Yaesu_FL-7000_review_CQ_1991.pdf

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1、CQREVIEWS: The Yaesu FL-7000 Solid-StateHF Automatic Linear Amplifier BY JOHN J. SCHULTZ, W4FA TheFL-7000s frontpanelconsistsonlyofvariousfieldsofpushbuttoncontrols,LEOs, andtwoanalog meters.Iftheamplifier isfUllyset up for automaticoperation, only the power on/offswitch and the operate/standbyswitc

2、h have tobe used. Remembertheold FL7000linear am- plifier? TheoldFL-7000? Probably not too many readers will really remember the FL7QOQamplifierwhichYaesuintro- ducedinthelate 19805. Atthelimeofits introductionitprobablywasbothahead ofitstimetechnicallyandconsideredtoo pricey.However,timessurelychan

3、ge. anditisfortunatethatYaesucontinuesto produce the FL7000 at what is now a very competitiveprice. The FL-7000 seemstohavebeenrediscoveredboth byamateursand dealers. The FL-7000 is a solid-stale,HF,no- tune linearamplifierthatruns 1200watts inputwithless than 100 watts of drive. Several solid-state

4、amplifierscurrently availablecandothe same. Sowhatis specialabouttheFL-7000? Iguessthe one-wordanswerwouldbepackaqinq. The FL-7000incorporates in one desk- topenclosurenotonlya linearamplifier, butalsoa110/220voltpowersupply, a completelyautomaticantennatuner, SWA andpoweroutputmonitoring,and remote

5、antennaselectionswitching (using an option). If you usetheFL-7000 togetherwithamoderntransceiverpro- viding a nominal 100wattsoutput, you canachieveacompletelyno-tunesta- tionoperatingataverycompetitive powerlevel in averycompactoverall configuration. Theoperatingease andfrequencyagil- ityofsuchaset

6、upistremendouscom- paredtoasetupinvolvinganamplifier andanantennatunerrequiringmanual tuningadjustments.Ofcourse,there are sometrade-offs. Themanuallytunedam- plifierftunercombinationcanprovide morepoweroutputperdollarifyoude- mandamaximumlegal poweroutputset- up, especially formodesrequiring long k

7、ey-down periods. Itdependsonwhat youwantforanHFoperatingsetup. I wouldsuggestacarefullook atthe FL-7000 if youarecontenttorun a desk- topCW/SSBstationatthe1.2kWinput levelwithprettymuch theultimatein operatingconvenienceandwitha minimumofstationsetupproblems. pecificalions Theoverallspecificationsof

8、the FL-7000 areshownin Table I.Theamplifiercovers allofthecurrentlyavailable HF bands, in- SPECIFICATIONS General Frequency coverage(MHz):1.8-2, 3.5-4, 7-7.5,10-10.5,14-14.5,18-18.5, 21-21.5 and 24.5-25, 28-30 except USAversion. Collector input power (final transistors): (SS8)1200WPEP,(CWIFSK)1200WD

9、C. Continuoustunpowertransmissionperiod: SSB100% for 30 min.,FUllCarrier 100% for 1min. Casesize:390W x 130H x 400 Dmm. Weight: 30kg(66 lb. Supply voltage: 10011101117/2001 2201 234 VAC(100f0). Powerconsumption: 1900VAmaximum(at 500WAF output). eluding12/10meters with a slightmodifi- cation.It can b

10、e bandswitchedbytog- gling up/downswitcheson itsfront panel,oritcanbe bandswitchedremote- ly by transceivers which providethene- Linear Amplifier Section Excitation power: lessthan 100Wfor 1200 WInput. AlCvoltagerange: Oto-9V. Spuriousradiation: lessthan - 50dB. Third-ordertntermcduranon distortion:

11、less than - 25dB. Input/Output impedance: 50ohms,un- balanced. Automatic Antenna Tuner Section Impedancematching range: 1.8-2MHz- 25 to 100 ohms, unbalanced; other amateurbands-16to 150 ohms, un- balanced. Maximum feedthroughpower: 600watts. Insertionloss: less than 0.5 dB when tunedto match. VSWRaf

12、ter matching:1:1to 1.2:1. *302GlasgowLane,Greenville, NC27858 28COMay 1991 TableI-Specifications of theYaesuFL-7ooo. Say You SawIllnCO , I r; o o o- r-0 , U.g I - l a , , , , -, , , I- I : , , -1: I , ;I :,. t I I : i t- I I o._0 ,. a I , ,. i 1 , ,J:JjHIJ-+ -. s , ,I I:. -. , I ,I,-l-_-tJ . ,.00.-.

