IC-718_review_2001.pdf

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1、CQReviews: The ICOM IC-718 HF Transceiver BY DAVEINGRAM:K4TWJ PhotoA-ICOMsnewIC-718packsasurprisingamountofbig-timeperformance intoanexceptionallysmallcase. Thetransceivercanalsobetailoredtoyourown operatingpreferenceswithoptionalaccessoriesasdiscussed intext.(Photocour- tesyICOMAmerica, Inc.) W hat

2、 would you consider more fun and exciting than chatting with good friends and working DX with a room full of fancy gear? How about doingitwith a brand-new, low- costHFtransceiverthat is smallenough to sit on a nightstandbyyour favorite easy chair and sports a numberof big- rig features to boot? Well

3、, friends, that is exactly what I have been doing recently with ICOMs newIC-71B,and Iwillbet a similar change of pace will add some new- found enjoyment to your life, too. How so? First, it is the famous old story of a special friend or a rare OX station that always hits the airwaves two minutes aft

4、er youwalkoutofthe shackorgive up trying to copyweak,QRMedsignals on a well-used andsomewhat outdated transceiver. Second,thereis unique radiomagicin working the world with a neat little rig that mustbeexperienced first hand to be fully appreciated. Life is a one-shot deal.Whyshort- change yourself

5、whennewtransceivers such as ICOMs IC-718 offer such high performanceatsuchanattractive price?! The sunspotcount is high, and the HF bands are better than they have been in a numberofyears.Geton the air and enjoy hammingto themax! I hearyou asking, Whatis specialabout the IC-718 and what makes it att

6、ractive for HFingTThat will take a few pages toexplain, sobepatient and read on! Hey,LookMe Over! Right fromthe first glance, theIC-718s 4 x 9.5 x 9 cabinet and front LCD- screen-typedisplayproduce a most favorable and genuineICOM appear- ance (photo A). Indeed,thetransceiver looks like a miniature

7、IC-781,IC-746,or IC-756.Onlythreeofficialknobsgrace the frontpanel:AFand RF volume! squelch, RIT and IF Shift, and main tun- ing. Frontpush-buttons temporarily as- 4941Scenic ViewDrive,Birmingham,AL 35210 e-mail: k4twjcq-amateuN 52.COJanuary2001 sign various other functions to the main tuning knob,

8、however, producing the equivalentofa 30-or40-knob rig. Lets step back a minute and review The IC-718sbasicattractions. The transceivercovers160 through10 meters with 5to 100 wattsoutputonCW andsse(40wattson AM),includes 300 kHzto 30MHzshortwavereception, and sports 101 tunablememories. Ad- ditional

9、specsandtechnicaldetails are shown in fig. 1. Big-rig features include dual independent VFOs, split-frequen- cy capability, band and memoryscan- ning,SWR metering,VOX, speech compressor, semi and full a SK (break- in),CWkeyer,andnoise blanker. It strikes me as a lot of rig forthe money, andits inclu

10、sion of a front-facing speak- erplusSWRmonitor and keyer results in acompactone box unit that fits almostanywhere. All you need toget on the air with an IC-718 is a micro- phone(a hand mic is supplied), key, antenna, and a 13 voltDC! 20amp (peak current) powersupplyorauto- mobile battery for mobilin

11、goroutback- ing.Thetransceiverisfitted with a stan- dardICOM/Kenwood-type6-pin DC socket, andthe rearpanel is flat with- out heat sinkorfan protrusions. Like otherpopular-modeIICOMs, the IC-718s front-screen-type display indi- cates frequencies and modes in its up- per area, while a barograph-type m

12、eter in its lowerarea indicates received sig- nallevels,output power,SWR, and ALC (fig. 2). Thebargraph also includes a peak hold function that freezes maxi- mum level readings for approximately one second and makes them easy to read. Nice!When theIC-718s menu set is punched up, thedisplaychanges to

13、 indicate a selected featureorfunction, and adjustmentsaredisplayed on the bar graph as you rotatethetuning knob (fig. 3).This direct readoutofselected adjustmentsisquite handyanduser friendly, and it surebeats trying to re- memberthe rigs full menu set or look it up in themanual during aaso. That i

14、s not criticizing the manual; it is very VisitOur Web Site Specifications ofthe ICOMIC718 HFTransceiver Double conversion superheterodyne system SSB. CW. RTTY 0.161JV(1.8-29.999999 MHz) AM 13IJV (0.5-1.799999 MHz) 2IJV (1.8-29.999999 MHz) SSB, CW, RTTY -less than 5.6IJV SSB, CWoRTTY More than 2.1 kH

