Icom IC-R6 Service Manual

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Icom IC-R6 Service Manual Manual pdf 9 page image

4 - 1• 15–29.995 MHzThe RX signal from the antenna connector (CHASSIS; J1)is applied to the RF AMP (Q505) through the band SWs(D63, D64 and D73), LPF and the HPF.The amplified signal is passed through the band SWs (D71and D72), and then applied to another RF AMP (IC18).• 30–117.995 MHz and 175–329.995 MHzThe RX signal from the antenna connector (CHASSIS; J1) isapplied to the RF AMP (Q36) through the band SW (D13) andthe BPF. The amplified signal is passed through the band SWs(D34 and D71), and then applied to another RF AMP (IC18).• 118–174.995 MHzThe RX signal from the antenna connector (CHASSIS; J1)is applied to the RF AMP (Q14) through the band SWs (D74and D75) and BPF. The amplified signal is passed throughthe tuned BPF (D1 and D2) and band SWs (D25 and D71)and then applied to another RF AMP (IC18).• 330–469.995 MHzThe RX signal from the antenna connector (CHASSIS; J1)is applied to the RF AMP (Q35) through the band SWs(D3 and D75) and the BPF. The amplified signal is passedthrough the tuned BPF (D4 and D5) and band SWs (D29and D71), and then applied to another RF AMP (IC18 ).• 470–832.995 MHzThe RX signal from the antenna connector (CHASSIS; J1)is applied to the RF AMP (Q24) through the band SWs (D11and D75) and BPF. The amplified signal is passed throughthe band SWs (D32 and D71), and then applied to anotherRF AMP (IC18).• 833–1309.995 MHzThe RX signal from the antenna connector (CHASSIS; J1)is applied to the RF AMP (Q26) through the band SW (D13)and BPF. The amplified signal is passed through the bandSW (D36), and then applied to another RF AMP (IC18).The signal from the RF AMP (IC18) is applied to the 1st IFcircuits.4-1 RECEIVER CIRCUITS (RF UNIT)EARPHONE ANTENNAWhen using the connected earphone as an antenna, RXsignal from the earphone is applied to the RF circuits (except0.10–1.895 MHz band), through the earphone antenna SW(D101 and D109).ATTENUATOR CIRCUITWhen the attenuator is activated, the PIN diode (D68)is forward-biased and a 10 dB (approx.) attenuator iscomposed.The switching of D68 is carried out by Q521 with the controlsignal “ATT.”RF CIRCUITSThe RX signal from the antenna is applied to appropriateRF circuits, according to the RX frequency.• 0.10–1.895 MHzWhen using an external antenna;The RX signal from the antenna connector (CHASSIS; J1)is applied to the RF AMP (Q505) through the band SWs(D66, D67 and D73) and LPFs.When using the internal bar antenna;The RX signal from the internal bar antenna (CHASSIS;EP2) is applied to the RF AMP (Q505) through the ANT SW(D76).The amplified signal is passed through the band SWs (D71and D72), and then applied to another RF AMP (IC18).• 1.9–14.995 MHzThe RX signal from the antenna connector (CHASSIS; J1)is applied to the RF AMP (Q505) through the band SWs(D65, D70 and D73), LPF and the BPF.The amplified signal is passed through the band SWs (D71and D72), and then applied to another RF AMP (IC18).• RF CIRCUITSSECTION 4. CIRCUIT DESCRIPTIONRFAMPBPFBPFBPFTUNEDBPFTUNEDBPFJ1(CHASSIS)BPFBPFATTANTSWLPFLPFBPFHPFRFAM PRFAM PRFAM PRFAM PRFAM PRFAM PBANDSWBANDSWBANDSWBARANTENNABANDSWBANDSWBANDSWATTRF UNITD13,D31,D73,D75D63,D65,D66Q510,D76D64,D67,D70Q505,Q527D3,D11,D74Q14 D1,D2Q35 D4,D5Q24D25,D29,D32,D34,D72Q36Q26 D36,D71 IC18To the 1st IF circuits0.10-29.995 MHz0.10-1.895 MHz0.10-1.895 MHz1.9-14.995 MHz15-29.995 MHz118-174.995 MHz330-469.995 MHz470-832.995 MHz30-117.995 MHz175-329.995 MHz833-1309.995 MHzQ521D68EARPHONEANT SW Q514,D101,D109ANT CONNECTOR EARPHONES ANTENNAJ2EXT SP