detectorsarerenownedfortheirquality.EachdetectorishandcraftedintheUSAwithpride

P E R F O R M A N C ETheworldwideundergroundutilityindustryreliesonFisher®.

Ourinstrumentsaredurable,dependable,andlocatedeeper.

R E P U T A T I O NFisherproducedthefirstpatentedmetaldetectorin1931.Forover80years,theFisherlogohasbeenamarkofexcellence.

5 - YEAR LIMITED WARRANTYRegister your warranty on-line for a chance to win a

FREE DETECTOR.For details, visit www.detecting.com

Fisher®believesintheproductsweproduceandbacksthisbeliefwitha5yearlimitedwarranty.

Proof of purchase is required to make a claim under this warranty.

NOTE TO CUSTOMERS OUTSIDE THE U.S.A.Thiswarrantymayvaryinothercountries,checkwithyour

distributorfordetails.Warrantydoesnotcovershippingcosts.

S E R V I C EFisheriscommittedtoprovidingyou,ourvaluedcustomer,with

FISHER RESEARCH LABORATORY1465-HHenryBrennan,ElPaso,Texas79936

Tel915.225.0333Fax915.225.0336www.fisherlab.comemail:info@fisherlab.com

AccordingtoFCCpart15.21ChangesorModificationsmadetothisdevicenotexpresslyapprovedbythepartyresponsibleforcompliancecouldvoid

theuser’sauthoritytooperatethisequipment.

Gemini-3

Operating Manual

2-Box Metal and Mineral Detectorfor Deep Search and Cache Locating

8703520000 Rev.2 091813

Q U A L I T YFisher

CONTENTSAbout Your Gemini-3 ............................................................... pg. 3Basic Theory of Operation ....................................................... pg. 4Depth

....................................................................................pg. 7

Searching ..................................................................................pg. 8 Narrow Scan Inductive Search ........................................... pg. 8 Set Up .............................................................................pg. 8 Tuning .............................................................................pg. 9 Operation ...................................................................... pg. 10 Wide Scan Inductive Search ............................................... pg. 12 Set Up .............................................................................pg. 12 Tuning .............................................................................pg. 12 Operation ...................................................................... pg. 13Tracing .......................................................................................pg. 14 Inductive Tracing.................................................................. pg. 14 Set Up .............................................................................pg. 14 Tuning .............................................................................pg. 14 Operation ...................................................................... pg. 15 Conductive Trace ................................................................ pg. 15 Set Up .............................................................................pg. 15 Tuning .............................................................................pg. 16 Operation ...................................................................... pg. 16Prospecting Tips ........................................................................ pg. 17 Mapping ................................................................................pg. 17 Locating Placer Deposits ..................................................... pg. 17 Sources of Error ..................................................................... pg. 18Battery Replacement ............................................................... pg. 19Treasure Hunters’ Code Of Ethics ............................................ pg. 20Where To Use Your Metal Detector In The U.S. ...................... pg. 21Specifications ...........................................................................pg. 22Using Headphones ................................................................... pg. 23

23

Notes

1. Subjecttoimprovementormodificationwithoutnotice.2. Approximate.3. VoltageControlledOscillator.Volumeandpitchbothincreaseastargetisapproachedforeasier,moreaccuratepinpointing.4. Withoptionalgroundplateassembly.5. Optionalstereo/monoheadphones.6. Useofheadphoneswillsignificantlyincreasebatterylife.

FisherResearchLaboratorydoesnotwarrantsuitabilitytospecificuse.FisherResearchLaboratoryshallinnoeventbeliable for any direct, incidental, consequential or indirectdamages.

SPECIFICATIONS

Usingheadphones(notsupplied)improvesbatterylife,andpreventsthesoundsfromannoyingbystanders.Italsoallowsyoutohearsubtlechangesinthesoundmoreclearly,particularlyifsearchinginanoisylocation.Forsafetyreasons,donotuseheadphonesneartrafficorwhereotherdangersarepresent.Thisdeviceistobeusedwithinterconnectingcables/headphonecablesshorterthanthreemeters.

USING HEADPHONES

........................................................................................pg. 5Transmitter .................................................................................pg. 6Receiver

22

SPECIFICATIONSDimensions

Lengthonhandle............................................................491/2inchesTransmitter-ReceiverBoxAssembly.................................................91/4x12x6inches(23.5x30x15cm)

Weight Complete...........................................................................7lbs.(3.2k)Transmitter........................................................................2.4lbs.(1.1k)Receiver...........................................................................2.9lbs.(1.3k)Handle..............................................................................1.7lbs.(.75k)

FrequencyRFSearchandTrace............................81.92KHzCrystalControlled.................................................AudioTargetResponse(VCO)

Operating Modes Search 1.NarrowScan,Inductive 2.WideScan,InductiveTrace 1.Inductive 2.Conductive

Target ResponseMeter...................................................... 21/4x13/4inches,AnalogSpeaker............................................................21/4inches,100ohm,MoistureProofConeHeadphones.......................................... 1/4inchJack,8-16ohms,

............................................................................................Stereo/Mono

Batteries Receiver.............................................................................. (8)AA1.5VTransmitter.......................................................................... (8)AA1.5VLife...........................................CarbonZinc............................ 30Hours

.................................................Alkaline.................................... 50Hours

2

3

4

5

62

3

ABOUT YOUR DETECTORTwo-box metal detectors have long been used by

prospectors, geologists, treasure hunters and public utilitycompanies to locate large,deepobjects,orevein,pipesandcables. FisherResearchLaboratory is the recognizedleaderinthefield,infact,theyweregrantedthefirsttwo-boxmetaldetectorpatentover60yearsago.

Youmightthinkitwouldbedifficulttoimproveonaproductthathasbeeninaconstantstateofdevelopmentforsomanyyears.Butthefactis,theGEMINI-3isprobablythebiggestleapforwardintwo-boxdesignsinceit replacedvacuumtubeswithtransistorsbackinthe1950s.

ThenewGEMINI-3goes10to20percentdeeperthanitspredecessor.Itwilltracemostpipesandoreveinsatleast50percentfarther,andthenewcrystalcontrolledcircuitryis rock stable. The old metal-rim antenna is gone and soarethehard-to-getbatteries.TheGEMINI-3iseasiertouse,twopoundslighter,&featuresVoltageControlledOscillator(V.C.O.),audiotargetresponseforprecisionpinpointing.

YourFisherGEMINI-3isahighquality,precisioninstrumentengineered by the oldest and proudest name in metaldetectors.Treatitright,readthisinstructionmanualthoroughlyandpracticeoften.Whoknows,withskill,patienceandalittleluck,youmayfindtheBIGONE.

Drop us a line if you have any questions, comments orexcitingGEMINI-3stories.Inthemeantime...

Happyhunting,FISHERRESEARCHLABORATORY

4

BASIC THEORY OF OPERATION The GEMINI-3 was engineered to detect conductivitychangesintheearthoverwhichitiscarried.Hence,apositiveresponsebytheGEMINI-3indicatesthepresenceofametalobject,oreveinormineralthatismoreconductivethanthesurroundingrockorsoil.

ThefunctionoftheGEMINI-3Transmitteristosendaradiofrequency (RF) signal down to a conductive object andgenerate an electromagnetic field around that object.When used in any of the Inductive modes, the RF signaltravels through the ground to the object. When used inthe Conductive Trace mode (see page 15), the signal istransmitteddirectlythroughawireattachedtoanexposedportionoftheobject.

The function of the GEMINI-3 Receiver is to locate theobjectbydetectingtheelectromagneticfieldarounditandrespondingwithaudioandvisualsignals.

