SGC_SG-2020_review_1999.pdf

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1、-111- TheSGCSG-2020 SSB/CWHFTransceiver BY DAVE INGRAM, K4TWJ ThenewSGC SG-2020 HF transceiverissmall, rugged,andbuilt for action with an impressivearrayofbig-time features which include20memories. built-in keyer, digi- talSCAFfilters, SWR monitor,SSB speech compressor.andmore. F eeling a bit bored

2、with uneventful daily routines? Want to experience newamateurradio thrills andexcite- ment?Gearupwithanewrig,tutttrebands inhighstyle, and start living the good life! Dumb advice?Notat all. It works great and turnsgoodresults every time. Realty! But new transceivers with a respectable number offancy

3、features cost a bundle. right? Notnecessarily.All-outdeluxeunits are expensive, true,butlookbeyond that trentline ofgear and you will discover some realtreats at surprisinglyaffordable prices. Yes, and generally speaking, these less-expensive rigs are capable of working almost anything the super rig

4、s can work. One good example of this lact is the subjectofthis COrel/iew:SGCs newSG- 2020SSB/CW transceiver. Thisisa high- calibre rig with a proven, solid back- ground.Itmakesaveryniceunitforhome. mobile,orportableoperation,anditsports a fair and squareprice tag toboot.Sound appealing? Read on! The

5、 BasicFacls SGCs new SG-2020checks inwith mea- surementsof2.75H)(6W)(70,aweight of4.5pounds.and ablue-graycolor case that seems impervious to rough handling or abuse.It has a well-balanced. rubber- ized tuningknob.backlit multifunction fre- quency readout. LED-type bar meier. frontflip-up foot. and

6、hefty top-mounted speaker.Recessedfront-panelLEOsindi- cate when the rig is operatingtransceive or split frequencies,whenits noiseblank- er and/or RITtson.and when it isintrans- mit mode. Combined with the meters greenandredLEOs,thisproduces acap- tivatingbrightlights andqlamcurlook during use. The

7、SG-2020 operates SSB and CW on allnine HF bands with up 1 0 20 walls outputand receives (SSB andCWonly) from 1.8 to 30.0 MHz wilh very good sen- sitivity and selectivity (additional specs of interest are listed in Table I).IIrequires 12 1014voltsDC al 4 to 5 amps for oper- ation at 20 watts output o

8、r approximately 1.5 amps for QRP operation at the 4 or 5 watt level. Receive-onlycurrentis around 04941 Scenic ViewDrive,Birmingham,AL 35210 30 CO0June1999 400 ma wilh Ihe readouts backlight switchedoff-justright for battery-pow- ered QRP field operations. Speaking of QAP. I should also men- tion Br

9、uce Franklin. KG7CA, of Index Labsand father of the now-famous QAP Plustransceiver wasakeymember ofthe SG-2020s design team. As such, it is an even more elaborate and feature-packed version of that popular unit. This is a real compliment 1 0 the SG-2020, because QRPers traditionally thrive on copyin

10、g weakOX-like signals through QRM and adverse band conditions. And since the liltte rigs power is front-paneladjustable from 1walltofulloutput,itaddressesboth traditional amateur and QRP markets very effectively. Deluxe and Special Fealures Touring the SG-2020s front panel and punching some of its r

11、ubberized buttons hints at more special features and func- ticnsin this ultra-compact transceiver thanfirst meet the eye.The little tiger has 20fully tunable memories, digital SCAF CWfilters from 2.7 kHz to 100Hz, built-in iambickeyer.passband tuning, AIT,split- frequency capability, and SWA monitor

12、- ing-aliin one box. These features are first accessed by pushbuttons. and then changedbyrotatingthemaintuningknob. Band selection,for example, involvesus- ing thaI two-step process for recalling a memory1 0the VFO. Any desired fre- quency can then be tuned in plus pro- grammed backintomemory for qu

13、ick access to a favored operating spot. Heresthespecialkicker.Youcanrecall a memorized frequency and check activ- ity,tune the band for moreactivity,punch theMEMwbutton to recheck or operate the memorized frequency, then punch MEMagain for toggling frequencies. Even a third frequencycan be includedi