13、KW,. 0I00l-,KWCOHNa,. lVROscreunelV .L Ot.DC.CONNO.,. Unlikeanyotherlightning p.otectlonde.leeforeon,la! t.namiulonlines, I.C.E.aModel 300aed ea.equheanop.e- detumlnedvoltagetodevelop betweeneonduetonbefore .oltageanpp.,ulonhegiDII.Unlta aeconatantd.aln,eap- ae1to.-bloeked,nonDCposl.e, andeaehrellea

14、onahea.y dl.ebargeIndnetor pa.alleled wltbaeeram lc,u-dl.eharge .,mb!ytopIe. ,-. .,-_. ._,CIooo .,.,._- - .,. .,-. ,._.- .-. .,.,., ._- .,- ._-.- .,._ . ., com. - -,_. .-.-.-, M.-. ._ -,. .-0.0., . _, .1ft.MDOSTIIAlCllII.-cATIDIlA. IIWlS.LJD.7 .uoal W. OOUS.PRas HF.VHFI-lITO 225HZ) MoonOW_.10. ORo,_

15、,NCOHNa,.,. NooR ,_,lIHC,. M OOR ,._ ,!Ie. OKOROOOAJ _. ,10. OKOR.Wll,NCONte, CATV.750t1 MOOI.RCV.oN, ._,. .THES.E.,MOllYOFTHEWIlU8.YODOCnoAKGO.O0LT CIRCLE200N READER SERVICE CARD -,._. - . .- Opw.,_. 00. .M . .,. CIRCLE58 ON READER SERVICE CARD 30COMay1991 Say You SawItIn CQ - - - cessary band-chan

16、ge information.vee- suFT747GX, FT-757GXII. FT-767GX, andFT-1000transceivers provide the necessary data, but many other trans- ceivers canbeadapted to alsodoso by suitable interface circuitry. The linear is microprocessor controlled and has a wide varietyofmemory func- tionswithftttuum-battery-backed

17、 memo- ries. Evenifband-change informationin- formation from a transceiver isnotavau- able.thelinearwill stillrememberthe tun- ersettings foreachbandandtheantenna selected for agiven band.Jlthe tuner has 10rematch a new or changed antenna load. thepoweramplifieris automatically shut down until an an

18、tenna match is achieved. The linear has very fast trans- mttrreceive turn-around time and is sutt- ablefor a SKCW, packet,andAMTOA.Its key-downperiod. however, is limited (see TableJ)unless a lowerpowerAny mode is selected.The linear is really most suited for operators who enjoy casual SSB/CW operat

19、ion with perhapsoccasional ex- cursions intokey-downmodes. The unit hasan extremely extensive ar- rayofprotectivecircuitrywhich monitors parametersin the amplifier,powersup- ply,andtuner sections. The parameters monitored range from the driving power tovarious temperaturestooutput SWR. Eight LEOs in

20、dicate various conditions. The amplifier will shutdownif various parameters are exceeded.Itwill also not shutoffifcertain temperature conditions are exceeded, even if you turnoffthe AC powerswitch! The internal fans will con- tinuetooperate until internal tempera- ture conditions have beenstabilized

21、.Im sureyou can do harm to a unit such as the FL-7000 if you are very careless, but its rangeofprotectivecircuitsisvery impressive. If you would like to do a little math using the figures shown in Table I, youll notice something interesting.The FL-7000hasa volume of less thanYocubicfoot, but weighsa

22、veryhefty661bs.Considering all that itcontains in one enclosure, it has to rate as one of themostcompact, modern linears on themarket.Again.trefer back to one ofmyopening comments about the FL-7000 being rediscovered. Circuitry A block diagramof the FL-7000, exclud- ing the power supply section. is