21

National Forest and Federal Lands—Metaldetectingisallowedonlybyspecialpermitacquiredfromthefederalgovernment.Eachareahasadistrictoffice.

Corps of Engineers, Lakes, Shorelines and Lands—Permissionhasbeengrantedonlyonpre-disturbedsites,suchasbeachesandattachedswimmingareas.NewCorpslakesandlandsmustbeokayedbythemainofficeoftheArmyCorpsofEngineers.Eachareahasadistrictoffice.

State Parks and Lands—Somestateparksareopentometaldetecting,butsomearenot.Alwayscheckwiththeparkrangerbeforeattemptingtouseyourdetector.

Bureau of Land Management (BLM) Lands—Someareasareopenformetaldetecting,andsomearenot.Alwayscheckwiththedistrictoffice.

City or County Park Lands—Mostareopentometaldetectingunlessnoticeisgivenbyasignorcityordinance.Whenindoubt,alwayscheckwiththecity’sParksandRecreationDepartment.PublicSchoolGrounds—Mostareopentometaldetectingunlessnoticeisgivenbyasign,cityordinance,lawenforcementofficial,orschoolemployee.Youshouldalwayscheckwiththeschoolofficefirst.

Privately Owned Lands (Private Property)—Permissionrequired.Itisalwaysbesttohavethepermissioninwriting.

Historically Marked Lands or Sites—Metaldetectingisnotallowed.Don’teventhinkaboutit.

Where To Use Your Metal Detector In The U.S.

5

DEPTH TheGEMINI-3wasdesignedtolocatelarge,deepobjectssuchasanironchest,pipeoranorevein.Itwillnotdetectsmallcoin-sizedobjects.Aquartjarfullofcoins,however,maybedetectedone-to-threefeetdeep.A55-gallondrummaybedetectedasdeepas10feet.Averylargeobject,likeanautomobile,maybedetectedat20feetormore. TheabilityoftheGEMINI-3todetectobjectsatvariousdepthsdependsonseveralfactors:

1. Ground Mineralization:ThepenetratingpoweroftheGEMINI-3isadverselyaffectedbythepresenceofmagnetite(ablackironoxide)andwetconductivemineralsalts.Forexample,anobjectthatcanbedetected at 15 feet in neutral ground may bedetectednodeeperthan5feetinhighlymineralizedground.

2. Size and Depth of Object:A4-inchdiametertargetwillproducesignal64timesstrongerthanasimilar1-inchdiametertargetatthesamedepth.Anobject1-footundergroundwillproduceasignal4,000timesgreaterthantheobject4feetdeep.

3. Length of Time Object is Buried:Anobjectthathasbeenburiedforalongtimemaybeeasiertodetectthananewlyburiedobject.Rustandotheroxidesaswellasmineralizationcausedbytheinteractionofthemetalwithsoilchemicalsaregoodconductorsandaiddetection.

4. Shape of an Object:Ringorloopedshapedobjectslyingflatproducethebestresults.Flatordishshapedtargetsarealsoeasytodetect.Rodshapedobjects,especiallywhenscannedonend,areverydifficulttodetect.

5. Operator Skill:Probablythemostimportantfactorof

all,practiceoverknownburiedtargetsisessential.

20

LET’S PRESERVE OUR TREASURED SPORT!

Lawsgoverningtheuseofmetaldetectorsarecommoninsomeareas.Inmanycountries,theuseofmetaldetectorsisillegalorseverelyrestricted.DON’TLETTHISHAPPENINYOURCOUNTRY!

•AlwayscheckFederal,State,Countyandlocallawsbeforesearching.

•Respectprivatepropertyanddonotenterprivatepropertywithouttheowner’spermission.

•Takecaretorefillallholesandleavenodamage.•Removeanddisposeofanyandalltrashandlitterfound.•Appreciateandprotectourinheritanceofnaturalresources,

wildlifeandprivateproperty.•Actasanambassadorforthehobby,usethoughtfulness,

considerationandcourtesyatalltimes.•Neverdestroyhistoricalorarchaeologicaltreasures.•All treasurehuntersmaybe judgedby theexampleyouset;

always conduct yourself with courtesy and consideration ofothers.

LET’SPRESERVEOURTREASUREDHOBBY

TREASURE HUNTERS’ CODE OF ETHICS

TRANSMITTER

BatteryLevelMeter

PowerSwitch GroundPlateJack

Figure 2. Transmitter

Power Switch: Pulloutswitchturnsonpower.

Ground Plate Jack:UsedwiththeoptionalGroundPlateAssembly

fortheConductiveTraceMode.

Battery Level Meter:Givesavisualindicationofbatterystrength.

Replacebatteriesifbelow5onmeter.

6 19

BATTERY REPLACEMENT1. Turneitherinstrument(TransmitterandReceiver)over

onitsfaceandremoveaccessplatewithcoinorlargebladescrewdriver.

2. Lift thebatterypackoutcarefully.Turnthebatterypackslightly,unsnapthebatteryconnectorandslipoff the sleeve.Changealleightbatteries. Slip thesleevebackon,thenreattachtheconnectortothepack.Slipthebatterypackbackintoitscompartmentanddoabattery test.Refasten theaccessplate.Boththetransmitterandreceiverwillworkfrom30to40hoursonasetof8standardquality,carbon-zincbatteries. Alkaline batteries will give substantiallylonger lifeand incoldweatherwillperformmuchbetterthanstandardcarbonzincbatteries.

NOTE: As supplied from the factory, the battery pack is surrounded by a plastic sleeve to retain the batteries during possible rough handling and shipping. As a precaution, always reinstall the sleeve after battery replacement.

Figure 10.ChangingBatteries

RECEIVER

Speaker: Provides audible indication of the receiver signal for

balancinganddetecting.

Meter:ProvidesvisualindicationoftheReceiversignalresponsefor

balancinganddetecting.Alsousedasabatterytestindicator.

Sensitivity Control:Usedtocontrolsensitivitylevel.Thecircled“7”

indicatesthestartinglevelusedforNarrowScanInductiveSearch

Mode.

Headphone Jack:Acceptsstereoormonauralheadphonesand

silencesspeakerwhenheadphonesarepluggedin.(Stereo/mono

headphonesshouldbein“stereo”position.)

Power Switch: Pullingswitchoutturnsonreceiver.

Meter

SensitivityControl

HeadphoneJack

PowerSwitch

Speaker

Figure 3.Receiver

BatteryTestSwitch

718

PROSPECTING TIPS

Sources of Error The most common nonproductive zones ofconductivityare:

1. Dissolved mineral salts - Mineral salts becomeconductivewhendissolvedinwater.Asaresult,thepresenceofsalinewaterorwatersaturatedsoilhighinsaltcontentmayrendertheGEMINI-3useless.

2.Rough terrain-Inveryroughterrainitmaybedifficultto maintain the GEMINI-3 parallel to the ground,resultinginfrequentfalsesignals.

3. Irregularities in the overburden bedrock -TheGEMINI-3maydetectsharpchangesinconductivitywhichareofnoimportantgeologicalsignificance.

4. Fault zones -Faultzonesoftengivepositiveindicationsbecausetheyarehighlyfracturedandusuallycontainconcentrationsofwaterandminerals.

5. Alluvial deposits along creek bottoms - Conductivedepositsalongcreekbedsusuallyhavenoeconomicvalueorimportanceindeterminingthegeology.

6. Conductive debris -Unexpectedhighreadingsareoften due to highly conductive debris near thesurfacesuchasscrapiron,tincans,etc.

