Icom IC-F1000 Service Manual

Also see for IC-F1000 series: Instructions Operating guide Instructions Instructions Instructions

Contents

Icom IC-F1000 Service Manual Manual pdf 9 page image

4-1SECTION 4. CIRCUIT DESCRIPTION• RF CIRCUITS• 1ST IF CIRCUITS• 2ND IF CIRCUITSLPFANTSWD19,D27RFAMPQ39BPFD18 D25BPFD31BPFD29BPFFrom the TX circuits1st IF circuitsANTT1T2TX/RXSWD16,D17Q37BPFXTALFI1IFAMPQ33BUFFQ31BUFFQ30HPF** LPF*RX VCOTo the TX circuitsFrom the RF circuitsTo the 2nd IF&demodulator circuits 46.35MHz1st IF mixerPLLICIC15BPFX3TCXOD/AconverterIF IC From the 1st IFcircuitsTo the RX AF circuitsIC1615.3MHz45.9MHzDISCSQINIC10NOIS• RX AF CIRCUITSInternal speakerExternal speakerFrom the demodulatocircuitsAFAMPIC1J2SP1AFAMPJ312LPFIC11VOL1R133AMPLPFAMPIC10AFONAFOEMPHEXP HPFIC44-1 RECEIVE CIRCUITSRF CIRCUITThe RX signal from the antenna is passed through the LPF(L29 to L31, C333, C347 to C350, C352 and C403) andantenna SW (D19 and D27) then filtered by the 2-stagedtuned BPF (D25 and D31) to eliminate unwanted out-of-Band signal. The filtered RX signal is amplified by the RFAMP (Q39), and filtered by another 2-staged tuned BPF(D18, D29, D36 to D38) to obtain a good image response,and then applied to the 1st IF circuit.The tuned BPFs are tuned to the RX frequency by apply-ing adequate tuning voltages (“T1” and “T2”) to the variablecapacitors.1ST IF CIRCUITThe RX signal from the RF circuits is applied to the 1st IFmixer (Q37) and mixed with the 1st LO signal from the RXVCO, resulting in the 46.35 MHz 1st IF signal. The 1st IFsignal is filtered by the crystal filter (FI1), amplified by the1st IF AMP (Q33), and then applied to the 2nd IF circuit.2ND IF CIRCUIT AND DEMODULATORThe signal from the 1st IF circuits is applied to the IFdemodulator IC (IC16) which contains the 2nd IF mixer, 2ndIF AMP, FM detector, and so on.The 1st IF signal is applied to the 2nd IF mixer and mixedwith the 2nd LO signal resulting in the 450 kHz 2nd IF sig-nal.The 2nd LO signal is generated by tripling the 15.3 MHzreference frequency signal oscillated by the reference fre-quency oscillator (X3).The converted 2nd IF signal is amplified by the 2nd IF AMP,and then demodulated by the detector circuit.The demodulated AF signal is applied to the RX AF circuit.RX AF CIRCUITSThe demodulated AF signal from the IF demodulator IC(IC16, pin 14) is applied to the baseband IC (IC4).The processed AF signal is passed through the LPF (IC11),which attenuates frequencies 3 kHz and above, and adjust-ed in level by the D/A converter (IC10). The level-adjustedAF signal is then applied to the AF power AMP (IC1).The amplified AF signal is applied to the internal or externalspeaker.*:For [EUR] and [UK] versions.**:For except [EUR] and [UK] versions.