15、zJ-6dB l ess than 4.5 kHzI-60 dB AM More than 6 kHzI-6dB lessthan 20kHzI-40dB More than 70 dB (1.8-29.999999 MHz) :t:1200 Hz More than 2.0 W at 10% distortion with an 8 ohm load 3-conductor 6.35 (d) mm(1/4in.) 2-conductor 3.5 (d) mm (1/8in. 8 ohm Squelchsensitivity: (threshold) Selectivity: Sensitiv

16、ity: Modulationsystem:SSB -balanced modulatiOn AM -Low-level modulation Spuriousemissions:less than -SOdBbelOwpeak output power Spurioustree.:below30MHz. -SOdB;above3041Hz.-60dB Carriersuppression:More than 40 dB Unwantedsideband:More thanSOdB Microphoneconnector:8-pin (600 ohms) Keyconnector:a-ccno

17、octor6.5(d)mm(1/4in.) SEND/Aleconnector:Phono (RCA) RECEIVER Receivesystem: Spuriousandimage rejectionratio: RITvariablerange: Audiooutputpower: (at 13.8 VDC) PHONESconnector: External SPconnector: SSB,CWoRTTY -5-100 W AM-2-40W GENERAL Frequencycoverage:Receive 0.03-29.999999 MHzl Transmit 1.800-t .

18、999999 MHzz 3.500-3.999999 MHzz 7.000-7.300000 MHz 10.100-10.15OOMHz 14.000-14.35OOMHz 18.068-18.168000 MHz 21.000-21.450000 MHz 24.890-24.990000 MHz 28.000-29.700000 MHz ./ Guaranteedrange: 0.5-29.999999 MHz 2Vanes according to version. Mode:USB,lSB, CW,RnY, AM Numberofmemorychannels: 101(99regUlar

19、. 2 scan edges) Frequencystability:lessthan :t:200 Hz from 1 min. to 60min. after power on. After that. rate01stability less than:t:30 Hzlhr. at +25C (+7rF). Temperature fluctuations O C to-so-c(+32F to +122F) tess than:t:3S0Hz. 13.8VDC:t15% (negativeground) Receive standby 1.3 A Receive max. audio

20、2.0 A Transmit max. power 20.0 A - 1DOC1 0+60C; +14F to +140F 50-239(SOohms) 240 (W)(95 (H)x239(D)mm 97/16(W)x33/4 (H)x913/32(D)in. 3.8 kg (8 lb. 6 oz.) 13-pin 2-oonductor 3.5 (d) mm (1/8 in.) Power supplyrequirement: Currentdrain(at 13.8VDC): Operatabletemp.range: Antennaconnector: Dimensions: (pro

21、jections not included) Weight(approx.): ACCconnector: REMOTEconnector: TRANSMITIER Outputpower: Fig.1-Generaltechnical specificationsoftheIC-718. Fig.2-Ashowairanalysis of the IC-718sfront-screendisplay. The screen showsselectedfrequencies,memories,andalloperatingparameters,plusamulti- function bar-

22、graph-type meter. ,_._., ( IE3:ILSBUSBCWRTTYAMmIIImD J):_.H._U._._._._: :TUNEI:_Jl JlJlJlJlJlJiJ! RI:b,_BIK:(cQJs,tffii! IOSP:-.si-3-,-t-U20-u -i6cii;YFCIBLANKI _ IIANFt, Ri iiii i ii i ii iii i i i i i iii iiiii i ir.-E.ABr,r,II (;ftl,._0000.-.-.-._ .-._ .-,.-, : l!fu :1011.520 23so00100:. -_:.:-.:

23、.:.:- -:.:.:,.:.:.:- -.-1 - easy1 0understand and use.On-screen guidance is just moreconvenient and time-effective. Special Features Due to its small size and low cost, many folks tend to visualize the IC-718 as a ratherplain Janetransceiver. Look closer, however, andyou will discover it sports some

24、 ratherelaborate features andoptions for a rigofits price range. TheIC718snoise blanker, forexam- ple, is fully adjustable to fit varyingband conditionsrather than just being preset. AnFSK generatorcomplete with seiec- table tonesof2125, 1615, and 1275 Hz plus shifts of 850, 425, and 170 Hz is also

25、included for RTTY/data mode op- erations. Extemal linear amplifierT/R switching has also been streamlined to anRCAphonesocketwith theIC718s relay directly switchingupto 16 volts DCat2amps.Anextemalswitchboxor interfacethus is notneededfor con- nectiontomost linearamplifiers. A choice of five optiona

26、l 455 kHzIF fil- ters lets you tailor the IC-718 toyour operating preferences. If CW or RTTY is your main interest, for example, you can add a 500 Hz!FL52A or a 250 Hz!FL53A in the rigs optionalcrystal slot. A 250 Hz filterusually requires an extra-steady hand for tuning in signals and also has slig

