IC-275_review_CQ_1987.pdf

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1、D The ICOMIC-275 All-Mode 2 Meter Transceiver BY DAVEINGRAM, K4TWJ Fig.1-The ICOM1G-275all-mode2metertransceiver.Unitisquitecompactandulti- matelydeluxe. Evolutionsandexpansions are a nat- ural part of our amateur radio world, and the unit featured in this CO review is a prime example of tnat situat

2、ion. Our mi- gration toward upper spectrum bands continues togainmomentum,with2 me- ters being the center hub of activity. FM and repeater operationskicked off this evolution, then the use ofSSB,globe spanning/Phase IIIOSCARsatellites. and interlinked Packet operations set the band flourishing with

3、action 24 hours a day. The more this trend continues, the more appealing our VHF bands become, and the greater significance all-mode transceivers such as ICOMs newIC275 holdfortodaysamateurs. Measuring3Hx9Wx100, the 1 C.275is size-identical to ICOMspop- ularlc.735HF transceiver. Also, like theIc.735

4、.theres a massive heat sink withinthecabinetsreararea. The cabinet and front panel are flat black, with chrome switches and a brightness- adjustableamberdisplay adding an air of sophistication. The main tuning knob is drag-adjustable.perfectlybalanced, and fittedwitha rubberizedgripfor a pro- fessio

5、nal feel. Theunitsbottomleft row of front controls fit flushwiththecabinet, but they spring out foreasyadjustment when needed. There are actuallytwovariations of this transceiver.The 1C.275Ais a 25watt outputunitwitha built-in AC supply. The 1C.275H is a 100wattoutputunit that re- quires an external

6、 20amp, 13 volt DC supplysuchasICOMsPS55.BothIc.275 versions include a 6-pin rearconnector like those on the 1 G-730, 735. 745, 751, 271, etc., for DC power. Thisplugcom- patibility is quite handy forinstantup- grading or switchhitting in the mobile setup. One day youcanoperate HF, the next day VHF.

7、 etc. Nice! Itsdifficultto pick the 1C.275smost outstanding aspect.butits frequency coverage is agoodstartingpoint.The unit -Eastwood Village No.1201So.RI.77. Box499.Birmingham.AL35210 24COJuly 1987 receives138to174 MHz,whichmeans youcantune all of 2meters,the public- servicefrequencies,mobilephones

8、. pagers,utilities, some weather satellites. plus nationwide NOAA weather stations in the162to163 MHz range.Visualizeus- ing this rig in yourcarduringan emergen- cyorwhile traveling. Youcouldcall for help, shift frequencies.andmonitor am- bulance,police, fire.wrecker,etc. The 1G-275stransmitrange of

9、 140.010 150.0 MHz should also appeal to MARS and CAP enthusiasts interested in deluxe per- formance. If youreconsideringcomput- er control.theresa serial R5-232C con- nectoron the IC-275s rear panel. It uses a 1200baud data rate and allowscontrol of frequency. mode, VFO (AorB) and memory selection

10、via ahomecomputer. Additional IC-275 specifications are in- cluded in Tablel. SpecialFeaturesGalore! The transceiversdual VFOs arecom- plementedby99tunable memories that store frequency,transmitteroffset, and Pltones.Memoriesare selectedby an in- dentedactionMemoknob. The main tuning knob swings any

11、 memory or either VFOacrossthe 1G-275s full frequency range. Remote tuning is also provided with theunitsmikeUP/DOWN but- tons.The overall results are similar to99 VFOs thatrememberfavorite spots when initially selected, plustwoqenerat-our- pose VFOs. Another attraction is the callchannel.Program it

12、withyour fa- vorite frequency,offset,and PL tone, press thebutton.andbingo.yourethere. The unit also includes 32Pltones, and their actual subaudibte frequency (in Hz) can be displayed on thedialsreadout. Standard repeateroffsetsof600 kHz are selected by pressing theDUPbut- ton. Any oddoffsetis avail

13、able by press- ing theSETbutton(offsetthenappears in display). rotating the main tuning knob, then pressingDUPagain to store the preferredoffsetfor that VFO or memory. A fascinating variety of scanning meth- ods are included in the 1C.275. It will scan the full(138to174MHz)spectrum,or you canprogram

14、 limits into specialmemories P1andP2.Itwill alsoscanmemories (non-programmed memories are skipped), orscanby a selectedmode. Constantly busy memories can also be scan-locked Say You SawItInCO 1 6 A . 0 9A Appro . Appro . Appro . Appro,-. 117VAC-t1Q% 240V AC-tlOlo t3,8VDCt 15% At 25Woutput At 2.5W ou

15、tput At.imumaudioOUTPUI andmovedthrough010and on to FL2 or FL4,dependingonthe selectedmode. Take asecond look atthenoisegates circuitry.Samplednoisepulsesgo throughtwoamplifersbeforedetection (andderivingitsownAGC), thentheyre detected,amplified, andused to gate off signalflowfromFL1to010during thep

