TH-F6A/F7E11CIRCUIT DESCRIPTION4-1. A band receptionIC6 functions as A band reception PLL. This PLL IC controlsthe VCO produced by Q34. VCOs are changed over byswitching the power provided to each VCO by Q35 throughcontrol line "DAVCOS" from the CPU. VCO power passesthrough a ripple filter consisting of Q31 and C235.RIPPLE FILTERQ312SC4617(S)Q38MA2S111Q35HNIJ02FUSWQ70 2SJ243Q69 DTC144EESHIFT SWQ34MT6C03AED35,371SV305D36,34MA25304D40HVC131VCOIC6LMX2326TMXPLLQ372SC5108(Y)AMPQ402SC5009AMPQ412SC5009AMPQ45MT6C04AEMIXLPFTUNED28,106HVC375BA4-2. B band reception and transmissionIC2 functions as B band reception PLL. This PLL IC controlsthe VCO produced by Q9. VCOs are changed over by switchingthe power supplied to each VCO by Q10 through control line"DBSS" from the CPU. VCO power passes through a ripplefilter consisting of Q7 and C52. Each VCO output is amplifiedby a common amplifier (Q13).4-2-1. 0.1MHz-267MHz reception, VHF (220MHz only>) band transmissionThe VCO oscillator frequency is UHF. The signal outputfrom Q13 goes to the prescaler IC (IC3) and is divided into 1/8(0.1MHz-23MHz), 1/4 (23MHz-104MHz), and 1/2 (104MHz-267MHz). Division is controlled by using control signals "SW1(Q15)" and "SW2 (Q15)" from the CPU. The division output isamplified by an amplifier (Q19), and the signal goes to themixer (Q28) during reception and to the drive duringtransmission. The PLL IC FIN input is generated by extractingthe output from Q13 and amplifying it with an amplifier (Q11).4-2-2. 267MHz-707MHz reception, UHF transmissionThe Q13 output goes to the mixer during reception and tothe drive during transmission. The PLL IC FIN input isgenerated by extracting the output from Q13 and amplifyingit with an amplifier (Q11).4-2-3. 707MHz-1.3GHz receptionOutput signal from Q13 is amplified by an aplifier(Q11), thenthe signal is multiplied by 2 by a multiplier (Q12). The signalis then amplified with three amplifiers (Q21), and goes to themixer (Q28) during reception and to the drive (Q71) duringtransmission. The FIN input of the PLL IC (IC2) is input bytaking the output from Q11.Q132SC5108(Y)AMPQ122SC5009AMPQ212SC5009Q93MT6C03AEAMPAMPQ192SC5009AMPQ712SC4226(R24)Q722SC5192AMP AMPQ28MT6C03AELoMIXQ542SK2973Q562SK2973DRIVE AMP DRIVE AMPQ552SK3476RF POWER AMPSWD99HSC277D100HSC277D101HSC277DEVIDERIC3UPB1509GVSWD102HSC277LPFHPF HPFSWD53D54HVC131SWD49 D85D50 D86D51D52HVC131VHFUHFLPFLPFBPFANTQ2MT6C03AED18 HVC131D11,12HVC3758D21 HVC131D10,16HVC3758VCOBEach VCO output is amplified by a common amplifier Q37.In VHF/UHF band reception, the signal passes through a low-pass filter, is amplified by Q40, then by a common localamplifier (Q41), and goes to a mixer. This low-pass filter usesa varicap (D28, D106) to shift cut-off frequency. The FIN inputto the PLL IC is taken from the Q40 output.Fig.15Fig.16
