Search Coils & Covers
For every type of metal detector there are several different types of coils to go with it. Not every search coil is created equal. They come in all different sizes, shapes, and configurations.
The search coil is one of the most important parts of a metal detector. Whereas the control box is considered the “brain” of the metal detector the coil might be considered the “eyes”. The coil sends out a radio wave at a certain frequency and receives it back. Without the coil, the brains can’t “see’ what is in the ground to tell control box, which in turn tells the user, what the underlying target may be.
We stock all of the manufacturer provided search coils and offer them all. We also have several different aftermarket search coils for metal detectors such as Coiltek, Detech, and the ever popular Nel search coils.
Two main variants of search coils are the concentric and the Double-D search coils:
Concentric Search Coil
The most widely used and economical search coil, the concentric coil is preferred by many detectorists. The concentric coil gives superior depth and a larger detection area in soils with low to moderate mineralization. More heavily mineralized soil can sort of “jam” a concentric coil and a DD may be preferred. A larger coil generally means you get more depth. Note in the diagram the detection field of the Small “Sniper” Coil on the right. Going too deep or too big with your search coil can be a bad thing in an area with too much trash. A large coil may detect so much junk at one time that more valuable targets are missed. Sniper coils are very good in this scenario. Their small detection field can help detectorists more easily pick through numerous targets.
The “DD” coil is so named because of the shape of the two coils which overlap at the center unlike the traditional concentric coil where one coil lies inside the other. This overlapping, and subsequent signal cancellation on certain areas of the coil, creates a unique shape to the field of detection. Instead of a bowl-shaped field of detection below the surface, the result is more of a knife-shape. As illustrated in the diagram, the “slice” allows you to differentiate between two nearby targets better than a traditional concentric coil. As you waive the coil over the recovery site, you will get two distinct signals back to back as opposed to an erratic/jumpy signal. This is especially useful in very trashy areas. The only drawback is you have less of a detection field, and some argue that you lose depth with the DD.
Why use a search coil cover? Your search coil is a vital component to your metal detector. It is important, especially for resale purposes, to protect this important part of your metal detector. Thus, it is wise to protect your coil with a coil cover. Search coils are relatively inexpensive and worth the investment. Additionally, you will lose zero sensitivity or depth by using one.