Question about using a larger coil.

[fueller]

Hi group. Without being brand specific, what can I expect if I spend the money and go from an 8" coil to a 10"? I have read that going to a larger coil will drop my sensitivity for small items and increase it for deep larger items. Assuming that I'm mostly looking for coins, and a dime is the smallest size, what can I expect in the real world. Will I miss more dimes that are deep (because they are small) or find more. This probably sounds like an ignorant question but I want to know what I can expect if I'm going to spend the money.
I know I can't get an exact answer for this next question, but what kind of ballpark increase in depth can I expect by using a 2" larger coil? Also, I could forget the 10" and go for a 15" wot or similar but I think this would be overkill for everyday use. Any thoughts?

 

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[Lowbatts]

If you are considering the WOT, then I guess you are not talking about a Fisher brand. That's what I use. Radio electronic principles being the same though, I would tell you my experience is that the larger coil obviously does not have as good target separation. So if a pulltab is the predominant signal because that old CC Seated liberty coin is beneath it and off to one side, your gonna have to dig that pulltab before you get that silver signal.
Larger coils are fine in sand, where it is no big thing to dig every signal, but if you are not digging every signal in dirt and you are relying on target id then you will miss targets with the bigger coil.
The only time I go to the big coil off the beach is when I know I'm in a clean environment and only have old targets to hunt. There is better depth and the dimes definitely show up with the bigger coil.
A lot of members here actually prefer to go to a smaller coil as an upgrade rather than a larger one. This because target separation is better and depth loss is minimal on the average high-end machine using a smaller coil.

 

[Jim McCulloch]

Fueller, changing coil sizes will have incumbent advantages and disadvantages. At the same power setting, a 10" coil will get about 20% more depth then an 8 incher. But, the 10" has about 56% more surface area then the 8, making the 10 incher less suitable for use in a trashy area. Also, depending on your soil conditions, using a 10 incher MAY require a slight reduction in power, so you will get less of a depth increase if you have to use less power. Yes, the bigger the coil, the less sensitive it is to smaller targets, but when talking about dimes, this won't be a real issue. As regards 15" coil, coils this big are rarely used for coin hunting, due to the fact that such a size virtually guarantees too much "target masking" due to trash, and, swinging such a coil is a pain. Such coils are usually reserved for deep relic hunting, or cache hunting. HH Jim

 

[Hoser John]

Without knowing your detector manufacturer it's a hard call. There are so many different kinds of coils now for different machines concentric,deep search,dd,coiltek,bigfoot,eliptical,and on and on.Call your mfg. tech support,explain your situation,machine,and most important-the rough area your gonna work.All beaches are different-some all sand,some all black sand,mixed,heavy trash or relatively trash free?? On heavy trash beaches I like a smaller coil to work around the heavy trash and for nugget shooting too. Tons a au 2 u 2-John

 

[coinshooter]

I have both coils (a 10" minelab) and a 15" WOT. I bought the WOT for sand, but they are all right above. Sand is the only place you want to use one of these, and mostly in the winter when there is not as much trash out there. Believe me, digging a 15-20" deep hole in sand is hard enough. I am thinking of selling mine, but haven't given it the full work out yet. I will try it again during the winter when targets are slim pickins. As for the 10", I only have one complaint. It's too heavy for more than 2 hrs hunting time. Even with the box removed, the 10" minelab coil is HEAVY (the WOT is fairly light). But, on the other hand, I have found more gold with this coil and machine than I ever have (see my posts under "recent finds"). I would say do it, switch to the bigger coil (the 10") but avoid the WOT, I am overall happy with my 10". Maybe I should move in the other direction myself and get an 8" minelab. Don't know what your machine is, but I am very happy with mine. wink

 

[Jim Mayo]

A larger head will give you more depth. I can find precussion caps with my 20 inch head. Large heads will not discriminate as well as a small head and you will dig some big and deep holes. If the area is reasonably clean with no junk, it works fine. For most relic/coin hunting a 10 to 12 inch coil works just fine and you will see approximately 2 to 3 inches more depth than an 8 inch coil. Pin pointing in grassy areas is a problem but I dig these areas with a entrenching tool by taking a 6 inch square plug. The detector in the pic I use only in clean woods and fields. I have an 8 inch coil for yards.

 

[dneyedli@res1.mts.net]

Depends on what machine your using! I have a 10 inch but never use it. No need to, as I get 15 to 20 inches in sand with a 8 inch. On soil, up to 15 inches for a coin. All these new detectors coming out offering superior depth seem to come with a 10 inch coil. My rookie friend, who uses a Classic ID, bought a IDX because it offered greater depth. Well of course it comes with a 10 inch coil instead of a 8 inch like the the one he already had. I told him that he could of saved $600 and just bought a larger coil.
If your talking about a WOT then I assume you are using a Minelab which already has great depth and chances are you don't need such a big coil.
To help us out, maybe you can tell us what machine your using
H.H. Dave.

 

[Chiz]

Ok... I am confused here.... one post has the bigger coil going deeper and another has the smaller one going deeper. I would assume that a sniper coil would go deeper than a standard because of the concentration of the signal. Am I right on this? I was thinking about getting a sniper coil for my MXT for hunting old "party" spots and abandoned towns with a lot of iron trash. Am I on the right path with a sniper (8") ?

 

[Lowbatts]

The smaller coil does not go deeper, it does however have much better target separation.
The larger coil covers a larger area, so it will inherently suffer from the effects of target masking to a greater degree than the smaller coil.
Bottom line, large coil better in clean target environment where depth is key, smaller coil better in trashy area if you favor id mode or want to discriminate in target selection.

 

[Jim Mayo]

Lowbatts is absolutly correct. Small coil gets less depth than a larger one.

I watched a fellow with a tesoro using a 3 inch coil find a pocket full of buttons hunting in a very trashy area where 1920 era houses had been demolished. He wasn't digging them deep but was finding them fairly shallow among the coal clinkers and tons of trash ranging from lead pipes to nails. I took my Wilson with the 8 inch head to the car since it would not hunt because of the large amount of trash and started eyeballing. Finally found an eagle button that way.

 

[Chiz]

Hey thanks... makes sense to me! Much appreciated!!! I was looking at it from teh wrong perspective. I figured it was like a radar, the more concentrated the beam, the further it tracks.... Thanks again...

Chiz
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