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Q U A L I T Y
Fisher detectors are renowned for their quality.
Each detector is hand crafted in the USA with pride
P E R F O R M A N C E
The worldwide underground utility industry relies on Fisher
Our instruments are durable, dependable, and locate deeper.
R E P U T A T I O N
Fisher produced the first patented metal detector in 1931. For
over 80 years, the Fisher logo has been a mark of excellence.
5 - YEAR LIMITED WARRANTY
Register your warranty on-line for a chance to win a
FREE DETECTOR.
For details, visit www.fisherlab.com
Fisher
believes in the products we produce and backs 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 your
distributor for details.
Warranty does not cover shipping costs.
S E R V I C E
Fisher is committed to providing you, our valued customer, with
superior service. Each and every instrument is rigidly tested and
carefully inspected during assembly and before shipment.
According to FCC part 15.21 Changes or Modifications made to this device
not expressly approved by the party responsible for compliance could void
the user's authority to operate this equipment.
FISHER RESEARCH LABORATORY
1465 Henry Brennan, El Paso, Texas 79936
Tel 915.225.0333 Fax 915.225.0336
www.fisherlab.com email:info@fisherlab.com
8703520000
Rev.3
.
®
072414
Gemini-3
2-Box Metal and Mineral Detector
for Deep Search and Cache Locating
Operating Manual
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Table of Contents
Related Manuals for Fisher Gemini-3
Summary of Contents for Fisher Gemini-3
- Page 1 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 your distributor for details. Warranty does not cover shipping costs. S E R V I C E Fisher is committed to providing you, our valued customer, with superior service. Each and every instrument is rigidly tested and carefully inspected during assembly and before shipment. According to FCC part 15.21 Changes or Modifications made to this device not expressly approved by the party responsible for compliance could void the user’s authority to operate this equipment. FISHER RESEARCH LABORATORY 1465 Henry Brennan, El Paso, Texas 79936 Tel 915.225.0333 Fax 915.225.0336 www.fisherlab.com email:info@fisherlab.com Operating Manual 8703520000 Rev.3 072414...
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Page 2: Table Of Contents
CONTENTS SPECIFICATIONS About Your Gemini-3 ............... pg. 3 Notes Basic Theory of Operation ............pg. 4 Depth ..................pg. 5 1. Subject to improvement or modification without notice. Transmitter ................. pg. 6 2. Approximate. Receiver ..................pg. 7 3. Voltage Controlled Oscillator. Volume and pitch both increase as target is approached for easier, more Searching .................. pg. 8 accurate pinpointing. -
Page 3: About Your Gemini-3
Two-box metal detectors have long been used by Dimensions prospectors, geologists, treasure hunters and public utility Length on handle ............49 1/2 inches companies to locate large, deep objects, ore vein, pipes Transmitter-Receiver Box Assembly and cables. Fisher Research Laboratory is the recognized ..........9 1/4 x 12 x 6 inches(23.5 x 30 x 15 cm) leader in the field, in fact, they were granted the first two-box metal detector patent over 60 years ago. Weight Complete ................7 lbs. (3.2 k) Transmitter . -
Page 4: Basic Theory Of Operation
Conductive Trace mode (see page 15), the signal is open for metal detecting, and some are not. Always check with transmitted directly through a wire attached to an exposed the district office. portion of the object. City or County Park Lands—Most are open to metal detecting unless notice is given by a sign or city ordinance. When in doubt, always check with the city’s Parks and Recreation Department. The function of the GEMINI-3 Receiver is to locate the Public School Grounds—Most are open to metal detecting unless object by detecting the electromagnetic field around it and notice is given by a sign, city ordinance, law enforcement official, responding with audio and visual signals. or school employee. You should always check with the school office first. Privately Owned Lands (Private Property)—Permission required. It is always best to have the permission in writing. -
Page 5: Depth
TREASURE HUNTERS’ CODE OF ETHICS LET’S PRESERVE OUR TREASURED SPORT! The GEMINI-3 was designed to locate large, deep objects such as an iron chest, pipe or an ore vein. It will not detect small coin- sized objects. A quart jar full of coins, however, may be detected Laws governing the use of metal detectors are common in some one-to-three feet deep. A 55-gallon drum may be detected as areas. In many countries, the use of metal detectors is illegal or deep as 10 feet. A very large object, like an automobile, may be severely restricted. DON’T LET THIS HAPPEN IN YOUR COUNTRY! detected at 20 feet or more. • Always check Federal, State, County and local laws before The ability of the GEMINI-3 to detect objects at various depths searching. depends on several factors: 1. Ground Mineralization: The penetrating power of the • Respect private property and do not enter private property GEMINI-3 is adversely affected by the presence of without the owner’s permission. magnetite (a black iron oxide) and wet conductive • Take care to refill all holes and leave no damage. mineral salts. For example, an object that can be • Remove and dispose of any and all trash and litter found. detected at 15 feet in neutral ground may be • Appreciate and protect our inheritance of natural resources,... -
