BELDA'S Detector Sales- Metal Detectors, Gold Prospecting Equipment





coiltek coils

There are 5 main guidelines to remember when choosing a coil for your detector:

Coil Size & Depth - A larger coil will typically find targets hidden deeper in the ground, but they can be less sensitive to smaller targets. A smaller coil is typically more sensitive to small targets, but does not go as deep as a larger coil.

Mineralization - A Monoloop coil will often have improved performance over a Double D coil but can be more difficult to ground balance and therefore possibly more noisy. A Double D coil is often more stable in heavily mineralized areas.

Terrain & Vegetation - A larger coil requires more open ground whereas a smaller coil can be easier to guide in tight bush or rough terrain. Obviously a smaller coil is also lighter weight than a larger coil.

Discrimination - In areas where discrimination is required, a Double D coil will provide a more accurate ID. In high trash concentrations, a smaller coil is preferable.

Search Pattern - A Double D coil will typically provide a 'blade-like' detection pattern from the toe to the heel of the coil, which gives excellent ground coverage. A Monoloop coil has a detection field that is typically cone shaped, which requires overlapping of sweeps to ensure thorough ground coverage.

Double D coils VS Monoloop coils

Double D -
They offer a full width for search pattern.
Produce less ground noise and require less tuning (with a manual balance detector)
They give off less false signals because of hot rocks.
In high mineralized ground they offer greater depth.
Less sensitive to outdoor interference.
Basically, they are good for high mineralized soils.

Monoloop coils-
Good for low mineralized soils.
Usually, lighter in weight.

Choosing a optional coil for your detector still depends on the soil, the size of potential nuggets
and weight should be considered. Please call me and I will help you choose the right coil

Minelab Introduces...
Series Accessory Search Coils
An completely NEW line of PREMIUM high performance coils- exclusively designed for MINELAB GP and SD Series Gold detectors!
Precision designed, engineered, built and tested by Minelab
The right coil for the right job. Read on...
Minelab Commander Coils
The technology used in Minelab's gold detectors has become more and more advanced with time. Ensuring that our coils have kept pace with those advances in technology has been equally important to Minelab, so that our customers can be assured that their coils are the best match
for their detector investment. Minelab Commander series coils have been designed by the Minelab team of scientists & engineers, specifically to match the requirements of Minelab technology and to give optimum performance.
All the Commander series coils are made using the very best quality components like gold plated plugs, low-noise shielded cable and multi-strand Litz wire. Litz wire, is made of numerous, very fine individually insulated strands. The insulation prevents the windings from creating eddy currents and thereby "seeing themselves" and transmitting a false signal. Litz wire has an advantage over other wire because its high surface area gives it a greater transmission ability. This translates into a more powerful, energy efficient coil for its size.
Commander coils are well made, robust coils, designed to cope with the rugged conditions of the gold fields. Designed to get the most out of your GP series detector, the following coils will also enhance the performance of your SD series machine.
Choose the right coil for the job.
large deep nugget
highly mineralized
open ground
heavy scrub
iron disc.
8" round monoloop
10" elliptical Double D
11" round monoloop
15" round monoloop
15" elliptical Double D
18" round monoloop
18" round Double D

I have tested these coils and the Ellipticals are more stable and quiet than the previous Minelab coils.  They are also lighter, the small elliptical 5x10 only weighs 16 oz's. The 12x 15 is 2lb's 7oz's. With the new LITZ wiring they will out perform the previous stock coils.

read my review

Available NOW from Minelab in these sizes and configurations:
15" x 12" Semi-Elliptical Double D - Greater depth and more ground coverage than the 11" DD, It provides stable operation in all soils. This is a great coil for all-round use in highly variable soils and a lighter, more maneuverable alternative to the 18" DD when seeking out large nuggets in heavy mineralization. Its semi-elliptical design provides impressive sensitivity for its size. MSRP $
15" x 12" Semi-Elliptical Monoloop - On larger nuggets this coil has better depth than the 11" Monoloop and the 15x12" DD, and it is very sensitive for its size. It is great for searching open areas for new patches and when seeking out deeper nuggets in areas that are too vegetated to allow effective use of the 18" monoloop. It is an extremely stable coil which runs smooth in all but the worst soil conditions. This coil will become a favorite for many operators. MSRP $
10" x 5" Elliptical Double D - This is the coil that every prospector should carry because of its endless versatility. Great in thick scrub, heavy mineralization and high trash; it has superb sensitivity and surprising depth for such a small coil. It is also great for pinpointing deep targets found with one of the larger coils and is extremely stable in all soils. MSRP $
8" Round Monoloop - The most sensitive of the Commanders, the 8" round provides the best depth on sub-gram nuggets in light to moderately mineralized soils. A popular coil for use on old diggings, it is also a great coil for detecting in heavy vegetation. MSRP $
11" Round Monoloop - A lighter, more sensitive and deeper seeking coil compared to its Double D brother, the 11" Monoloop is a brilliant coil for almost any situation. The 2nd most sensitive Commander monoloop, it is also one of the most stable monoloop coils available and will provide a smooth threshold in most soil types. MSRP $
18" Round Monoloop - Superb depth and high sensitivity in low to medium
mineralization. This coil will find targets in heavily worked areas where other operators have given up. MSRP $
18" Double D - A serious coil for the serious operator! The 18" DD punches deep through heavy mineralization, while running smooth to allow you to hear those mellow, deep nugget responses. MSRP $