16、recisetimeofanoisepulse. :U.S.A.ion urO(t,Au.ttllli, v si.,o All version, :U,S,A,9sion138.000-174.000 Europe version144.OO- 146,OOOQMHz AuW, li, ve,sion14 4.OO- 14S,OOOOMHz Specification, guaralltHdfrom143.8000 to 14S.2000MHz. :99ch, n,l, piusPI,P2,n. :6.2k; :- 10C_ 6OC :Fr,(CF3EJ, SS8 1J3El.CWIA1AJ

17、 :2.5 - 25Wconltnuoo.n!y adjunablt :FMV.ir. taroeeffIQUYmodulat,on SS88, Iancedmodul,Ot :tSkHz IFM.,.,.1 :Moretil.6Od9 belowpoeOUTPUt :Moreth.Od9 below pealrouTPUt :MoretIl.Od9downwith lllClClHz AF input :600n , Oouble-conv, ion ,poerhet.rodyne , FM IF3EJ.SS9IJ3EI.CW lAIAI , 10,7!5MHzIFM, SS9)10.749

18、1MHz ICWl 5SkHz IAIlrnoo:!ftJ ,. Ln. th.,O.I/ljlV foo-12d9SINAO Leonwith ansnlot! :! 9.99kHr : sn 14 _3 RECEIVER . Unwanted,;debanCI Microghoneimped_ Table/- General specifications of ICOMs IC-275/ransceiv8rs. _RF output _ . Moduilliontem . Ma. imum-encvdrItion - S(lutiOUOUTPUt _Carrier.,ppra1ion Fr

19、e . . eo - -. oi . i just set the TNCs output level and enjoy. Several other lG-275 operating fea- tures warrant mention. The built-in SWR bridge isgreat.and it beats diggingout a separate unitforantennachecks.Nine- ty-ninememoriesare grand.You can use 15 for utilities, 15 for public services, 15 fo

20、r SSB,20forOSCAR.4for weather, etc. The lG-275 and a mating 2 meter antenna are small and light enough to go any- whereyougo-mobiling, vacationing, anything. Itsa double handful of the goodlife. The1G-275is supported by a full line of complementing accessories. They include the AG-25 preamp, UT-36 v

21、oice synthe- sizer, UT-34 tone squelch,CT-16 satellite mtertacerrlq tracking unit,andFl-83 250 Hz CW filter. Formoreinformation, con- tactICOM America, tnc., 2380116th Street,SW., Bellevue. WA 98004. Paragon-Mounrs Box 21992 l exington, KY 40522 tmues straight aheadto040, the crys- tatoscillatorsFMi

22、ng modulator.That re- sultant signal then makesitsway up to 013and follows the previously outlined RF path10theantenna. I would liketo cover several of the diagrams additional points, butthisreview mightbecometoo lengthy orboring.Dropmea letter with youropinion. Do you prefer or dislike our technica

23、l rap?Should it be longer or shorter? OnTheAir Although the1G-275is quite elaborate, itssurprisingly easy to operate.The first time I useditwas whilemobiling home (whywait?), andIwaschattingonlocal repeaterswhile listeningtoNOAA wea- ther forecastswithintwominutes of turn- on. Installation was a sna

24、p;mylow band 1G-735 was moved to thecarsrear seat, the 1 G-275 was slipped intoitsfrontoosl- *To order:Send $4.00 and a carefullyprintedmailinglabel to: *Addthe crowningtouch toyour radiostationwithaqualityprinted 8x10%inchblackongold paragonlicensemount. IRONPOWDERand FERRITEPRODUCTS AMIociD1ih Fas

25、t.ReliableServiceSince1963 SmallOrdersWelcomeFreeTech.DataFlyer ToroidalCores. ShieldingBeads. Shielded CoilForms Ferrite Rods. Pot Cores. Baluns.Etc. II I I INameI I.ddressI II ICirySf.ifeZip: i_ Now YouCanEnhanceTo Full SignificanceandDisplay Your Hard EarnedAmateurRadiolicenseForAllToSeel Signals

26、 from 01 0 can takeone of three pathsaccording to mode. Thessaroute continuesthrough FL2.theIF notch, SSB filter with itstwin mixers(that establishes passband tuning). 011 and012, the de- tector, squelch, and ontothe speaker. Going back to010, FM signals go down, through1C6,throughFl4, the squelch,

27、and on to the speaker. Tracing the transmit path begins atthe mike (look in diagramscenter), contin- ues through034,035,and on to039and 040.At that point the SSB pathmakesa left turn(follow dotted tine) and moves intotheSSBModemixerlbalance modulator. The DSB signal thenmoves through FL2(exitone sideband, to pro- duceSS8),013.0506(itsthen up-con- verted from a 10.75 MHz to aPt.L-netero- dyned 2 meIer frequency), on tnrouqh 0 3,04, IC1. and to the antenna. Return- ing to039and040, FM-mode audio can- 28CQJuly1987 SayYouSawIIlnCQ