Drake_TR-6_review_1970.pdf
CQReviews: TheDrakeTR-6 Six-MeterTransceiver BYWILFREDM.SCHERER,W2AEF THI!DrakeTR-6 is a sophisticated 6-meter transceiver similarin many respectstothe popular10-80 meterDrakeTR-4.Complete coverageofthe 50mcband is available plus additionalcoverage below the band such as may be desired forMARSwork. Operation may be had with s.s.b., a.m., c.w, orRTTY (AFSKorRFSK). Thetransmitter power runsupto300watts p.e.p. input on s.s.b. anda.m., 260 watts on c.w, and RTTY. Amongthehostofother features are: linearpermeability-tunedv.f.o. withhigh frequency stability; frequency calibration in I kc steps; f.e.t, front-end forthe receiver: flata.g.c. system with fast-attack and fast- and slow-release times; 4 filterpositions-one eachfor u.s.b., l.s.b., a.m. and c.w:;product and envelope detectors; manual r.f. and a.f. gain controls; built-in 100 kc crystal calibra- tor; amplified a.l.c.; dual meters forS-units, a.l.c. level, p.a. platecurrent and r.I. output; built-inmodulatorforcontrolled-carrier screen-gridmodulationofp.a. fora.m.; automatic carrierinsertion for a.m.; block- grid c.w. keying with waveshaping; sidetone oscillatorforc.w,monitoring; transmitter- frequency offset forc.w.; p.t.t,orbuilt-in v.o.x.operation for phone;v.o.x.-typesemi break-infor c.w.; RTTYoperation with Technical Director,CQ. The DrakeTR-6SixMeter Transceiver. S6COFebruary,1970 AFSK plus additional jack for permitting RFSKofv.I.o.;provisions for operating 2- meter transverter accessorieswithfront-panel switching furnished. A true noise blanker also is included in the unit. Thetransceiver is powered by anexternal supplyofwhich therearefive different models for use with 115/230v.a.c., 50-400 c.p.s., 12 v.d.c. or 24 v.d.c. TheTR-6 with just about everything in it but the kitchen sink is thus a very flexible job capableofproviding about every typeof operation, whether at a fixed, portable or mobile location, without requiring a lot of outboard accessories.Itis ideal forthe 6- meterenthusiastwho has many friends still operating on a.m., and yet is one thatallows newand more reliablecontacts to be made usings.s.b.or c.w. TechnicalDelails Referring to the block diagram atfig. I, double conversion is used in the TR-6. On receive the first conversion is made to a 13.9- 14.5 mc i.f. and the second is made to a 9mc i.f. On transmit, the process is in reverse.The carrier is generated at 9mcwith the first conversion made to 13.9-14.5mcand the second to the r.f.-output frequencies. The 1st receiver-conversion and the 2nd transmitter-conversion are made by hetero- dyning with 8 different36-39.5 mc crystal- controlled frequencies spaced 500 kc apart. The 2ndreceiver-conversion and the1st transmitter-conversion aremadebyhetero- dyning with a 4.9-5.5 mc v.f.o. The50rnc band is thus covered in 8 segmentsof600 kc, each with the same tuningrateand an over- lapof100 kc between segments (the TR-6 is supplied withcrystals for 49.9-51.0 mc only- crystals forothersegmentsareoptional). Forexample: on receive the 1st conversion to a13.9-14.5 mci.f.is obtained using a 36 mc heterodyning crystal forthe 49.9-50.5 mc Seepage110for NewReader Service r 12AIl7Ar 12A)(1A AG.C. 0 1 -2339 AGe . ., - A.,Del./Amp .,.- .1- 1.