Kenwood TS-950S Service Manual

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TS-9505/SD18CIRCUIT DESCRIPTIONTransmitter Circuit ConfigurationThe transmitter system configuration is shown inFigure 7. The transmitter system operates as a tripleconversion system in SSB, CW, and AM modes, andas a double conversion system in FM mode.The audio signal from the microphone enters switchunit (A) (D/10) and switch unit {A} (H/10) from themicrophone connector board. The signal is amplifiedby the MIC AMP module and passes through bufferamplifier Q17 (2$C2712) and splits into the SSB/AMMIC system, and the FM, VOX system. !nputs fromthe rear panel enter from the PHONE IN and ACC2lines on the IF unit, are amplified by Q42 (2SC2712),and then matched with the input of Q17 on the switchunit {A} (H/10).The SSB and AM MIC system of switch unit (A) (H/10) is routed to the MIC GAIN VR and the PROC IN VRon the same board. When the speech processor isturned on, with switch $59 of switch unit (A) (G/10),PROC IN is selected. When the speech processor isturned off, the MIC GAIN output is selected.The FM and VOX signals of switch unit (A) (H/10)are switched to the FM and VOX systems by switchunit (A) (E/10). The FM signal enters the FM MIC AMPcircuit of the AF unit, and the VOX signal enters theVOX circuit of the AF unit via the VOX GAIN VR ofswitch unit (A) (E/10).The SSB and AM MIC signals enter the signal unitand are amplified by IC9 (TA7140P) to a level sufficientfor modulation, and are then modulated by ring modu-lator D41 (ND487R1-3R) to produce a 455-kHz DSBsignal. In the AM and CW modes, D41 Is used as acarrier attenuator by applying DC bias to D41. Thecarrier level is adjusted by changing the level of VR11CAR LEVEL VR on switch unit (A) (J/10). In the FMmode, the carrier level is set by VR6 (FMC) on thesigna! unit.TheDSBsignalisamplifiedbyQ12(3SK131)onthesignalunit,andispassedthrough ceramicfilterCF101.Theunwantedsidebandiseliminatedinordertogen-eratea455-kHzSSBsignal.TheFMandFSKsignalsalsopassthroughCF101.TheCWandAMsignalspassthroughCF1.The455-kHzsigna!passesthroughbuffer amplifiersQ26andQ25(2SC2712x2},andareroutedfromthesignalunit.jUSwiad UNIT 7 lar UNIT 7 i SIGNAL UNIT| ! |i F \e251 ont ba, mr| ascarid 2geariarr | {fan \eugrasgr SRST sp 5nr2We | 1p MAyrese F petMa ame auFF | \ ave o ‘pao ! . reeee i a ee ee :: | OFF 388 - usa aszonur | ——art | : ia U5e a86.5 erteucne = : ze i 7 «| Bae a5eeeN a 4a = ‘ Ww asa. if rsane | [eu }— 535 2 geo : ee| : oar zo | ; —————||| aF(TT runt || me |lo ON F5KLl aes 05c21zaH?2234H::SIGNALUNITIieunitaireUNITi5Toe34036.37aurph}thAesae[eels/7mayieee:MnixPo.zeswer“zonZRH?Foero33isse30!ascareziy)tertoze—agmictimyasseza=exneiHITFDaceis{we}foeieHierLI8|worflen/aeee=4¥SKHT=isa.iM=-||osearareyetSowspbeye AaaSaEBEaunt[aeeeune:|mieMe=+ieLdawesc27i2iry®Pros1"Trane|pesceronecssosue38O85]ISeuses|i:Meghereaeen‘iets:|AFUNIT1CrinatunitTVfricrerunit7farontaN||!VW220.21ozebisaastveniel|as |assem?LersmneSsKIStIMI ascamavconyy|29009ascai33e2MRFAZOMe|eeu||[7oFNeBeL-tde]caifeDRIVErinaLebelvar+|veraTmis1|Vl16-29,7Athhysage|14Bre1|Iiony contiivstoRyp14.5029.7MErarrinoe.* .LeatheJFig. 7Transmittercircuitconfiguration