Kenwood TS-950S Service Manual

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TS-950S/SDCIRCUIT DESCRIPTION¢ SLOPE-TUNE, IF VBTFigure 4 shows the TS-950 SLOPE-TUNE and IFVBT receiver configuration.The operating principle of SSB-SLOPE-TUNE circuitis explained first. When fML1, fML3, and fML4 in Figure5 are at their normal frequencies, the synthesized band-width is indicated by A. When the frequencies offML3 and fML4 are lowered by an amount equal to Af1,only the third IF filter (455-kHz band) shifts to positionB. (The circuit is designed so that the PLL data lowersthe frequencies of fML3 and fML4 equal to the valuedetermined by Aft.) The synthesized bandwidth is theoverlapping portion of A and B. When the frequenciesof fML1 and fML3 are lowered by an amount equal toAf2, only the the second IF filter (8.83-MHz band} shiftsto position C. The synthesized bandwidth is the over-lapping portion of B and C. The SSB-SLOPE-TUNEallows these operations to be conducted independ-ently, using two separate controls.The frequencies are generated by the PLL circuitand controlled by the microprocessor. The amount ofchange in Afi and Afz, is digitally tracked, allowing onlythe bandwidth to narrow without changing the centerfrequency of the composite passband.We will now cover the operating principle of theSSB-SLOPE-TUNE circuits. These circuits are designedso the relationship between the frequency changes ofPLL data are such that Af2 = Afi. The synthesizedpassband widths of the third IF filter (fi-3) and thesecond IF filter (fiF2) can thus be varied by a singlecontrol.Bra iF455KHz oiscRt1 IN10K~30MHzMAIN,RxeM A 4X)ar1ML2 64,22MH2PLL(veo a)1MLY73.06 ~ 103.05Muz(firI~ata)CMU 1-412)Mit At2 PLL DATAcru cruour PUTLOMng1Cw! 9,92MH2)PLL4.A )iveos)(PMLa—at 1)tML 4Fig. 4-b Band variable frequency configurationIF-VBTAf2‘4alHi-CutLow-Cut}-—++}=-4aeehSLOPE-KeSLOPE-1‘1Ar~\ReceivingTUNE|Va)TUNE!‘signal(CW);!\Receiving 8H!Interfering \signal(SSB)‘7Interferingsigna!(SSB)1\interfering1nal(SSB)!1signal(cw),fy39!InterferingcV3N'\signal(CW)\!WUNFig. 4-cIFVBTFig.4-dSSB-SLOPE-TUNEFig.5 15