- 0u011FLT. ) 0 ) V, 9 VV v. vV T1588 .Pf10268166816IZ8AA12Ao/6 101 -, IZAV6lT16Glt6, A , ,. A.,. dj 1-. f- ,. f!. C, al - e- 1.f. A. Sod. -/ Fla A., 0_ .,.F A.A ., OtT, _OK A ., M V, V ,. 6816 0 , . O. , WA. . 00 2N36632N,94 _0.<. 0 1 -TlS34 AnI, Vao lgp Ant. Cal. 00< 10- )(la l vt.c Or2388 8f.o. R,cl. 8G Suff.Ole, , t:QD Ie-S.<.,.,. 1.10 ,. (V.V.V, V o1114V. 0 V,. 13J6 J B6i7r61(66J16AU612BA6 141141 I.-61714148 IAzI2V7 Dr,. ,., C. lolIlmtr.8.1Voo. Ft,loJ .A .,. j f ,I - 1.F - .A .,Reet COII,I . A ., f , , 9., .,1/01. c. L_ll!_.J .,.r. .,c. Inpt A.A.Le. . ,. 11. 1. _ .L.C. hI,e. .c. 1P .oo Det.l Amp.Amp. V. 0/1 , Fig.I- Blockdiagramfor the DrakeTR-6Transceiver. Thefilteris common to both receiver andtransmitter. Seetext fordetails. Theblankeris insertedatpoints marked X. segment (49.9-36mce13.9meand50.5- 36mc = 14.5me).Similarly a 36.5mccrystal is usedfor50.4-51.0 me (50.4- 36.5 mce 13.9 mc and51.0-36.5mc=14.5me),and so on for the other segments.The2nd con- version to a 9mci.f,is the 1sti.f.minusthe v.I.o. frequency(13.9- 4.9mc=9 mc and 14.5-5.5 mc=9 mc). Ontransmitthemixing frequencies are additive,sowe have9+4.9mce13.9mc and 9 + 5.5me= 14.5 mc forthe 1st i.f.Then, 13.9+36mc=49.9mcand14.5+36mcee 50.5me, etc.,fortheoutput frequencies. Circuitry TheTR-6 is a hybrid affair using 19 vac- uumtubes, 15transistors and 14 diodes. Ofspecial interest in the receiver section is the50mcfront-end converter whichem- ploys 3 Le.t.stoprovide excellent perfor- mance. As shownatfig.2, two TIS88 f.e.t.ts areused forthe r.f. stage in a cascade type circuit. The mixeris anMPF105 f.e.t, with theheterodyning-oscillatorsignal injectedat the sourcethroughabufferstageusing a2N- 3663 bipolartransistoras anemitterfollower. Twotrapsattheconverterinputminimize spurious responses fromTVstations. Aproblem involved withf.e.t.tsisthatof obtaining good a.g.c, performance.Thisis accomplished in theTR-6 using a vacuum- tubea.g.c,detector/ amplifier plus atwo-stage d.c. amplifier using bipolar transistors.The a.g.c. setup also is shownatfig. 2. The13.9-14.5 mci.f,fromtheconverter mixergoesthrough a 13.9-14.5mcdouble- tuned bandpass-coupling circuit tothegrid ofa 6BZ6 mixerwhere the v.f.o. signals are injectedatthe tube cathode. Upper-or lower-sidebandoperationis se- lected by switching in different 2.4 kc band- passcrystal-latticefilters after this mixer. Twoadditional filters also maybe switched in. One has a bandpassof300 C.p.s. forc.w. the other a 5 kc bandpass fora.m. Only the u.s.b. filter is supplied withthetransceiver. The others are optional accessories. Two9 mcLf.stagesareemployed.The productdetectoris a 6GX6which also func- tions as acrystal-controlledb.f.o,Thea.f, outputfrom theproduct detectoris high enoughtobefed directly to thea.f-output stage without the need foran additional a.f. amplifier. Onlyone9mccrystal is neededforthe b.f.o., inasmuch as sidebandsarechanged by switching filters.Thev.f.o., therefore, does not have toberetuned in either case. A.m. detectionis obtained withtheduo- Seepage110forNewReader ServiceFebruary, 1970CO57 He!.esc.Buffer a AC33I<A lilA . hlond2nd 12AX1 If.Amp 2N3394 12K 4.1I< I D O +15 v I 5 2N412 ( Iput 2.2I< O. 6. M .00 G801t Myers. Florida 33901 NEEDCRYSTALS? 94COFebruary,1970Seepage 110forNewReaderService