7. Magnetite - Heavyconcentrationsofmagnetitewillcausefalsesignalsand/orlossofpenetratingpower.

It isobvious fromtheabovethatevery responseby the GEMINI-3 does not indicate the presenceofvaluableore,but ratheran indication that theearth’sconductivityhaschanged.Itremainsfortheoperatortoproperlyinterpretthisdata.Thesuccessfulprospectorwillhavesomeunderstandingoftheoreheisseekingandoftheexistinggeologicalconditions.The successfuloperatorwillalsohavestudied thatareaandwillknowinadvancewhatoreheisseekingandwherethebestopportunityexistsforlocatingit.Under theseconditions, theGEMINI-3canprovidevaluable information.On theotherhand, randomwanderingandprospectingfornooreinparticularcanbeanexpensivewasteoftime.

8

SEARCHING

Narrow Scan Inductive Search Thismodeofoperationisperformedbyasingleoperatorusingthe3-piecehandle.Itisthebestmethodforlocatingsmallorshortobjects(chest,coin-jar,rifle,etc.).However,itisalsoaneffectivewaytolocatepipes,cablesandoreveins.Set Up

1. Assemblethe3-piecehandlebyinsertingeachendpieceintothecenterhandlesection.Tightenthetwocenterknobsfingertightuntilthereisnowobble.PlacethetransmitteronitsbackandinserttheendofthehandlewiththesinglebrassshaftintotheV-shapedslot.Turntheknobuntilitisfingertightandthehandleisfirmlyintheslot.

2.Alignthereceiverpanelholeswiththeupper-handlethreadedshafts.Tightenthelowerblackknobuntilitisfingertight.

3.Turnthebalanceknob(withwhitearrow)untilthespringisundertension(atleast10turns).

Figure 4.NarrowScanInductiveSearch

Figure 5.AssemblyforNarrowScanInductiveSearch

17

PROSPECTING TIPSMapping

Whenanareaofhighconductivityisencountered,outline and stake it by crossing and re-crossing,using theNarrowScan Inductive Searchmode. Itwillbenotedthatinandneartheconductivezone,amaximumindicationwillbereceivedinonlyonedefinitedirectionwhentheoperatorstandsatonepointandrotatestheinstrumentparalleltothesurfaceoftheground.Recordthemeterreadingsasreadin themaximumdirections,atvariouspointsalongthe zones.Note thecharacterof theoverburden,outcropsandtopographicfeatures. Whentheareabeinginductivelysurveyedhasbeencompletelycoveredandalloftheconductivezoneshavebeen staked, these zonesare surveyedandplottedonamap.Themapshouldincludeallcreekbottoms,gullies,outcropsandotherphysicalfeatures.Theidealmaponwhichtoplottheconductivezonesisatopographicandgeologicalmapoftheproperscale.Inthiswayitispossibletocorrelatethezonesdirectlywiththetopographyandgeology,andthusdeterminethepossiblereasonsforthepresenceofthevariousconductivezones.

Locating Placer Deposits Alotofprospectorshavetoldustheywouldliketouseatwo-boxforlocatingplacergold.Ingeneral,thesedepositscontainsuchasmallamountofgoldthat itcannotbedetected.Placergold,however,isusuallyassociatedwithacertainamountofblacksand,andsomeplacerdepositscarryironsulphide.Both of these mineral substances are definitelyconductive,andmaybedetectedbytheGEMINI-3.Itisthroughthedetectionofthesemineralsthattheplacergoldmaybelocated.

9

Tuning1.Setthetransmitter: Power:ON

2.SettheReceiver: Power:ON Sensitivity:7 You should get a strong audio tone and meter

indicationatthispoint.CAUTION:NeverattempttotunetheGEMINI-3inthepresenceofmetalobjectslikescars,metalwalls,roofsorheavymetalreinforcementsinanystructure.Theirpresencewillmakeproperbalancingimpossible.

3.Picktheunitupbythehandleandbalanceitsothatit is levelwith theground andatnormalcarryingheight (arm’s length).Fivecmhigher in the front isOK.Foradeepersearch,attachthefullylengthenedcarryingstraptotheeyeletsattheendsofthehandle(see illustrationonpage9).Youwill need toholdtheinstrumentatthislowerlevelwhiletuningifyouplantouse it lowered.Onsomehighlymineralizedgroundandsomeasphalt,youmaynotbeabletouseitwiththestrapfullylengthened.Youwillknowthisduringtuningifyoucannotreachasilence(null).Notreachinganullcanalsoindicatethepresenceofnearbymetal.Ifthisisthecase,moveawayfromthemetaltobalanceyourGEMINI-3tothegroundonly.

4.StillholdingtheGEMINI-3paralleltotheground,slowlyturn theBALANCEknob(witharrow)on the three-piecehandlecounterclockwiseuntilyougetsilence(null) and zero meter reading. At this point thereshouldbenosoundasyourotatetheknob1/8-to1/4-turn furthercounterclockwisebefore reachingsoundandmeterreadingagain.

5.Ifyoucannotnulltheaudiooryournullpointislessthan1/8turn,reduceSENSITIVITYslightlyandtryagain.

6.IfyoucanturntheBALANCEknobmorethan1/4turnwithoutanincreaseinthesoundormeter,increaseSENSITIVITYslightlyandtryagain.Keepadjustingasdescribeduntil1/4turnofsilence(null)isachieved.

SEARCHING

16

Tuning1.Setthetransmitter:

Power:ON2.Setthereceiver:

Power:ONSensitivity:ZERO

3.Slowly increase the SENSITIVITY control until theaudiosignalisheard,thenreduceSENSITIVITYuntiltheaudiojustdisappears.Thisisthepointatwhichaircouplinghasbeeneliminated.

Operating1.Locate theburiedpipebycircling thecontact

point, keeping the receiver in line with thecontactatalltimes.Stayatleast30feetfromthetransmitter.

2.Once the pipe has been located by a sharpincreaseinaudioandmetersignals,thepipemaybetracedexactlyasdescribedintheoperatingsectionoftheInductivetraceinstructions.

3.BeawarethatanonconductivegasketinthepipewillterminatetheRFsignalfromthetransmitter.

TRACING

Figure 9.ConductiveTrace

10

SEARCHING

7.YouarereadytosearchwhentheBALANCEknobisadjustedwithin the1/8- to1/4-turn silence (null)space.Thisisextremelyimportant!Ifthisprocedureis not followed correctly, the GEMINI-3 will eitherconstantly give false audio and meter readings(sensitivity toohigh),orno signalsatall (sensitivitytoolow).ThesensitivitywillbecorrectlysetandyourGEMINI-3willoperateproperlyonlywhena1/4-to1/8-turnnullhasbeenachieved.IfyoulowerorraiseyourGEMINI-3,youmayhavetoretunebymakingrepeatedadjustmentstotheBALANCEknoband/ortheSENSITIVITYcontrol.

Operating1.TestyourGEMINI-3inanareayouarereasonablysure

is freeof largeburiedobjects.Scatter somemetalobjects,suchasatoolbox,pieceofpipe.

2.Withtheinstrumentproperlytunedandheldinthehandorsuspendedbythestrap,slowlywalkdirectlytowardyour testobject.Keep thehandleas levelandsteadyaspossiblewhileinmotionorthetuningmaychangeandyou’llreceivefalsesignalsand/orlosesensitivity.

3.As you approach your target, the speaker soundandmeter indicationwill increase. Theywill reachmaximumreadingswhenyouaredirectlyovertheconductor (target). Remember, on the GEMINI-3;unlikeearliermodels, the soundvolumeandpitchcontinuetoincreaseafterthemeterpegs.Thisallowsyou topinpointwithoutconstantly readjusting theSENSITIVITYknob.

