Amateur Radio Technician Class Element 2 Course …4658业余无线电技师班2元课程……

GeneralLicensingClassG0A–G0BElectricalandRFSafetyYourorganizationanddateshere2GeneralClassElement3CoursePresentationELEMENT3SUB-ELEMENTSG1–Commission’sRulesG2–OperatingProceduresG3–RadioWavePropagationG4–AmateurRadioPractices

G5–ElectricalPrinciplesG6–CircuitComponentsG7–PracticalCircuitsG8–SignalsandEmissionsG9–AntennasG0–ElectricalandRFSafety3ElectricalandRFSafetyOnewaythatRFenergycanaffecthumanbodytissueisthatitheatsbodytissue.(G0A01)ThefollowingpropertiesareimportantinestimatingwhetheranRFsignalexceedsthemaximumpermissibleexposure(MPE)

(G0A02)ItsdutycycleItsfrequencyItspowerdensityNeverstandinfrontofamicrowavefeedhornantennaOntransmit,itradiatesahighlyconcentratedbeamofRFenergy

Allofthesechoicesarecorrect.4ElectricalandRFSafetyYoucandeterminethatyourstationcomplieswithFCCRFexposureregulations:

(G0A03)BycalculationbasedonFCCOETBulletin65BycalculationbasedoncomputermodelingBymeasurementoffieldstrengthusingcalibratedequipment"Timeaveraging"inreferencetoRFradiationexposuremeansthetotalRFexposureaveragedoveracertaintime.(G0A04)Thegeneralequationfortimeaveragingexposureequivalenceis:Sexp

texp=Slimit

tavgAllofthesechoicesarecorrect.5ElectricalandRFSafetyIfanevaluationofyourstationshowsRFenergyradiatedfromyourstationexceedspermissiblelimitsyoumusttakeactiontopreventhumanexposuretotheexcessiveRFfields.(G0A05)(G0A06–DeletedbyQPC)WhenevaluatingRFexposure,alowertransmitterdutycyclepermitsgreatershort-termexposurelevels.(G0A07)

AnamateuroperatormustperformaroutineRFexposureevaluationtoensurecompliancewithRFsafetyregulationswhentransmitterpowerexceedslevelsspecifiedinpart97.13.

(G0A08)DutyCycle6ElectricalandRFSafetyAcalibratedfield-strengthmeterwithacalibratedantennacanbeusedtoaccuratelymeasureanRFfield.(G0A09)

JerrodModel704BElectro-metricsem-7530HomebrewbyKA7OEIofUtahAmateurRadioClub7ElectricalandRFSafetyIfanevaluationshowsthataneighbormightreceivemorethantheallowablelimitofRFexposurefromthemainlobeofadirectionalantenna,takeprecautionstoensurethattheantennacannotbepointedintheirdirection.

(G0A10)Ifyouinstallanindoortransmittingantenna,makesurethatMPElimitsarenotexceededinoccupiedareas.(G0A11)

MPE=MaximumPermissibleExposureTurnoffthetransmitteranddisconnectthefeedlinewheneveryoumakeadjustmentsorrepairstoanantenna.(G0A12)8ElectricalandRFSafetyWheninstallingaground-mountedantenna,itshouldbeinstalledsonoonecanbeexposedtoRFradiationinexcessofmaximumpermissiblelimits.(G0A13)Onlythehotwiresinafour-conductorlinecordshouldbeattachedtofusesorcircuitbreakersinadeviceoperatedfroma240-VACsingle-phasesource.(G0B01)Noticewoodsafetyfence.

Keepasafedistanceawayfromantennaduringalltransmissions.9ElectricalandRFSafetyAccordingtothecode,AWGnumber12istheminimumwiresizethatmaybesafelyusedforacircuitthatdrawsupto20amperesofcontinuouscurrent.(G0B02)

15amperesisthesizeoffuseorcircuitbreakerthatwouldbeappropriatetousewithacircuitthatusesAWGnumber14wiring.(G0B03)10ElectricalandRFSafetyDangerofcarbonmonoxidepoisoningisaprimaryreasonfornotplacingagasoline-fueledgeneratorinsideanoccupiedarea.(G0B04)

CarbonMonoxideisseriousstuff,don’ttakeitlightly!11ElectricalandRFSafetyCurrentflowingfromoneormoreofthehotwiresdirectlytogroundwillcauseaGroundFaultCircuitInterrupter(GFCI)todisconnectthe120or240VoltAClinepowertoadevice.(G0B05)

12RF&ElectricalSafety13ElectricalandRFSafetyThemetalenclosureofeveryitemofstationequipmentmustbegroundedbecauseitensuresthathazardousvoltagescannotappearonthechassis.(G0B06)

Enclosures,chassis,andallmetalhousingsshouldbecommongrounded.14ElectricalandRFSafetyOneofthepracticesthatshouldbeobservedforsafetywhenclimbingonatowerusingasafetybeltorharnessistoalwaysattachthebeltsafetyhooktothebeltD-ringwiththehookopeningawayfromthetower.

(G0B07)

Alwaysdisconnectthefeedlinefromthetransmitterbeforegoingupatowertoworkonantenna…preventsaccidentalRFradiationexposure.Alwaysthinksafetyfirstwhenworkingontowers.15ElectricalandRFSafetyAnypersonpreparingtoclimbatowerthatsupportselectricallypowereddevicesshouldmakesureallcircuitsthatsupplypowertothetowerarelockedoutandtagged.(G0B08)Solderedjointsshouldnotbeusedwiththewiresthatconnectthebaseofatowertoasystemofgroundrodsbecauseasolderedjointwilllikelybedestroyedbytheheatofalightningstrike.

(G0B09)

Onedangerfromlead-tinsolderisthatleadcancontaminatefoodifhandsarenotwashedcarefullyafterhandling.(G0B10)16ElectricalandRFSafetyGoodengineeringpracticeforlightningprotectiongroundsincludesbondingthemtogetherwithallothergrounds.(G0B11)

Noticegreencableascommongroundunderfloorandconnectedtobuildingcolumn.Noticewidecopperstraps17ElectricalandRFSafetyThepurposeofatransmitterpowersupplyinterlockistoensurethatdangerousvoltagesareremovedifthecabinetisopened.(G0B12)

Whenpo