23、shown in fig. 1. Just a few highlightsmaybe of in- te-est.The3dBattenuator(upperleft)ac- commodates driving transceivers having more than a nominal 100 watts output (e.g. the FT-1000). The drive power is split in a hybrid transformer to drive two identicalpoweramplifiers, each of which containstwo 2

24、SC2656transistors having a collector dissipation of 300 wattseach. Therefore, a total of 1200 watts of heat- stnked powerdissipation is available. The OUtput of both power-amplifier units is combined.passedthrougharelay- switched low-pass filter unit, directive coupler, and then on to the automatic

25、antenna tuner. 4 0Cec-c I I I I I I I I I I I I I I I : PA-1l.NIT , . U RESISTOIl: V/l.Ll.SAREINn.I, 4W: CAPACITOR VALUES /IREINiF.50.v: LN-ESSOT!ERWISENOTED. T02, J02IP071 L-2;2)18IAS 103W o aO IRoe 2SC2652-0H301 002 2SC2652-0R09 TS02 eo C ,ow 2.:118 N. 0 , OJ U , ow J 0 , 0 0 , ., - , r .- 1 0 J U

26、O OJ 0 0 , w TSOI 40 C I I I I I I I I I I I 00ur II0I g0 I _J I- - I I I I I I I I I PA - I I I I o-o Fig.2-One of the twopower amplifier units in the FL7DOO.Each 2SC2652transistorasheatsinkedcandissipate upto300watts. Say YouSIWIt InCO May1991co31 Acloserlookatthe unique power-1ividerldual-power-a

27、mplifierlpowercombineras- semblygroupedaroundaverylarge, finnedneetsmcThepoweramplifiers are to the leftandrightaroundthe heatsink. Thedarkoutlinein thebottomisacooling fan. In the foregroundaresomeofthe relay-switched low-passoutputfilters. Most of the rest of the blocks shown in fig. 1 have to be

28、referenced to the CPU unit shown roughly in the middle. It pro- cesses data from the various sensory components, translates key commands, drives indicators, stores data,etc.A sophisticated solid-state linear certainly needssophisticatedcontrolcircuitry, and the FL7000 has it. Fig. 2 is a closer look

29、 at one of thetwo identical power-amplifier units. The cir- cuitry is clean and basically straightfor- ward.Th2SC2652transistorsare Toshiba units that are rated to develop 220 watts output at 28 MHz. Therefore, they certainly are not being stressed under the conditions under which they arebeingused.

30、TheoverallIMD specificationforthe FL-7000 at - 25 dB was found to be conservative, and theac- tual third-order distortion was closer to - 30 dB. That is still not on the cutting edge oftechnology, butis certainly acceptable. Thetwopower-amplifierunitsare powered by a single 47 volt, 25 ampere powers

31、upply. Thepower-supplycfr- cuitry, althoughnot shown, is rather massive.Itconsistsofasingle transformer having a dual primary and four secondary windings. Two secondary windings provide low voltages for control circuits, and the othertwowindings pro- vide voltages forthe power-amplifier stages.Here3

32、0,000mFoffilter capacitance is involved for the latter and an elaborate series regulator circuit. A partial diagramofthe automatic antenna-tuner unit is shown in fig. 3. Its not that any reader is likelytoduplicate thecircuitry, but I think most amateurs canrelate to tuners and are curious about the

33、circuitryinvolved. Automatic tuners present a particular challenge to a designer, since it is desiredtomatch a reasonable range of impedances, keep the component count low, use a circuit thatcanbe tuned rapidly,etc.Anyway, if you try to sort out the basic circuitry shown, youll see that one motor si

34、mul- taneously steps switch taps on the series inductors and chooses input capacitors. Another motor tunes the 290 pF parallel- output variable capacitor. The third mo- tor drives the 430 pF series-output vari- able capacitor. Similarcircuitryhas been used over the years in various automatic and man

35、ual tuners and is well-proven. IntheFL7000there are many other in- teresting circuits which involve control and protective circuitry. However, they are spread out overvarious PCboards, so its impossible to present asuccinct overview. like a battleship is an understatement. A look at some of the phot