27、htlymore insertion loss.so mostfolks choose a 500 Hz filter. If SSB is your favored mode, you can add a wide 2.8 kHz!FL96,a verynarrow 1.8kHzlFL222, or an ultra-wide and great-sounding 3.3 kHzlFL257 in the IC-718s single option- al filter slot. The tactory-mstalled/stan- dard FL65 filter, incidental

28、ly, is 2.4 kHz www.cq-amateur-radic.ccm January2001CO53 Fig.3-Here you see two examplesofhow the IC-71Bs display looks when a menu-selected functioniscalledupfor adjustment. .- .-. 7: :5r I,J,: ,-ti ,!r-;i.-lJ11i ,.roI: : i,y1 ,1/1,1 ,/1-,i Jt:,- z : z ; .It i I ! . . -o B _!I-1Ir- l ,.j.l., :!.!.:

29、, I- . .i! I I January2001CO55 gram)routesthroughthemicampl speechcompressorNOX (IC2201), throughanaudio-range filter,andinto the balanced modulator (IC2301). As- sumingssemode is selected, a dou- ble sideband and suppressedcarrier signal is output and routed back the opposite way throughFL65(dropon

30、e sideband to produceanssesignal), andon through transmit IFamp0502. Thesignal is thenup-converted by 0401.passedthrough F11301 . and convertedto the transmit frequencyby 0101and0102. It thenproceeds through IC1, 01. drivers Os and03, powerampsQ4and05. transmit fil- ters,andonthrough theT/Rrelay to

31、the antenna. The previous description should familiarize you with the IC-718 sufficiently forgeneral understanding, soI will let you take it from there and delve into additional study as you like. PhotoB-fCOMsoptionallC-PW1 alf- sofid-state, fully automatic 1000 watt outputlinearamplifierandantenna

32、tuneris theperfectfinishingtouch tothe IC-718 (orotherICOMtransceivers).It is trufy first class! Conclusion Allaspectsconsidered, the IC-l18 strikesme asa very good little HFtrans- ceiver at a fair and square price. It is not an IC-756 Pro,but Iwillbetasharpoper- atorcan work anything with it he!she

33、 could work with a756 Pro.Icannot nec- essarily say the same for transceivers from20or30years ago, however, as newgeneration rigs really do receive and transmit better than much of the older gear. Viewed from those stand- points, the IC-718 getsmyvote for affordable rig of the day. For more informat

34、ion on the IC-718 andother ICOM gear, contact ICOM America, Inc., 2380-116th Ave.N.E., Bellevue,WA98004 phone 425-454- 8155; web: . If you really want blow-away sound- ing audio, one finalandsomewhat exotic mic-eomplementing idea war- rants quick mention. Consider replac- ing the IC-718s 2.4 kHzlFL6

35、5 filter, which is common totransmitandre- ceive,with a 3.3 kHzlFL257 filter. This is a technicalenoeevor.umay not be a quick and easy swap, and if improperly done it may void the rigs warranty, but it (plus a Hell microphone) should pro- duce totally exquisite audio seldom (if evert) heard on SSB.

36、Inside Views Ifyou have been following ourbt-monm- Iy How It Workscolumn here inCO, you know that looking at a transceivers block diagram is one of the most effec- tive and impartial means of visualizing its operation and performance. Bearing that thought in mind, lets take a whip- lash inside tour

37、of the IC718. Refer to fig. 4 as we proceed. Beginning at pointAon the dia- grams right middle side, incoming/re- ceived signals are first routed from the T/Rswitch through one of several CPU- selected bandpass filters foryour de- sired receive range. Signals then pro- ceed through apanel-selectable

38、preamp (0 1401 and01402) and are up-con- verted to a first IF of64MHz by the first mixer (0 1101 through01104). A local oscillatororinjection signal between 64.485 and 94.455 MHz (depending on yourdesired operating range)isderived from one of the two PLL (Phase Locked Loop) units in the DDS (Direct

39、Digital Synthesis) to drive this mixer.The DDS acquires its exact trequency-determin- ing data from the CPU, whichin tum accepts input datafrom the 10- key pad or main tuning dial. Retuming to the first mixer,64MHz output signals then pass throughceramic filter FL1301 whichlim- its bandwidth to 15 k

40、Hz (because this filter must pass AM plus both USB and LSB signals). The received signal is amplified,converted to a 455 kHz sec- ond IF by second mixer D401 ,and rout- ed through the factory-installed FL65 or an optional SSB, CW, or AM filter. (This is the spot where I hinted at filter swaps earlie

41、r.)Thesignalthenproceeds through second IFs01603,01602, buffer 01601 .and into product detector IC2001. Resultant audio from01602 then proceeds through AF selector IC2102, through AF amp IC2101 and IC2901. and on to the speaker. During transmit.audiofromthemic- rophone (point 8onleft sideof dia- SAM

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