Gold Through Technology
In designing the range of Commander coils, Minelab's Product Development Department used the latest in computer imaging programs to create 3D maps of the performance and search pattern coverage of each of the coils. Shown below are a couple of typical mapping diagrams quite clearly demonstrating the blade like search pattern of a Double D coil and the cone shaped pattern of a Monoloop coil.
Commander DD coil response
Commander Mono coil response

What's The Difference?
Double D coils provide a blade-like detection pattern for accurate ground coverage. They handle heavy and variable mineralization better than monoloop coils and they allow the use of the Coil switch found on the GP series. Pinpointing is done along the center of the coil.

Monoloop coils are more sensitive and deeper seeking than an equivalent sized DD,
but can become erratic in very mineralized soils. The detection field is cone shaped,
so it requires overlapping sweeps to ensure thorough ground coverage at maximum depth.
Very sensitive around the outer rim, the coil can be tilted on edge when pinpointing tiny targets.

Maximize the gold seeking power of your GP Detector NOW!

no sales tax in Oregon


Commander coil size

this is the 12 x 15 next to the standard 11"

 Product Review of New Minelab Commander Series Coils manufactured by Minelab for the SD & GP Series Dectectors
By Mark Belda in cooperation with NINA* Labs

We were pleased when Minelab USA requested that we provide a field test of their new Commander series of elliptical coils.  They were kind enough to provide us with 3 sizes to test, namely their new 5” X 10” Double D, a 12” X 15” Monoloop and a 15” X 12” Double D.

As you probably already know their mainstay offerings are an 8” Round Monoloop, an 11” Round in Double D or Mono, and an 18” Round in Double D or Mono.  These sizes have proven throughout the years to be very good, but left some gaps in size and performance.

Evidently what makes the Commander Series a more advanced technology is that they use multi-strand Litz high frequency wires for the coils.   These very small, individually insulated woven strands are separated precisely enough to avoid false signals generated by the many strands detecting each other.  This should make for low noise, and more energy efficiency.  Thus, we would expect a more powerful and stable coil for its size.

On March 5, 2005 my son Errol and I took a 3 day trip to an old but fruitful placer site in Nevada.  It has produced gold in quartz in pieces weighing up to 4 ounces each (I might be persuaded to sell you a map).  A friend showed us a place in the area that would provide a challenge for our test.  

When we arrived the first thing we noticed was all the iron trash.  With this in mind we decided to begin with our GP3000 detector and the 5” X 10” DD coil.  There were numerous piles of old tailings and we were able to pick out non-ferrous targets ( i.e. lead, copper and brass), and yet still identify the iron.

We were very happy with its performance.  This small, but sensitive coil will be very popular for hunting bedrock, tight areas in midst of boulders, in heavy brush, and tailing piles.  It only weighs 16 ounces.

Next we tested the 15” X 12” Semi-Elliptical Double D coil.  Its greater size should provide superior and faster ground coverage.  Indeed, we found it to be very stable and produced very little noise.  It was easier to maneuver than 18” Rounds that we have used.  Double D coils are my choice for areas with high amounts of trash, because the iron discriminator will only work with them.  This helps ignore a lot of the shallow iron trash.  

We feel that this will be a very useful coil for where we prospect in Oregon and Arizona, because of all the melon size Hot rocks.  In fact this coil should prove the best choice for ground with high mineral content, hot and cold rocks.

Next we tried the 12” X 15” Monoloop on our GP3000 set in fixed, sensitive and then deep modes.  We were able to pick up old 22 caliber bullet heads as clear targets to a depth of 11”.  We tested it by swinging it in deep Bitter brush and often bumped it against the many hidden rocks.  It ran without false signals and proved to be like a Tank in durability.

We found everything Minelab says about the coils to be true.

We give the new coils from Minelab thumbs up.

back to minelab page

Errol Belda
2210 SE Oak Grove Blvd.

Portland, OR. 97267

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