14、n this toggling concept, or favorite frequen- cies can be programmedintoadjacent SayYou sawItIn CO , Optional snap-on frontandrear covers convert theSG-2020intoaself-containedsta- tion thatgoes withyouanywhereandanytime. Batteries installinrear,andmicro- phoneandkeystore in front. (Photo courtesy SG

15、C, Inc.)1 bandwidthdown10100 Hz without ring- ing. Did I mention this transceiveralso has band andmemoryscanning10helpyou find the action requiring narrow filtersand sharpoperating savvy? Indeed, the SG 2020is a lot of rig for the money, Inclusion ofSWRmeteringand an iambic keyercomplete with speed

16、display givetheSG-2020 verygoodflexibility and portability. (Why fumblewith exira pieces if yougetthembuilt into yourtranscev- er?!) Both keying andsidetone.inciden- tally, arecleanandpleasant to copy. Whethertherigworksfull or semiCW break-independs, inmyopinion, on your keyingspeed. At stowhand-ke

17、y speeds theTIRrelayswitchesbetween dots and dasheslor fullaSKaction. At higher bug or keyer speeds, itswitchesbetween let- ters orwordsfor semi QSK. T/R delay is not readily adjustable.T/Rrelay noise is betweenbarely noticeableand rather noticeable, depending onyourpersonal point of reference. Idon

18、ot find it overly objectionable, but I alsoappreciate the heartwarmingsoundsof a classic tele- graphoffice in theshack. Amateur radio life shouldbeflashy and fun, right? memoriestorqcick-cneckaccess.Overall flexibility is remarkable. Selection of narrow-band utters. keyer speed,passbandtuningadjustm

19、ents.and separate receive frequencies arehandled in a similar push related button and rotate main tuning knob manner. In each case, theSG-2020sfrequencyreadout changes10indicateyourselectionwhen accessed, and shifts back to your operat- ing frequency when the related button is released. Adjusting th

20、e passband tuning with the main knobwhilewatching the dis- play show minus or plus 1, 2, or 3may seemunusual,butafter alewminutes of use it actuallyproves very clever and con- venient.Somefunctions, incidentally, are accessedbysimultaneouslypressing two bunons-forexample,byholding in the BandWidthan

21、dREVersebuttonsto switch operatingmodes. TheSG-2020sSCAFuttersdeserve favorable mention, as theyworkgreat for cuningQRMandcan evennarrow receive I Taking It With You Ifyou travel or pursue outdoorhamming to any reasonabledegree. the SG-2020 hasone option worthy ofyourinvestiga- tion: snap-on frontan

22、drear covers with integral shoulder strap for easy carrying, Abankof 10 D cells forpowerfit in the rearcover, and the rigs included hand microphone (plusmaybe a scratch pad and small key or paddle of yourchoice) canbestored in thefront cover,Wrapa .DRlCtllOIllU IIGIII,.,L1IUF.LFI(R FILTER.IIID IIU:I

23、I /, Y ROTECtllOIll nROR,n CllnUl J,nR FIUIII -; MIXER AUDIOFilTERS AO CtIRCtUIT r-r- .IPUFIEA 1 lANKIR AMPUAER /, BFO t-oo- / veo /, t-o.o- I GAIN . /, TR.,HIr-,CONTROL PRlAlilI t-o.+o-IfNTHESllER AIIPLI/ / /,MICROPHONE .Uo- r-, l.,./0-+.- ALe lGOAol LOWPASS .,.0.,0:1.0 FILTERS 0 . O.OLI ANTENNA I

24、Fig.1-Conceptual block diagramoftheSG-2020. (See full discussion text.) sayYou Saw II In COJune1999CO31 Table1-Generaloverviewoftechnical specs for the SG-2020HFtransceiver. Example: At 14.2 MHz . 14.2 x 3+42.6 Hz. A total Irequency drift0142.6 Hz lor a temperature change 0110C. II the ambient tempe

