Fisher GEMINI-III Two-Box Metal Detector with deep-seeking technology, dual antenna system, and adjustable ground balance, designed for locating large, buried objects and caches at extreme depths.
Gemini 3
Fisher GEMINI-III Two-Box Metal Detector with deep-seeking technology, dual antenna system, and adjustable ground balance, designed for locating large, buried objects and caches at extreme depths.
Fisher GEMINI-III Two-Box Metal Detector with deep-seeking technology, dual antenna system, and adjustable ground balance, designed for locating large, buried objects and caches at extreme depths.
Fisher GEMINI-III Two-Box Metal Detector with deep-seeking technology, dual antenna system, and adjustable ground balance, designed for locating large, buried objects and caches at extreme depths.
Fisher GEMINI-III Two-Box Metal Detector with deep-seeking technology, dual antenna system, and adjustable ground balance, designed for locating large, buried objects and caches at extreme depths.
Fisher: Since 1931

Gemini 3

$959.00 USD
Free US Shipping
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Product Description

Designed for professionals in utility work, geology, and treasure hunting, the Fisher Gemini-3 is a two-box metal detector built for locating large, deeply buried targets. Unlike conventional detectors, the Gemini-3 excels at tracing ore veins, detecting underground tanks, or locating long-buried cache sites with unmatched depth and reliability. Its standout feature is its Voltage Controlled Oscillator (V.C.O.) audio target response, which allows for precise pinpointing even in challenging environments.


With the ability to detect large targets like 55-gallon drums at depths up to 10 feet—and even deeper for larger objects—the Gemini-3 delivers serious performance. It uses a crystal-controlled 81.92 kHz frequency and operates in both inductive and conductive modes, making it suitable for tracing pipes, cables, and mineral deposits. Dual search modes (narrow and wide scan) allow for flexible operation across varying terrains, while the analog meter and audio signals give clear feedback. Operators can fine-tune sensitivity for different conditions, and optional ground rod assemblies enable conductive tracing for buried lines with exposed access.


The Gemini-3 features a rugged yet lightweight frame with an ergonomic handle and padded grip for all-day comfort. Powered by standard AA batteries, it offers up to 30 hours of use on the receiver and 25 hours on the transmitter. The moisture-resistant speaker cone, weather-ready design, and durable construction ensure dependable operation in the field. Whether mapping ore zones or locating utility lines, the Gemini-3 offers reliable, high-performance detection in a professional-grade package.


PurposeDeep-seeking and cache locating for large buried objects, ore veins, pipes, and utilities. Ideal for prospectors, geologists, treasure hunters, and utility companies.

Specifications

  • Manufacturer: First Texas Products, LLC
  • Brand Name: Fisher Research Labs
  • Country of Origin: USA
  • Warranty: 2 Years
  • Technology: RF Induction / Voltage Controlled Oscillator (V.C.O.)
  • Frequency: 81.92 kHz
  • Operating Modes: 4 (Narrow Scan Inductive, Wide Scan Inductive, Inductive Trace, Conductive Trace)
  • Ground Balance: Manual (via Balance knob)
  • Discrimination: N
  • Target ID: No
  • Numeric ID: No
  • Fe Readout: No
  • Fe-Tone Audio: No
  • Audio: Yes, V.C.O. (Pitch and volume increase with signal strength)
  • Volume: Yes 
  • Sensitivity: Yes, Adjusted via knob
  • Depth Indicator: No (though analog meter indicates signal strength)
  • Pinpoint: Yes, via V.C.O. response
  • Memory: No
  • Backlight: No
  • Display: Analog
  • Weatherproof: Moisture-resistant speaker, but not fully waterproof
  • IP Rating: Not Rated
  • Stock Searchcoil(s): Not applicable (Two-box system)
  • Headphone Jack: Yes (1/4")
  • Weight: 7.5 lbs (3.4 kg) complete system
  • Battery Type: 8 x AA for Transmitter, 8 x AA for Receiver (Alkaline recommended)
  • Battery Life: Transmitter: ~25 hours; Receiver: ~30 hours
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    Manual

    Support

    For more information and to purchase, visit where to buy , email us , chat with us, or call us at 1-800-685-5050   for any questions.
    For repair service in warranty or out of warranty please fill out the RMA form.