36、ographs provid- ing internal views gives a hint of the quali- ty involved. The unit is densely packed, but almost everycornerseems to be rea- sonably accessible. And included are all those nice little touches, such as lacquer around the main screwheads to make suretheydontwork loose in spite of lock

37、- washers also being used. Component rat- ings appear very conservative. Its one of the finest examplesof amplifierconstrue- tlonIve seen in a long time. Just to balance those deserved com- pliments a bit, let me say the FL-7000 is the typeofamplifier you would place on an operating table and expect

38、 to have it sit thereforyears of dependable usage. Youre not going to readily tuck this am- plifier under your arm and run off for a bit of portable operation! Various shield covers were removed for the photographs, but the construction is broken down basically into compart- Construction Mechanicall

39、y,the FL-7000 is an amazing piece of equipment. To say that it is built 32COMay1991 Thebackpanelshows the cooling fan for thepowersupplyplusthe various connec- tors. Theterminalstrip in the lowermiddlesuppliesanoperating voltage for up to three external antenna relays whichcanbeswitch-selectedfrom t

40、he frontpanelofthe FL- 7000. SeparateALe-leveladjustmentsareprovidedforsseandRTTY(upper left). Say You SawItIn CO Fig.4-Schematic ofaremote antenna switching unit you might buildto mate with the FL-7000.Any12VDC relay type havingsuitable RF insulationandacoilresistanceof less thanafew hundredohmswou

41、ld be suitable(e.g.,Radio$hack275-218). 4 3 c c - a f , s . - o, ; I.-U I I ;,J I L,0 -. I I I I I I I I I I I I I CO,220 0 . C02OOp - , , , . .- , Be c , 0 , J , . , . , ? Zli I s ; Fig.3- Apartial diagramofthe automatic antenna tuner which covers 160-10meters. SAYVnnSAWItInCO May 1991CO35 - Manual

42、 The manual for the FL-7000 (circa 1986) is weltwritten.The operating instructions are quiteclear, and a multitude of inter- connection diagrams for various trans- ceivers is presented. A four-page large- size set of separate diagrams which cov- er allofthe basiccircuitryis included. The manual is n

43、ot a service manual, butitcomes close to being so. A four- page section contains some quite de- tailed alignmentprocedureswhich can beperformedin the field using only a good multimeter, adummyload, and a wattmeter. Photographs clearly show which internal adjustments are involved during alignment. Be

44、 careful, however, that attempting an adjustment on a new Once it is initially set up, operating the FL-7000 is extremely simple. Once a band ischosen, the automatictuner goes to itsmemorized position and the memor- ized antennaselection. Ifyou go backtoa band previously used, the amplifier isin- st

45、ant on. If you go to another band, the only time delay is the amount of time it takesfortheautomatictuner to reset. Themetersare always easy to read, sincetheyare back-lighted. The opera- tional-status LEOsareeasyto discern be- cause of theircolors-greenforready, yellow forwait, and red for various

46、warnings. The greenband LEOs are readily visible, but the band marking for each LED is unreadable in a semi-dark room.This isnoproblem if the FL-7000 is automaticallybandswitchedfroma transceiver. However, if the FL-7000 is manually bandswitched, the onlywayI found to readily tell the band inuse was

47、 to putvertical,whitemarkingsonthe bandLED field to separate it into three groups ofmree-c-t.e.3.5, 7 MHz; 10, 14, 18 MHz; and21,24,28MHz. Although it stillwasntpossibletoread the MHz markings, it was easy enough to see the position of the illuminated LED relative to its position in a group. The FL-

48、7000 deliv- ers a solid signal. If driven with only the necessarypowerto produce full power output, it provides almost a 10 dB power boost. Thats quite a bit, and as the ads say, youll be less than an8unit down from stations running the full legal limit. Everyone has to define the equipment needed for his own operating prefer- ences. I found the FL-7000 a delight to use along with a modern transceiver. It wassort of like years ago when I was on topof the world using a Collins KWM- 2J30L1combo. Howe