Page 6: Transmitter
BATTERY REPLACEMENT TRANSMITTER Power Switch: Pull out switch turns on power. 1. Turn either instrument (Transmitter and Receiver) over on its face and remove access plate with coin or large Ground Plate Jack: Used with the optional Ground Plate Assembly blade screwdriver. for the Conductive Trace Mode. 2. Lift the battery pack out carefully. Turn the battery Battery Level Meter: Gives a visual indication of battery strength. pack slightly, unsnap the battery connector and slip off the sleeve. Change all eight batteries. Slip the Replace batteries if below 5 on meter. sleeve back on, then reattach the connector to the pack. Slip the battery pack back into its 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 will give substantially... -
Page 7: Receiver
1. Dissolved mineral salts - Mineral salts become balancing and detecting. Also used as a battery test indicator. conductive when dissolved in water. As a result, the Sensitivity Control: Used to control sensitivity level. The circled “7” presence of saline water or water saturated soil high in salt content may render the GEMINI-3 useless. indicates the starting level used for Narrow Scan Inductive Search 2. Rough terrain - In very rough terrain it may be difficult Mode. to maintain the GEMINI-3 parallel to the ground, Headphone Jack: Accepts stereo or monaural headphones and resulting in frequent false signals. silences speaker when headphones are plugged in. (Stereo/mono 3. Irregularities in the overburden bedrock - The GEMINI- 3 may detect sharp changes in conductivity which headphones should be in “stereo” position.) are of no important geological significance. Power Switch: Pulling switch out turns on receiver. -
Page 8: Searching
2. Align the receiver panel holes with the upper- bottoms, gullies, outcrops and other physical features. handle threaded shafts. Tighten the lower black The ideal map on which to plot the conductive zones knob until it is finger tight. is a topographic and geological map of the proper 3. Turn the balance knob (with white arrow) until the scale. In this way it is possible to correlate the zones directly with the topography and geology, and thus spring is under tension (at least 10 turns). determine the possible reasons for the presence of the various conductive zones. Locating Placer Deposits A lot of prospectors have told us they would like to use a two-box for locating placer gold. In general, these deposits contain such a small amount of gold that it cannot be detected. Placer gold, however, is usually associated with a certain amount of black sand, and some placer deposits carry iron sulphide. Both of these mineral substances are definitely conductive, and may be detected by the GEMINI-3. It is through the detection of these minerals that the placer gold may be located. Figure 5. Assembly for Narrow Scan Inductive Search Figure 4. Narrow Scan Inductive Search... -
Page 9: Tuning
2. Set the receiver: Power: ON Power: ON Sensitivity: 7 Sensitivity: ZERO You should get a strong audio tone and meter 3. Slowly increase the SENSITIVITY control until the indication at this point. audio signal is heard, then reduce SENSITIVITY until CAUTION: Never attempt to tune the GEMINI-3 in the the audio just disappears. This is the point at which presence of metal objects likes cars, metal walls, roofs air coupling has been eliminated. or heavy metal reinforcements in any structure. Their presence will make proper balancing impossible. Operating . Pick the unit up by the handle and balance it so that 1. Locate the buried pipe by circling the contact it is level with the ground and at normal carrying point, keeping the receiver in line with the height (arm’s length). Five cm higher in the front is... -
Page 10: Operation
1/8- to 1/4-turn silence (null) 1. Once the two starting points have been established space. This is extremely important! If this procedure and the receiver tuned, walk away from the transmitter is not followed correctly, the GEMINI-3 will either in the assumed direction of the buried conductor. constantly give false audio and meter readings 2. Hold the receiver vertically to maintain a peak signal (sensitivity too high), or no signals at all (sensitivity or horizontally, face up, to maintain a null or minimum too low). The sensitivity will be correctly set and your... - Page 11 No peak objects can be located successfully with difficult to tune the GEMINI-3 will be observed if the receiver is too close to the this close to highly mineralized a larger, more widely traversed search ground. transmitter and direct air coupling is occurring. pattern.
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Page 12: Wide Scan Inductive Search
SEARCHING SEARCHING Wide Scan Inductive Search 3. Slowly increase the SENSITIVITY control until the audio This mode of operation is the preferred method for signal is heard, then reduce SENSITIVITY until the audio searching a large area quickly. Two operators are just disappears. This is the point at which “air coupling” required and the handle assembly is not used. has been eliminated. The Wide Scan Inductive Search mode is practical Operating only when searching for ore veins, pipes or cable 40 feet long or more. If the operators are too close 1. Keeping the receiver and transmitter sections in line, together, “direct air coupling” will result, meaning the receiver is detecting the Transmitter signal the two operators can now walk their predetermined directly through the air instead of through a buried...
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