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    Frequently Asked Questions

    What is the maximum detection depth of the Gemini-3, and what factors influence it?

    The Gemini-3 can detect large metal objects at depths of up to 20 feet or more. Detection depth depends on the target’s size, orientation, shape, ground mineralization, and how long it has been buried. For example, a 55-gallon drum may be found at 10 feet, while a car-sized object may be detected even deeper.

    How does the Voltage Controlled Oscillator (V.C.O.) enhance target pinpointing?

    The V.C.O. system increases both pitch and volume as you approach a target, allowing for more precise pinpointing without having to readjust sensitivity constantly. This real-time audio feedback makes it easier to locate the center of a large conductive target.

    What’s the difference between Inductive and Conductive tracing modes?

    Inductive tracing relies on detecting an electromagnetic field induced through the ground, useful for locating buried objects without direct contact. Conductive tracing uses a Ground Rod Assembly to send current directly through an exposed section of the object, offering better accuracy in crowded or noisy environments.

    Can the Gemini-3 detect small targets like coins or nails?

    No, the Gemini-3 is specifically designed for large, deeply buried metallic objects. It does not detect small targets effectively and should not be used for coin or jewelry hunting.

    Is the Gemini-3 affected by ground mineralization or black sand?

    Yes, heavy mineralization and conductive salts in wet soil can significantly reduce detection depth. In highly mineralized areas, tuning becomes more sensitive, and achieving proper balance and nulling is more challenging.

    How do I know if I’m experiencing direct air coupling during a wide scan search?

    If the Receiver detects the Transmitter signal directly through the air (rather than through a buried conductor), the signal strength will not peak over the object. To resolve this, increase the spacing between operators or lower sensitivity until the air-coupled signal disappears.

    Can the Gemini-3 be used to trace non-metallic pipes or conduits?

    Only if they have a conductive tracer wire or if you can induce a signal via direct connection in conductive mode. Non-metallic pipes without any conductive components cannot be traced with this detector.

    How do I correctly balance the unit for Narrow Scan operation?

    Power on both the transmitter and receiver, set the sensitivity to 7, and slowly adjust the Balance knob until the audio nulls out with no signal. Fine-tune sensitivity until you achieve a 1/8 to 1/4 turn of silence—this ensures optimal performance.

    Why does the signal fade when tracing a long conductor, and how do I fix it?

    Signal fade occurs due to distance or attenuation through the ground. Increase sensitivity gradually to maintain detection. If the signal is still weak, reposition the Transmitter closer to the Receiver or the trace line.

    What are common sources of false signals when using the Gemini-3?

    False signals can result from saline soil, rough terrain, nearby large metal objects, or abrupt changes in bedrock conductivity. Always tune the detector in an interference-free area and adjust sensitivity and balance properly to minimize noise.

    Testimonials

    What Our Customers Are Saying

    '...he found his first coin. A 1946 wheat. I'm glad to say we have a new Digger in the family."





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    Landon Howlett

    Fisher F70

    This is a Union Officers belt plate from the Civil War, it was found at a G.A.R. 1895 Civil War reunion encampment...





    JimDoan

    Jim Doan

    Bounty Hunter Quickdraw II

    '...great detector please keep me informed on the new machines coming out i got pictures of your detectors for years finding things in fields that have been hunted by everything till the First Texas hit the ground.'


    RyanVecchio1

    Ryan Vecchio

    Bounty Hunter Platinum

    "Great contact information, wonderful interaction and the product is wonderful. I will expand my accessories, new usable work products, thanks for this convince and an all USA (EL Paso TX) buy local products."
    JamesKSample

    James K. Sample

    Fisher TW6

    '...i pulled the trigger on it just in time to detect the new yard my son was on and all i can say is this machine is one serious coin shooter the first yard I scan with it I get my first silver quarter (1946) and my first Morgan dollar (1900) which was 11in .

    DaveBrumfield

    David Brumfield

    Bounty Hunter QuickDraw Pro

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