4.Asyoucrossthetarget,thesignalindicationswillbegintodecreasebecauseyouaremovingaway.Togetaprecisefixonthelocation,makeamarkatyourfeetwhenreadingsreachtheirmaximum.Crossoverthetarget,turnaroundandcomeback.Makeasecondmarkwhenreadingsreturntomaximum.Yourtargetwillbecenteredbetweenthetwomarks.

15

TRACING

Operating1. Oncethetwostartingpointshavebeenestablished

andthereceivertuned,walkawayfromthetransmitterintheassumeddirectionoftheburiedconductor.

2. Holdthereceiververticallytomaintainapeaksignalorhorizontally,faceup,tomaintainanullorminimumsignal.Eithermethodindicatesthatyouareovertheobjectandtracingitspath.

3.As thedistance from the transmitter increases, thesignalwillfade.Asthisoccurs,increasetheSENSITIVITYasrequired.

4. Whenthesignalbecomestooweaktotrace,stopandmovethetransmittercloser.

5. Beawarethatifyouaretracingapipe,eachtimea“T”junctionorlateralisencountered;thesignalwillsplitandweaken.

Conductive Trace Thisisthebestmethodfortracingasinglepipeinthepresenceofotherpipes.Aportionofthepipemustbeexposedinordertoenergizeitbydirectconnectionutilizing the optional Ground Plate Assembly orGroundRodAssembly.

Set Up1. Ifpossible,cleanthecontactpointofthepipewith

awirebrush.2. Connectthegroundplateclamptothecontactpoint.3. Plug the Ground Plate Assembly or Ground Rod

AssemblyintothetransmitterGroundPlateJack.4. Setthetransmitteronthegroundandinanupright

position as far away from the contact point aspossible,atrightanglestotheassumeddirectionofthepipeorcable.InserttheGroundPlateorGroundRodAssembly in thegroundas faraway fromthetransmitteraspossible.LaytheGroundPlateflatonpavedsurfaces.Placingitinapuddleofwaterandweighingitwitharockwillhelpconductivity.

5. Holdthereceiververtically,inlinewiththecontactpointofthepipeatleast30feetaway.

11

SEARCHING

5.Forevenmoreaccuratepinpointingofshortobjects,(i.e.,apipe,cable,etc.)approachthetestobjectatrightanglesfromyourpreviousdirection.Markthegroundasyoudidbefore.Yourtestobjectshouldbeaboutcenteredbetweenfourmarks.

6. Toestablish thepathofapipe,cable,orother longconductor, pinpoint two more locations 15-20 feetapart.Fromthesethreelocationsyoushouldbeabletodrawastraightline(unlessthepipeisn’tstraight).Carefuladditionallocationsmaybenecessaryifnoprints(mapsofundergroundlines)oftheareaareavailable.

7. Itmaybenecessary to reduce sensitivitywith theSENSITIVITYknobwhenthepipeorcableislargeand/orshallow.Ifthemeterneedlehaspeakedandsoundisatahighlevel,youwillwanttobringthesensitivitydowntoseethepeakoftheneedleatapointlessthan100asyoumoveinhalforquarterstepsbackandforthtogetyourpeakreading.

8. If at all possible, practice over someburiedtargetsofknownsizeanddepth.

9. There are several things to considerwhenlocatingburiedobjects:a.Preciselocationdependsonoperatorskill.b. Position of the ground marks does not

indicatesizeoftheobjectoritspath.c.More thanonemetalobjectmaycause

a wider or stronger response thanexpected.

d.Deepertargetsmaynotproduceasignaluntiltheoperatorhaspasseddirectlyoverthem.

e.Reducing the receiverSENSITIVITYcontrolwillnarrowtheareabetweenthegroundmarksformoreprecisepinpointing.

f. Smallordeeplyburiedobjects suchasacache of coins, require a tight, closelytraversedsearchpattern.Largeorshallowobjectscanbe locatedsuccessfullywitha larger, more widely traversed searchpattern.

Figure 6. Handlestrap:Usingthehandlestrapincreasesdepth;however,itmaybedifficulttotunetheGEMINI-3thisclosetohighlymineralizedground.

14

TRACING

Inductive TraceTheInductiveTracemodeisusuallyusedtotracea longobject (pipe,orevein,etc.) that showsnoexposedportions,buttwostartingpointsareknown.

Set UpLocatetwopointsalongtheconductiveobjectatleast30 feetapartasdescribed in theWideScanor Narrow Scan Inductive Search sections. Thetransmitterandreceivershouldbeinlinewitheachother,bothfacingthesamedirection.Thetransmittershouldbeonthegroundandthereceivershouldbeheldbytheoperator.

Tuning1. Setthetransmitter:

Power:ON2. Setthereceiver:

Power:ONSensitivity:ZERO

3. Increase the receiver SENSITIVITY control until youhaveanaudio responseandat leastamid-scalemeterdeflection.

4. Determine thatyouarenotdirectaircouplingbymovingthereceiverbackandforth.Theaudiometerindications shouldpeakover theobject.Nopeakwillbeobserved if the receiver is tooclose to thetransmitteranddirectaircouplingisoccurring.

Figure 8. InductiveTrace

12

SEARCHING

Wide Scan Inductive Search Thismodeofoperationisthepreferredmethodforsearchinga largeareaquickly. Twooperatorsarerequiredandthehandleassemblyisnotused.

TheWideScanInductiveSearchmodeispracticalonlywhen searching fororeveins,pipesorcable40feetlongormore.Iftheoperatorsaretooclosetogether, “directaircoupling”will result,meaningthe receiver is detecting the Transmitter signaldirectlythroughtheairinsteadofthroughaburiedconductor.

Set Up Twooperatorslineupatleast20feetapart,onewiththereceiverandonewiththetransmitter,paralleltotheassumeddirectionoftheburiedconductor.Thetransmitterandreceivershouldbeinlinewitheachother,facingthesamedirection.

1.Setthetransmitter:Power:ON

2.Setthereceiver:Power:ONSensitivity:ZERO

Figure 7. WideScanInductiveSearch

Tuning

13

SEARCHING

3. SlowlyincreasetheSENSITIVITYcontroluntiltheaudiosignalisheard,thenreduceSENSITIVITYuntiltheaudiojustdisappears.Thisisthepointatwhich“aircoupling”hasbeeneliminated.

Operating

1. Keepingthereceiverandtransmittersectionsinline,thetwooperatorscannowwalktheirpredeterminedsearch pattern. The SENSITIVITY control should becheckedperiodicallytoensurethatthereceiver istunedjustbelowthe“aircoupling”threshold.

2. Ifbothoperatorscross thesameconductivebody(pipe,cable,orevein,etc.)atapproximately thesametime,thereceivertoneandmeterwill risetoindicateitspresence.Thereceiveroperatorshouldalertthetransmitteroperatorthattheyhavedetectedaconductiveobject.

3. The receiveroperator should thenholdhispositionwhilethetransmitteroperatormovesbackandforthfor the strongest receiver response. At this point,thetransmitteroperatorshouldstopandplacetheinstrumenton thegroundwith thehandlegripontop.

4.Thereceiveroperatorcanthenpinpointtheburiedobjectbymovingthereceiverbackandforthinlinewith the transmitter. Theobject shouldbedirectlybeneaththepointofmaximumresponse.

