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SPECIFICATIONS

Dimensions

Length on handle ............................................................49 1/2 inches 
Transmitter-Receiver Box Assembly
.................................................9 1/4 x 12 x 6 inches(23.5 x 30 x 15 cm) 

Weight 

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

Frequency

RF Search and Trace  ............................81.92 KHz Crystal Controlled 

.................................................         

Audio Target Response (VCO) 

Operating Modes 

Search
  1. Narrow Scan, Inductive 
  2. Wide Scan, Inductive 
Trace
  1. Inductive 
  2. Conductive 

Target Response

 

Meter  ...................................................... 2 1/4 x 1 3/4 inches, Analog 
Speaker  ............................................................2 1/4 inches, 100 ohm, 
Moisture Proof Cone 
Headphones     .......................................... 1/4 inch Jack, 8-16 ohms,
............................................................................................Stereo/Mono 

Batteries 

Receiver ..............................................................................  (8) AA 1.5V 
Transmitter  ..........................................................................  (8) AA 1.5V 
Life ...........................................Carbon Zinc  ............................ 30 Hours 
.................................................Alkaline  .................................... 50 Hours 

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6

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ABOUT YOUR DETECTOR

Two-box  metal  detectors  have  long  been  used  by 

prospectors,  geologists,  treasure  hunters  and  public  utility 
companies to locate large, deep objects, ore vein, pipes 
and  cables.  Fisher  Research  Laboratory  is  the  recognized 
leader in the field, in fact, they were granted the first two-box 
metal detector patent over 60 years ago. 

You might think it would be difficult to improve on a product 

that has been in a constant state of development for so many 
years. But the fact is, the GEMINI-3 is probably the biggest 
leap forward in two-box design since it replaced vacuum 
tubes with transistors back in the 1950s. 

The new GEMINI-3 goes 10 to 20 percent deeper than its 

predecessor. It will trace most pipes and ore veins at least 
50 percent farther, and the new crystal controlled circuitry 
is  rock  stable.  The  old  metal-rim  antenna  is  gone  and  so 
are the hard-to-get batteries. The GEMINI-3 is easier to use, 
two pounds lighter, & features Voltage Controlled Oscillator 
(V.C.O.), audio target response for precision pinpointing.

Your Fisher GEMINI-3 is a high quality, precision instrument 

engineered  by  the  oldest  and  proudest  name  in  metal 
detectors. Treat it right, read this instruction manual thoroughly 
and practice often. Who knows, with skill, patience and a 
little luck, you may find the BIG ONE. 

Drop  us  a  line  if  you  have  any  questions,  comments  or 

exciting GEMINI-3 stories. In the meantime . . . 

Happy hunting, 
FISHER RESEARCH LABORATORY 

Summary of Contents for Gemini-3

Page 1: ...Gemini 3 Operating Manual 2 Box Metal and Mineral Detector for Deep Search and Cache Locating 1813...

Page 2: ...ing 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 16 Prospecting Tips pg 17 Mapping pg 17 Locating Placer Deposi...

Page 3: ...1950s The new GEMINI 3 goes 10 to 20 percent deeper than its predecessor It will trace most pipes and ore veins at least 50 percent farther and the new crystal controlled circuitry is rock stable The...

Page 4: ...uency RF signal down to a conductive object and generate an electromagnetic field around that object When used in any of the Inductive modes the RF signal travels through the ground to the object When...

Page 5: ...per than 5 feet in highly mineralized ground 2 Size and Depth of Object A 4 inch diameter target will produce signal 64 times stronger than a similar 1 inch diameter target at the same depth An object...

Page 6: ...e 2 Transmitter Power Switch Pull out switch turns on power Ground Plate Jack Used with the optional Ground Plate Assembly for the Conductive Trace Mode Battery Level Meter Gives a visual indication o...

Page 7: ...sensitivity level The circled 7 indicates the starting level used for Narrow Scan Inductive Search Mode Headphone Jack Accepts stereo or monaural headphones and silences speaker when headphones are p...

Page 8: ...Tighten the two center knobs finger tight until there is no wobble Place the transmitter on its back and insert the end of the handle with the single brass shaft into the V shaped slot Turn the knob...

Page 9: ...ome asphalt you may not be able to use it with the strap fully lengthened You will know this during tuning if you cannot reach a silence null Not reaching a null can also indicate the presence of near...

Page 10: ...ument properly tuned and held in the hand or suspended by the strap slowly walk directly toward your test object Keep the handle as level and steady as possible while in motion or the tuning may chang...

Page 11: ...han 100 as you move in half or quarter steps back and forth to get your peak reading 8 If at all possible practice over some buried targets of known size and depth 9 There are several things to consid...

Page 12: ...e together direct air coupling will result meaning the receiver is detecting the Transmitter signal directly through the air instead of through a buried conductor Set Up Two operators line up at least...

Page 13: ...ly the same time the receiver tone and meter will rise to indicate its presence The receiver operator should alert the transmitter operator that they have detected a conductive object 3 The receiver o...

Page 14: ...oth facing the same direction The transmitter should be on the ground and the receiver should be held by the operator Tuning 1 Set the transmitter Power ON 2 Set the receiver Power ON Sensitivity ZERO...

Page 15: ...pipe each time a T junction or lateral is encountered the signal will split and weaken Conductive Trace This is the best method for tracing a single pipe in the presence of other pipes A portion of t...

Page 16: ...rating 1 Locate the buried pipe by circling the contact point keeping the receiver in line with the contact at all times Stay at least 30 feet from the transmitter 2 Once the pipe has been located by...

Page 17: ...and plotted on a map The map should include all creek bottoms gullies outcrops and other physical features The ideal map on which to plot the conductive zones is a topographic and geological map of t...

Page 18: ...creek beds usually have no economic value or importance in determining the geology 6 Conductive debris Unexpected high readings are often due to highly conductive debris near the surface such as scra...

Page 19: ...s compartment and do a battery test Refasten the access plate Both the transmitter and receiver will work from 30 to 40 hours on a set of 8 standard quality carbon zinc batteries Alkaline batteries wi...

Page 20: ...ivate property without the owner s permission Take care to refill all holes and leave no damage Remove and dispose of any and all trash and litter found Appreciate and protect our inheritance of natur...

Page 21: ...to use your detector Bureau of Land Management BLM Lands Some areas are open for metal detecting and some are not Always check with the district office City or County Park Lands Most are open to meta...

Page 22: ...dle 1 7 lbs 75 k Frequency RF Search and Trace 81 92 KHz Crystal Controlled Audio Target Response V C O Operating Modes Search 1 Narrow Scan Inductive 2 Wide Scan Inductive Trace 1 Inductive 2 Conduct...

Page 23: ...oratory does not warrant suitability to specific use Fisher Research Laboratory shall in no event be liable for any direct incidental consequential or indirect damages SPECIFICATIONS Using headphones...

Page 24: ...this belief with a 5 year limited warranty Proof of purchase is required to make a claim under this warranty NOTE TO CUSTOMERS OUTSIDE THE U S A This warranty may vary in other countries check with yo...

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