F6011: Instructions

Contents

Icom IC-F6012 Service Manual Manual pdf 13 page image

5 - 35-2 TRANSMITTER CIRCUITSMIC AMPLIFIER (FRONT UNIT)Audio signal from the connected microphone is applied tothe MIC AMP (IC5), through the microphone connector (J1).The amplifi ed MIC signal is applied to the MAIN-A/-B UNIT.TX AF CIRCUITS (MAIN-A/-B UNIT)The MIC signal from the FRONT UNIT is passed throughthe D/A converter (as a MIC gain controller; IC18) for leveladjustment, and applied to the limiter AMP which is alsorolled to the pre-emphasis circuit (IC16).• TX AF CIRCUITSMIC MUTE SWITCH (MAIN-A/-B UNIT)The pre-emphasized MIC signal is passed through the MICmute SW (IC14).While receiving or transmitting DTMF, 2/5 tone and BIISsignals, the MIC mute SW (IC14) cuts the MIC line off, andis controlled by “MMUT” signal from the expander (IC17).SPLATTER FILTER (MAIN-A/-B UNIT)The MIC signal from the MIC mute SW (IC14) is applied tothe splatter fi lter (IC16).The splatter filter (IC16) is also used as the AF SummingAMP for tone signal modulation (CTCSS, 2/5 TONE).MODULATION CIRCUIT (MAIN-A/-B UNIT)MIC signal from the splatter filter (IC16) is level-adjusted(=deviation adjustment) by the D/A converter (IC18), andapplied to the TX VCO (Q13, D16, D18), through themodulation mute SW (IC14) as the modulation signal.The MIC signal is also applied to the reference frequencyoscillator (X2) as the modulation signal, through D/Aconverter (IC18) and REF AMP (IC19).• MODULATION CIRCUITSCTCSS/DTCS SIGNALS ENCODING (FRONT UNIT)The CTCSS/DTCS encoding signal from the CPU (IC1)“CENC0–CENC2” is passed through the LPF (IC5) forwaveform conversion, and applied to the MAIN UNIT as tonemodulation signal.2/5 TONE, DTMF ENCODING (FRONT UNIT)Encoding signal from the CPU (IC1) named “SENC,” ispassed through the LPF (IC5), and applied to the MAINUNIT as tone modulation signal.TX AMPLIFIERS (MAIN-A/-B UNIT)The frequency-modulated signal from the TX VCO is buffer-amplified by two buffers (Q11 and Q10), and applied to theYGR AMP (Q9) as the TX signal through the LO SW (D14).The TX signal is sequentially amplified by the YGR AMP(Q9) and drive AMP (Q8). The amplified signal is appliedto the FET HPA module (IC3) through the LPF, and power-amplifi ed to obtain TX output power level.The power-amplified TX signal is passed through theantenna SW (D3) and LPF as a harmonic filter, and then fedto the antenna.APC CIRCUIT (MAIN-A/-B UNIT)A portion of TX signal rectified by D1, D11 and D12 onthe TX line to detect TX power level. The rectified voltageis applied to the APC AMP (IC2), and the APC AMPcontrols the gain of drive AMP (Q8) and HPA module (IC3)automatically by comparing the rectified voltage and thepower setting voltage "T1."• TX AMPLIFIERS APC CIRCUITREFOSCX2CR-794TX/RXSWD14,D15Q13,D16,31FILLOOPPLLICIC4MB15A02FMMODD18BUFFQ10BUFFQ11IC19AMPREFTX VCOBAL15.3 MHzFrom the D/A converter From the MIC line SWTo TX AMPsLVLPFLPF LP FLP F PWRDETD1,D11,D12MUTESWD28ANTSWD3PWRAMPICRX circuits3APCAMPIC2DRIVEAMYGRAMP PQ8Q9T1 TMUTFrom TX VCOSplat.IC16AMPIC16AMPIC5MIClineSWMICD/AIC14CD4066IC18MICROPHONECONNECTORJ1FRONT UNITMICBALTo the Referencefrequency oscillatorMODIMCOTMCGOTONECDTSMODVRAF TX VCOSPIN