5. ThereceiveroperatormaythentracethesignalalongthelengthoftheunseenobjectasdescribedintheInductiveTracesection(page12).

12

SEARCHING

Wide Scan Inductive Search Thismodeofoperationisthepreferredmethodforsearchinga largeareaquickly. Twooperatorsarerequiredandthehandleassemblyisnotused.

TheWideScanInductiveSearchmodeispracticalonlywhen searching fororeveins,pipesorcable40feetlongormore.Iftheoperatorsaretooclosetogether, “directaircoupling”will result,meaningthe receiver is detecting the Transmitter signaldirectlythroughtheairinsteadofthroughaburiedconductor.

Set Up Twooperatorslineupatleast20feetapart,onewiththereceiverandonewiththetransmitter,paralleltotheassumeddirectionoftheburiedconductor.Thetransmitterandreceivershouldbeinlinewitheachother,facingthesamedirection.

1.Setthetransmitter:Power:ON

2.Setthereceiver:Power:ONSensitivity:ZERO

Figure 7. WideScanInductiveSearch

Tuning

13

SEARCHING

3. SlowlyincreasetheSENSITIVITYcontroluntiltheaudiosignalisheard,thenreduceSENSITIVITYuntiltheaudiojustdisappears.Thisisthepointatwhich“aircoupling”hasbeeneliminated.

Operating

1. Keepingthereceiverandtransmittersectionsinline,thetwooperatorscannowwalktheirpredeterminedsearch pattern. The SENSITIVITY control should becheckedperiodicallytoensurethatthereceiver istunedjustbelowthe“aircoupling”threshold.

2. Ifbothoperatorscross thesameconductivebody(pipe,cable,orevein,etc.)atapproximately thesametime,thereceivertoneandmeterwill risetoindicateitspresence.Thereceiveroperatorshouldalertthetransmitteroperatorthattheyhavedetectedaconductiveobject.

3. The receiveroperator should thenholdhispositionwhilethetransmitteroperatormovesbackandforthfor the strongest receiver response. At this point,thetransmitteroperatorshouldstopandplacetheinstrumenton thegroundwith thehandlegripontop.

4.Thereceiveroperatorcanthenpinpointtheburiedobjectbymovingthereceiverbackandforthinlinewith the transmitter. Theobject shouldbedirectlybeneaththepointofmaximumresponse.

5. ThereceiveroperatormaythentracethesignalalongthelengthoftheunseenobjectasdescribedintheInductiveTracesection(page14).

11

SEARCHING

5.Forevenmoreaccuratepinpointingofshortobjects,(i.e.,apipe,cable,etc.)approachthetestobjectatrightanglesfromyourpreviousdirection.Markthegroundasyoudidbefore.Yourtestobjectshouldbeaboutcenteredbetweenfourmarks.

6. Toestablish thepathofapipe,cable,orother longconductor, pinpoint two more locations 15-20 feetapart.Fromthesethreelocationsyoushouldbeabletodrawastraightline(unlessthepipeisn’tstraight).Carefuladditionallocationsmaybenecessaryifnoprints(mapsofundergroundlines)oftheareaareavailable.

7. Itmaybenecessary to reduce sensitivitywith theSENSITIVITYknobwhenthepipeorcableislargeand/orshallow.Ifthemeterneedlehaspeakedandsoundisatahighlevel,youwillwanttobringthesensitivitydowntoseethepeakoftheneedleatapointlessthan100asyoumoveinhalforquarterstepsbackandforthtogetyourpeakreading.

8. If at all possible, practice over someburiedtargetsofknownsizeanddepth.

9. There are several things to considerwhenlocatingburiedobjects:a.Preciselocationdependsonoperatorskill.b. Position of the ground marks does not

indicatesizeoftheobjectoritspath.c.More thanonemetalobjectmaycause

a wider or stronger response thanexpected.

d.Deepertargetsmaynotproduceasignaluntiltheoperatorhaspasseddirectlyoverthem.

e.Reducing the receiverSENSITIVITYcontrolwillnarrowtheareabetweenthegroundmarksformoreprecisepinpointing.

f. Smallordeeplyburiedobjects suchasacache of coins, require a tight, closelytraversedsearchpattern.Largeorshallowobjectscanbe locatedsuccessfullywitha larger, more widely traversed searchpattern.

Figure 6. Handlestrap:Usingthehandlestrapincreasesdepth;however,itmaybedifficulttotunetheGEMINI-3thisclosetohighlymineralizedground.

14

TRACING

Inductive TraceTheInductiveTracemodeisusuallyusedtotracea longobject (pipe,orevein,etc.) that showsnoexposedportions,buttwostartingpointsareknown.

Set UpLocatetwopointsalongtheconductiveobjectatleast30 feetapartasdescribed in theWideScanor Narrow Scan Inductive Search sections. Thetransmitterandreceivershouldbeinlinewitheachother,bothfacingthesamedirection.Thetransmittershouldbeonthegroundandthereceivershouldbeheldbytheoperator.

Tuning1. Setthetransmitter:

Power:ON2. Setthereceiver:

Power:ONSensitivity:ZERO

3. Increase the receiver SENSITIVITY control until youhaveanaudio responseandat leastamid-scalemeterdeflection.

4. Determine thatyouarenotdirectaircouplingbymovingthereceiverbackandforth.Theaudiometerindications shouldpeakover theobject.Nopeakwillbeobserved if the receiver is tooclose to thetransmitteranddirectaircouplingisoccurring.

Figure 8. InductiveTrace

10

SEARCHING

7.YouarereadytosearchwhentheBALANCEknobisadjustedwithin the1/8- to1/4-turn silence (null)space.Thisisextremelyimportant!Ifthisprocedureis not followed correctly, the GEMINI-3 will eitherconstantly give false audio and meter readings(sensitivity toohigh),orno signalsatall (sensitivitytoolow).ThesensitivitywillbecorrectlysetandyourGEMINI-3willoperateproperlyonlywhena1/4-to1/8-turnnullhasbeenachieved.IfyoulowerorraiseyourGEMINI-3,youmayhavetoretunebymakingrepeatedadjustmentstotheBALANCEknoband/ortheSENSITIVITYcontrol.

Operating1.TestyourGEMINI-3inanareayouarereasonablysure

is freeof largeburiedobjects.Scatter somemetalobjects,suchasatoolbox,pieceofpipe.

2.Withtheinstrumentproperlytunedandheldinthehandorsuspendedbythestrap,slowlywalkdirectlytowardyour testobject.Keep thehandleas levelandsteadyaspossiblewhileinmotionorthetuningmaychangeandyou’llreceivefalsesignalsand/orlosesensitivity.

3.As you approach your target, the speaker soundandmeter indicationwill increase. Theywill reachmaximumreadingswhenyouaredirectlyovertheconductor (target). Remember, on the GEMINI-3,unlikeearliermodels, the soundvolumeandpitchcontinuetoincreaseafterthemeterpegs.Thisallowsyou topinpointwithoutconstantly readjusting theSENSITIVITYknob.

4.Asyoucrossthetarget,thesignalindicationswillbegintodecreasebecauseyouaremovingaway.Togetaprecisefixonthelocation,makeamarkatyourfeetwhenreadingsreachtheirmaximum.Crossoverthetarget,turnaroundandcomeback.Makeasecondmarkwhenreadingsreturntomaximum.Yourtargetwillbecenteredbetweenthetwomarks.

15

TRACING

Operating1. Oncethetwostartingpointshavebeenestablished

andthereceivertuned,walkawayfromthetransmitterintheassumeddirectionoftheburiedconductor.