25、rature changes trcm 20 to 30C, there could be a drift0142.6 Hz. On TheAir So how does the SG-2020 rate in actual operationandperformance,youask?Ex- ceeds expectations is, in my opinion, a good quick reply. All of therigs features except its non-adjustable TfR delay are terrific. The receiver section

26、 is particular- ly good, not just in sensitivity and selec- tivity, but also in high intermod immunity. Interference from shortwave superstation WEWN has caused wall to wall birdies on many transceivers checked at my QTH, but the SG-2020 passed this acid test by copying signals right down to a bands

27、 noise level. The adjustable-width audio filters arealso dandy forminimizing on-frequency QRM-assumingyou re- member to reduce RF gain to avoid front- endbuckshotttnqfrom signals squeez- ing through the IFs crystal filter. This is not an unusual idiosyncrasy, however.It is common with any rig using

28、(internal or add-on) audio-levelDSP. Thanks to conservatively rated RF amplifierstagesandhighly effective speechcompression,theSG-2020s transmitter section pumps out a most commendable signal on both CW and SSB. Is 20 watts enough power forwork- ing out in areliable manner? You bet it is!At theworst

29、,itisonly two S-units below a 100 watt signal, and the AGC circuit in modern transceivers compensates for that variation so you cannot hear thedit- ference. The only way you will notice the change is by watching an S-meter. Hon- est! Check my words of wisdom on your own rig and see for yourself! Hig

30、h-power- gle, but actually consists of four broad- band stages complete with a pair of 40- watt rated transistors in its output.From there,the signal passes through a bands related filter and to the output. Now lets quickly discuss a couple of fine points. Both first and second mixer stages use diod

31、ering-type circuits rather than active ICS (like an NE 602, for example). This is a prime reason why the receiver exhibits wide dynamic rangeand alownoise floor. Also, many birdies are eliminated bythe use of up conversion and a 60 MHz IF (incoming signal minus local oscillator equals IF). AGC volta

32、ge is derived at the SCAFfilteroutputand fedbacktothesec- ond IFampto maintaina stable audioout- put level.Youcontroloverall receiversen- sitivity with the (front panel) RF gain. Finally,the SSBs VOGADcircuit actslike audio speechcompression,whiletheALC circuit serves double duty in RF speech compre

33、ssion and SWR protection. Overall, the SG-2020s circuitry isslm- pie enough to be understandable, but elaborate enough to do the job without unnecessary shortcuts or compromises. An interior view of the SG-2020s circuit boards,etc.,incidentally,isincludedinthe accompanying photo. The resultant 60 MH

34、zdifference/IFsignal then goes through an FET IF amplifier, through the (two stage) 7 pole/2.7 kHz crystal filter section, through a second IF amplifier, and to a BFO-fed second mixer serving as a product detector. Resultant audiothen proceedsthroughthe SCAFfil- ters, an amplifier, and to the speake

35、r. On SSB transmit, audio from themlcis amplified andcompressed bytheVOGAD section and then applied to the second mixer which acts as a balance modulator andnullsthecarrier.OnCWtransmit, inci- dentally, anunbalancevoltaqeisapplied to this same mixer/balance modulator to produceacarrier.Thetransmitsi

36、gnalthen goes throughthe second IFamp,thecrys- tal filter (drop one sideband to produce SSB),on through the first IFamp and first mixer (which heterodynes the transmit signal down from 60 MHz to 1.8 to 29.7 MHz),and to the transmitters amplifier. This section is shown as onebtcck/tnan- betterthan.51

37、lVfor10dBSfN+N +18dBmthirdorderintercept 100Hzto2700Hz 1wattRMS lessthan3% 5wattsmaximum,4ohms pulse/ignition frontpanelcontrollable processorcontrolled lessthan400ma(receiveonly) 1.8to29.7MHz(U.S.hambandsonly) 1.8to29.7MHz(U.S.hambandsonly) 1.8TO30.0MHz(generalcoverage,export) -30to+70C MC68HC711E9