2. Holdthereceiververticallytomaintainapeaksignalorhorizontally,faceup,tomaintainanullorminimumsignal.Eithermethodindicatesthatyouareovertheobjectandtracingitspath.

3.As thedistance from the transmitter increases, thesignalwillfade.Asthisoccurs,increasetheSENSITIVITYasrequired.

4. Whenthesignalbecomestooweaktotrace,stopandmovethetransmittercloser.

5. Beawarethatifyouaretracingapipe,eachtimea“T”junctionorlateralisencountered;thesignalwillsplitandweaken.

Conductive Trace Thisisthebestmethodfortracingasinglepipeinthepresenceofotherpipes.AportionofthepipemustbeexposedinordertoenergizeitbydirectconnectionutilizingaGroundRodAssembly(notincluded).

Set Up1. Ifpossible,cleanthecontactpointofthepipewith

awirebrush.2. Connectthegroundplateclamptothecontactpoint.3. Plug a Ground Rod Assembly into the transmitter

GroundPlateJack.4. Setthetransmitteronthegroundandinanupright

position as far away from the contact point aspossible,atrightanglestotheassumeddirectionofthepipeorcable.InsertaGroundRodAssemblyinthegroundasfarawayfromthetransmitteraspossible.

5. Holdthereceiververtically,inlinewiththecontactpointofthepipeatleast30feetaway.

9

Tuning1.Setthetransmitter: Power:ON

2.SettheReceiver: Power:ON Sensitivity:7 You should get a strong audio tone and meter

indicationatthispoint.CAUTION:NeverattempttotunetheGEMINI-3inthepresenceofmetalobjectslikescars,metalwalls,roofsorheavymetalreinforcementsinanystructure.Theirpresencewillmakeproperbalancingimpossible.

3.Picktheunitupbythehandleandbalanceitsothatit is levelwith theground andatnormalcarryingheight (arm’s length).Fivecmhigher in the front isOK.Foradeepersearch,attachthefullylengthenedcarryingstraptotheeyeletsattheendsofthehandle(see illustrationonpage9).Youwill need toholdtheinstrumentatthislowerlevelwhiletuningifyouplantouse it lowered.Onsomehighlymineralizedgroundandsomeasphalt,youmaynotbeabletouseitwiththestrapfullylengthened.Youwillknowthisduringtuningifyoucannotreachasilence(null).Notreachinganullcanalsoindicatethepresenceofnearbymetal.Ifthisisthecase,moveawayfromthemetaltobalanceyourGEMINI-3tothegroundonly.

4.StillholdingtheGEMINI-3paralleltotheground,slowlyturn theBALANCEknob(witharrow)on the three-piecehandlecounterclockwiseuntilyougetsilence(null) and zero meter reading. At this point thereshouldbenosoundasyourotatetheknob1/8-to1/4-turn furthercounterclockwisebefore reachingsoundandmeterreadingagain.

5.Ifyoucannotnulltheaudiooryournullpointislessthan1/8turn,reduceSENSITIVITYslightlyandtryagain.

6.IfyoucanturntheBALANCEknobmorethan1/4turnwithoutanincreaseinthesoundormeter,increaseSENSITIVITYslightlyandtryagain.Keepadjustingasdescribeduntil1/4turnofsilence(null)isachieved.

SEARCHING

16

Tuning1.Setthetransmitter:

Power:ON2.Setthereceiver:

Power:ONSensitivity:ZERO

3.Slowly increase the SENSITIVITY control until theaudiosignalisheard,thenreduceSENSITIVITYuntiltheaudiojustdisappears.Thisisthepointatwhichaircouplinghasbeeneliminated.

Operating1.Locate theburiedpipebycircling thecontact

point, keeping the receiver in line with thecontactatalltimes.Stayatleast30feetfromthetransmitter.

2.Once the pipe has been located by a sharpincreaseinaudioandmetersignals,thepipemaybetracedexactlyasdescribedintheoperatingsectionoftheInductivetraceinstructions.

3.BeawarethatanonconductivegasketinthepipewillterminatetheRFsignalfromthetransmitter.

TRACING

Figure 9.ConductiveTrace

8

SEARCHING

Narrow Scan Inductive Search Thismodeofoperationisperformedbyasingleoperatorusingthe3-piecehandle.Itisthebestmethodforlocatingsmallorshortobjects(chest,coin-jar,rifle,etc.).However,itisalsoaneffectivewaytolocatepipes,cablesandoreveins.Set Up

1. Assemblethe3-piecehandlebyinsertingeachendpieceintothecenterhandlesection.Tightenthetwocenterknobsfingertightuntilthereisnowobble.PlacethetransmitteronitsbackandinserttheendofthehandlewiththesinglebrassshaftintotheV-shapedslot.Turntheknobuntilitisfingertightandthehandleisfirmlyintheslot.

2.Alignthereceiverpanelholeswiththeupper-handlethreadedshafts.Tightenthelowerblackknobuntilitisfingertight.

3.Turnthebalanceknob(withwhitearrow)untilthespringisundertension(atleast10turns).

Figure 4.NarrowScanInductiveSearch

Figure 5.AssemblyforNarrowScanInductiveSearch

17

PROSPECTING TIPSMapping

Whenanareaofhighconductivityisencountered,outline and stake it by crossing and re-crossing,using theNarrowScan Inductive Searchmode. Itwillbenotedthatinandneartheconductivezone,amaximumindicationwillbereceivedinonlyonedefinitedirectionwhentheoperatorstandsatonepointandrotatestheinstrumentparalleltothesurfaceoftheground.Recordthemeterreadingsasreadin themaximumdirections,atvariouspointsalongthe zones.Note thecharacterof theoverburden,outcropsandtopographicfeatures. Whentheareabeinginductivelysurveyedhasbeencompletelycoveredandalloftheconductivezoneshavebeen staked, these zonesare surveyedandplottedonamap.Themapshouldincludeallcreekbottoms,gullies,outcropsandotherphysicalfeatures.Theidealmaponwhichtoplottheconductivezonesisatopographicandgeologicalmapoftheproperscale.Inthiswayitispossibletocorrelatethezonesdirectlywiththetopographyandgeology,andthusdeterminethepossiblereasonsforthepresenceofthevariousconductivezones.

Locating Placer Deposits Alotofprospectorshavetoldustheywouldliketouseatwo-boxforlocatingplacergold.Ingeneral,thesedepositscontainsuchasmallamountofgoldthat itcannotbedetected.Placergold,however,isusuallyassociatedwithacertainamountofblacksand,andsomeplacerdepositscarryironsulphide.Both of these mineral substances are definitelyconductive,andmaybedetectedbytheGEMINI-3.Itisthroughthedetectionofthesemineralsthattheplacergoldmaybelocated.

RECEIVER

Speaker: Provides audible indication of the receiver signal for

balancinganddetecting.

Meter:ProvidesvisualindicationoftheReceiversignalresponsefor

balancinganddetecting.Alsousedasabatterytestindicator.

Sensitivity Control:Usedtocontrolsensitivitylevel.Thecircled“7”

indicatesthestartinglevelusedforNarrowScanInductiveSearch

Mode.

Headphone Jack:Acceptsstereoormonauralheadphonesand

silencesspeakerwhenheadphonesarepluggedin.(Stereo/mono

headphonesshouldbein“stereo”position.)

Power Switch: Pullingswitchoutturnsonreceiver.

Meter

SensitivityControl

HeadphoneJack

PowerSwitch

Speaker

Figure 3.Receiver

BatteryTestSwitch

718

PROSPECTING TIPS

Sources of Error The most common nonproductive zones ofconductivityare:

1. Dissolved mineral salts - Mineral salts becomeconductivewhendissolvedinwater.Asaresult,thepresenceofsalinewaterorwatersaturatedsoilhighinsaltcontentmayrendertheGEMINI-3useless.

2.Rough terrain-Inveryroughterrainitmaybedifficultto maintain the GEMINI-3 parallel to the ground,resultinginfrequentfalsesignals.

3. Irregularities in the overburden bedrock -TheGEMINI-3maydetectsharpchangesinconductivitywhichareofnoimportantgeologicalsignificance.

4. Fault zones -Faultzonesoftengivepositiveindicationsbecausetheyarehighlyfracturedandusuallycontainconcentrationsofwaterandminerals.

5. Alluvial deposits along creek bottoms - Conductivedepositsalongcreekbedsusuallyhavenoeconomicvalueorimportanceindeterminingthegeology.

6. Conductive debris -Unexpectedhighreadingsareoften due to highly conductive debris near thesurfacesuchasscrapiron,tincans,etc.

7. Magnetite - Heavyconcentrationsofmagnetitewillcausefalsesignalsand/orlossofpenetratingpower.

It isobvious fromtheabovethatevery responseby the GEMINI-3 does not indicate the presenceofvaluableore,but ratheran indication that theearth’sconductivityhaschanged.Itremainsfortheoperatortoproperlyinterpretthisdata.Thesuccessfulprospectorwillhavesomeunderstandingoftheoreheisseekingandoftheexistinggeologicalconditions.The successfuloperatorwillalsohavestudied thatareaandwillknowinadvancewhatoreheisseekingandwherethebestopportunityexistsforlocatingit.Under theseconditions, theGEMINI-3canprovidevaluable information.On theotherhand, randomwanderingandprospectingforno inparticularcanbeanexpensivewasteoftime.

one

TRANSMITTER

BatteryLevelMeter

PowerSwitch GroundPlateJack

Figure 2. Transmitter

Power Switch: Pulloutswitchturnsonpower.

Ground Plate Jack:UsedwiththeoptionalGroundPlateAssembly

fortheConductiveTraceMode.

Battery Level Meter:Givesavisualindicationofbatterystrength.

Replacebatteriesifbelow5onmeter.

6 19

BATTERY REPLACEMENT1. Turneitherinstrument(TransmitterandReceiver)over

onitsfaceandremoveaccessplatewithcoinorlargebladescrewdriver.

2. Lift thebatterypackoutcarefully.Turnthebatterypackslightly,unsnapthebatteryconnectorandslipoff the sleeve.Changealleightbatteries. Slip thesleevebackon,thenreattachtheconnectortothepack.Slipthebatterypackbackintoitscompartmentanddoabattery test.Refasten theaccessplate.Boththetransmitterandreceiverwillworkfrom30to40hoursonasetof8standardquality,carbon-zincbatteries. Alkaline batteries will give substantiallylonger lifeand incoldweatherwillperformmuchbetterthanstandardcarbonzinc

ChangingBatteries

batteries.

NOTE: As supplied from the factory, the battery pack is surrounded by a plastic sleeve to retain the batteries during possible rough handling and shipping. As a precaution, always reinstall the sleeve after battery replacement.

DO NOT MIX OLD AND NEW BATTERIES

Figure 10.

5

DEPTH TheGEMINI-3wasdesignedtolocatelarge,deepobjectssuchasanironchest,pipeoranorevein.Itwillnotdetectsmallcoin-sizedobjects.Aquartjarfullofcoins,however,maybedetectedone-to-threefeetdeep.A55-gallondrummaybedetectedasdeepas10feet.Averylargeobject,likeanautomobile,maybedetectedat20feetormore. TheabilityoftheGEMINI-3todetectobjectsatvariousdepthsdependsonseveralfactors:

1. Ground Mineralization:ThepenetratingpoweroftheGEMINI-3isadverselyaffectedbythepresenceofmagnetite(ablackironoxide)andwetconductivemineralsalts.Forexample,anobjectthatcanbedetected at 15 feet in neutral ground may bedetectednodeeperthan5feetinhighlymineralizedground.

2. Size and Depth of Object:A4-inchdiametertargetwillproducesignal64timesstrongerthanasimilar1-inchdiametertargetatthesamedepth.Anobject1-footundergroundwillproduceasignal4,000timesgreaterthantheobject4feetdeep.

3. Length of Time Object is Buried:Anobjectthathasbeenburiedforalongtimemaybeeasiertodetectthananewlyburiedobject.Rustandotheroxidesaswellasmineralizationcausedbytheinteractionofthemetalwithsoilchemicalsaregoodconductorsandaiddetection.

4. Shape of an Object:Ringorloopedshapedobjectslyingflatproducethebestresults.Flatordishshapedtargetsarealsoeasytodetect.Rodshapedobjects,especiallywhenscannedonend,areverydifficulttodetect.

5. Operator Skill:Probablythemostimportantfactorof

all,practiceoverknownburiedtargetsisessential.

20

LET’S PRESERVE OUR TREASURED SPORT!

Lawsgoverningtheuseofmetaldetectorsarecommoninsomeareas.Inmanycountries,theuseofmetaldetectorsisillegalorseverelyrestricted.DON’TLETTHISHAPPENINYOURCOUNTRY!

•AlwayscheckFederal,State,Countyandlocallawsbeforesearching.

•Respectprivatepropertyanddonotenterprivatepropertywithouttheowner’spermission.

•Takecaretorefillallholesandleavenodamage.•Removeanddisposeofanyandalltrashandlitterfound.•Appreciateandprotectourinheritanceofnaturalresources,

wildlifeandprivateproperty.•Actasanambassadorforthehobby,usethoughtfulness,

considerationandcourtesyatalltimes.•Neverdestroyhistoricalorarchaeologicaltreasures.•All treasurehuntersmaybe judgedby theexampleyouset;

always conduct yourself with courtesy and consideration ofothers.

TREASURE HUNTERS’ CODE OF ETHICS

4

BASIC THEORY OF OPERATION The GEMINI-3 was engineered to detect conductivitychangesintheearthoverwhichitiscarried.Hence,apositiveresponsebytheGEMINI-3indicatesthepresenceofametalobject,oreveinormineralthatismoreconductivethanthesurroundingrockorsoil.

ThefunctionoftheGEMINI-3Transmitteristosendaradiofrequency (RF) signal down to a conductive object andgenerate an electromagnetic field around that object.When used in any of the Inductive modes, the RF signaltravels through the ground to the object. When used inthe Conductive Trace mode (see page 13), the signal istransmitteddirectlythroughawireattachedtoanexposedportionoftheobject.

The function of the GEMINI-3 Receiver is to locate theobjectbydetectingtheelectromagneticfieldarounditandrespondingwithaudioandvisualsignals.

21

National Forest and Federal Lands—Metaldetectingisallowedonlybyspecialpermitacquiredfromthefederalgovernment.Eachareahasadistrictoffice.

Corps of Engineers, Lakes, Shorelines and Lands—Permissionhasbeengrantedonlyonpre-disturbedsites,suchasbeachesandattachedswimmingareas.NewCorpslakesandlandsmustbeokayedbythemainofficeoftheArmyCorpsofEngineers.Eachareahasadistrictoffice.

State Parks and Lands—Somestateparksareopentometaldetecting,butsomearenot.Alwayscheckwiththeparkrangerbeforeattemptingtouseyourdetector.

Bureau of Land Management (BLM) Lands—Someareasareopenformetaldetecting,andsomearenot.Alwayscheckwiththedistrictoffice.