38、 3ppmper10C(seeexamplebelow 10Hz 100Hz lessthan10ms 20(factorypreset,userdefinable) builtin backlightselectable fullyadjustableiambicmodeB, 5to60wpm adjustable 2.75Hx6Wx7L 4.4lbs. fist,dynamic digital;front-panelcontrolled frontpaneladjustable,0to20wattsPEP VOGADbasebandandRFclipping maximumoutputpo

39、wer,4amperes - 28dBorbetter - 50dB(hambands) USB,LSB,andCW 1.8to30.0MHz,generalcoverage (400kHzt01600kHzwithbroadcastfilter TRANSMITIER Outputpower: RFspeechprocessing: Transmitcurrentconsumption: Transmitintermods.20watts: Transmitspurious: RECEIVER Sensitivity: lnterrnodulation: SelectableAFbandpa

40、ss: Audio output: AFdistortionatnominaloutputpower: Internalspeaker: Noiseblanker: RFgain: BFO: Totalpowerconsumption: Transmitfrequencyrange: Operationaltemperaturerange: Microprocessor: Frequencystability: Frequencyresolution: Frequencydisplay: RxfTxchangeover: Memories: Reflectedpowermetering: LC

41、D: Keyer: Memoryscan: Dimensions: Approximateweight: Microphone: Batteryvoltmeter: bypassed) Specificationsofthe SGC SG-2020 SSB HFTransceiver GENERAL GeneralOperatingModes: Receiverfrequencyrange: lightweightandinsulated-wiredipole aroundthispackage, and youhaveacom- plete work from anywhere statio

42、n. Nice! Circuit Overview As many of our readers will surely agree, investigating a rigs general design con- cept or block diagram gives accurate and unbiased insight into its operating capa- bilities and overall performance. Bearing that thought in mind,lets discuss the SG- 2020s condensed block di

43、agram shown in fig. 1, Starting atthediagrams top leftcorner, incoming signals between 1.8 and 29.7 MHz are first routed to a selected bands low-pass filter,on through a high-pass fil- ter, and to a T/R switching duplexer. The incoming signals then go to a high per- formancefirst mixer,which isalso

44、receiv- ing a 61.8 to 87.9 MHz local oscillator/ injection signal frequency synthesizer. 32 co June1999 SayYouSawIIInCO I , Interior viewofSG-2020 reveals a stouthearted layout with breathing room forcool operation under hot conditions. or-nottun9devoteeswilldiscoverTfRcon- nections lor keying an ex

45、ternal linear amplifier are not included in theSG-2020. bul alas, everything old isnewagain. Just insert a shorting plug in your amplifiers externalT/Asocket and then use its trent- panel standby/operate switch for manual T/Rswitching. It works just as good in Y2Kasitdid in the fabulous 50s. Igaveth

46、e SG2020 a hearty muttiband workout during a recent OX contest and filled twologpageswithcontacts on all continents in less than an hour. The little rigran coolandcalm and handledustlike abigrig.Itis nice! Conclusion Allaspectsconsidered,Iwould saytheSG- 2020 is an outstanding, rugged little trans-

47、ceiver with an affordable price tag. It has more than enough big-time operating fea- tures to please any amateur-at home or in the car. The transceivers operating manual, quick start guide, and support booklets are also well-detailed and very helpful in initially setting up the transceiv- er or a fu

48、ll station. SGC, incidentally. is an acronym for Stoner Goral Corporation, a company foundedby Don Stoner,W6TNS, and Pierre Goral, KI7UA, forthe purpose of producing high-grade communications gear made and serviced in the U.S. The SGC SG-2020 is availableinstand- alone form or with a wide variety of

49、 spe- cial accessories. Suggested retail price of the transceiver alone is $675, or $1195 with itsoptional Portajak front and rear covers/containers. Formoreinformation,contact SGC, 13737 S.E. 26th Street,P.O.Box3526, Bellevue,WA98005(425-746-6310). Themostcompleteselection01cups intheindustry Alsoavailable for2and6 stations W