City or County Park Lands—Mostareopentometaldetectingunlessnoticeisgivenbyasignorcityordinance.Whenindoubt,alwayscheckwiththecity’sParksandRecreationDepartment.PublicSchoolGrounds—Mostareopentometaldetectingunlessnoticeisgivenbyasign,cityordinance,lawenforcementofficial,orschoolemployee.Youshouldalwayscheckwiththeschoolofficefirst.

Privately Owned Lands (Private Property)—Permissionrequired.Itisalwaysbesttohavethepermissioninwriting.

Historically Marked Lands or Sites—Metaldetectingisnotallowed.Don’teventhinkaboutit.

Where To Use Your Metal Detector In The U.S.

3

ABOUT YOUR DETECTORTwo-box metal detectors have long been used by

prospectors, geologists, treasure hunters and public utilitycompanies to locate large,deepobjects,orevein,pipesandcables. FisherResearchLaboratory is the recognizedleaderinthefield,infact,theyweregrantedthefirsttwo-boxmetaldetectorpatentover60yearsago.

Youmightthinkitwouldbedifficulttoimproveonaproductthathasbeeninaconstantstateofdevelopmentforsomanyyears.Butthefactis,theGEMINI-3isprobablythebiggestleapforwardintwo-boxdesignsinceit replacedvacuumtubeswithtransistorsbackinthe1950s.

ThenewGEMINI-3goes10to20percentdeeperthanitspredecessor.Itwilltracemostpipesandoreveinsatleast50percentfarther,andthenewcrystalcontrolledcircuitryis rock stable. The old metal-rim antenna is gone and soarethehard-to-getbatteries.TheGEMINI-3iseasiertouse,twopoundslighter,&featuresVoltageControlledOscillator(VCO),audiotargetresponseforprecisionpinpointing.

YourFisherGEMINI-3isahighquality,precisioninstrumentengineered by the oldest and proudest name in metaldetectors.Treatitright,readthisinstructionmanualthoroughlyandpracticeoften.Whoknows,withskill,patienceandalittleluck,youmayfindtheBIGONE.

Drop us a line if you have any questions, comments orexcitingGEMINI-3stories.Inthemeantime...

Happyhunting,FISHERRESEARCHLABORATORY

22

SPECIFICATIONSDimensions

Lengthonhandle............................................................491/2inchesTransmitter-ReceiverBoxAssembly.................................................91/4x12x6inches(23.5x30x15cm)

Weight Complete...........................................................................7lbs.(3.2k)Transmitter........................................................................2.4lbs.(1.1k)Receiver...........................................................................2.9lbs.(1.3k)Handle..............................................................................1.7lbs.(.75k)

FrequencyRFSearchandTrace............................81.92KHzCrystalControlled.................................................AudioTargetResponse(V.C.O.)

Operating Modes Search 1.NarrowScan,Inductive 2.WideScan,InductiveTrace 1.Inductive 2.Conductive

Target ResponseMeter...................................................... 21/4x13/4inches,AnalogSpeaker............................................................21/4inches,100ohm,MoistureProofConeHeadphones.......................................... 1/4inchJack,8-16ohms,

............................................................................................Stereo/Mono

Batteries Receiver.............................................................................. (8)AA1.5VTransmitter.......................................................................... (8)AA1.5VLife...........................................CarbonZinc............................ 30Hours

.................................................Alkaline.................................... 50Hours

2

3

4

5

2 6

2

CONTENTSAbout Your Gemini-3 ............................................................... pg. 3Basic Theory of Operation ....................................................... pg. 4Depth pg. 5Transmitter .................................................................................pg. 6Receiver ....................................................................................pg. 7Searching ..................................................................................pg. 8 Narrow Scan Inductive Search ........................................... pg. 8 Set Up .............................................................................pg. 8 Tuning .............................................................................pg. 9 Operation ...................................................................... pg. 10 Wide Scan Inductive Search ............................................... pg. 12 Set Up .............................................................................pg. 12 Tuning .............................................................................pg. 12 Operation ...................................................................... pg. 13Tracing .......................................................................................pg. 14 Inductive Tracing.................................................................. pg. 14 Set Up .............................................................................pg. 14 Tuning .............................................................................pg. 14 Operation ...................................................................... pg. 15 Conductive Trace ................................................................ pg. 15 Set Up .............................................................................pg. 15 Tuning .............................................................................pg. 16 Operation ...................................................................... pg. 16Prospecting Tips ........................................................................ pg. 17 Mapping ................................................................................pg. 17 Locating Placer Deposits ..................................................... pg. 17 Sources of Error ..................................................................... pg. 18Battery Replacement ............................................................... pg. 19Treasure Hunters’ Code Of Ethics ............................................ pg. 20Where To Use Your Metal Detector In The U.S. ...................... pg. 21Specifications ...........................................................................pg. 22Using Headphones ................................................................... pg. 23

23

Notes

1. Subjecttoimprovementormodificationwithoutnotice.2. Approximate.3. VoltageControlledOscillator.Volumeandpitchbothincreaseastargetisapproachedforeasier,moreaccuratepinpointing.4. Withoptionalgroundplateassembly.5. Optionalstereo/monoheadphones.6. Useofheadphoneswillsignificantlyincreasebatterylife.

FisherResearchLaboratorydoesnotwarrantsuitabilitytospecificuse.FisherResearchLaboratoryshallinnoeventbeliable for any direct, incidental, consequential or indirectdamages.

SPECIFICATIONS

Usingheadphones(notincluded)improvesbatterylife,andpreventsthesoundsfromannoyingbystanders.Italsoallowsyoutohearsubtlechangesinthesoundmoreclearly,particularlyifsearchinginanoisylocation.Forsafetyreasons,donotuseheadphonesneartrafficorwhereotherdangersarepresent.Thisdeviceistobeusedwithinterconnectingcables/headphonecablesshorterthanthreemeters.

USING HEADPHONES

Gemini-3

Operating Manual

2-Box Metal and Mineral Detectorfor Deep Search and Cache Locating

8703520000 Rev.3 072414

Q U A L I T YFisherdetectorsarerenownedfortheirquality.

EachdetectorishandcraftedintheUSAwithpride

P E R F O R M A N C ETheworldwideundergroundutilityindustryreliesonFisher®.

Ourinstrumentsaredurable,dependable,andlocatedeeper.

R E P U T A T I O NFisherproducedthefirstpatentedmetaldetectorin1931.Forover80years,theFisherlogohasbeenamarkofexcellence.

5 - YEAR LIMITED WARRANTYRegister your warranty on-line for a chance to win a

FREE DETECTOR.For details, visit www.fisherlab.com

Fisher®believesintheproductsweproduceandbacksthisbeliefwitha5yearlimitedwarranty.

Proof of purchase is required to make a claim under this warranty.

NOTE TO CUSTOMERS OUTSIDE THE U.S.A.Thiswarrantymayvaryinothercountries,checkwithyour

distributorfordetails.Warrantydoesnotcovershippingcosts.

S E R V I C EFisheriscommittedtoprovidingyou,ourvaluedcustomer,withsuperiorservice.Eachandeveryinstrumentisrigidlytestedand

carefullyinspectedduringassemblyandbeforeshipment.

FISHER RESEARCH LABORATORY1465HenryBrennan,ElPaso,Texas79936

Tel915.225.0333Fax915.225.0336www.fisherlab.comemail:info@fisherlab.com

AccordingtoFCCpart15.21ChangesorModificationsmadetothisdevicenotexpresslyapprovedbythepartyresponsibleforcompliancecouldvoid

theuser’sauthoritytooperatethisequipment.