Coil size comparisons related to depth of field

Well with the coil sizes ie 9 1/2" a 12" will give you up to 30% increase in depth but the trade off is the bigger coil
see's more ground so therefore it see's up to 30% more mineralization pr you may have to turn down the power a bit
so therefore you may even loose depth in extreme groud, If you set you detector up at a 1/4 power and take a target
you can map the shape of the coils field with a ruler and plot it on paper and if you do this at differant gain settings
you can see how much depth you loose when you turn it down, because you don't loose that much really, and you will
be less likely to over power the ground and blinding your discrimination so targets will be more accuritly ID
I have also put this on your other post because they are related.

Posted on: March 10, 2011, 01:17:13 PM

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With DD coils the field runs from front to back as one sid sends and the other recieves the signal and they put a blade into the ground
If you were to stand a book on the front edge then that would be how a DD puts it's signal in to the ground and if you were
to put a dinner plate on the back of the book with the book running from one edge to the other going across the middle of the plate
then that would be how the pattern would look and that is where the DDs hot spot is.

As for concentric coils these have a field alot like a mixing bowl that comes to a semi point and the coil has an outer coil
that sends the signal and an inner coil that recieves the return signal, The concentric will always go deeper on a size for size
bases ie you would need a 12" DD to equal that of which a 9 1/2" Concentric coil can achieve, but the DD is better on target
seperation and it handles mineralization better, alot of detector companies fit only DD coils to their machines but i feel it is
because the can't make their machines quiet enough to use a concentric coil so quite often you will find cheaper detectors
will acctually go deeper than those costing more than twice as much, and another point to remember is that a concentric coil
hits targets harder. and also concentric coils you can use in a wide veritiy of grounds but the DD can be used any where,
some companies do not offer a concentric as an option and i believe that this is because of what i stated earlier and i don't
trust them for not telling use how it really is, i how this is of use.

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No your not misunderstanding me with your concentric coil you can pinpoint by sweeping the coil left and right and pushing it forward
and backward without having to turn 90 deg and sweeping again with a DD you can pinpoint just as fast when you get use to it
i started of using DDs then i got machines with concentrics so i also bought DDs for my machines but you do loes depth on
the DD compared to the concentric, one coil i use no matter what is the big 12" concentric even in trashy sites although some
say you can't, well i say you can because i have found more in 2 1/2 weeks than everone else has in two years in this certain
field and as for sensitivity that big 12" is way more sensitive than all previous DDs that i have used, but i have all sorts of coils
for my machines, so there are coil for all situations and i do use them

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I will tell you a secrete, On the river Thames that runs through London there is so much junk there, the most sucessful hunters
are using Bounty Hunters because of their very fast recovery speed, you can find differant shape coils for Bounty Hunters but you
have the best of both worlds with the machines/ciols that have

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Tanx for the heads up AU.  I've got a little secret for you as well.

  I took the wife to that cemetary a little while ago and the first two targets that I found were a musket ball and a 1905 "V" whatever that is.  I will post the pics later after I know what it is.

  It sure doesn't look silver so I guess that I will be looking that up after this post.  I am eating some gumbo down here and feelin' good about this new spot bro.  Of coarse, the next thirty targets that I dug up afterwards were trash. :

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Tri City Ditty

		Quote:			Posted by homefire
	I thought this was common knowledge. Coil Size works like this: Larger coils go deeper but loose the ability to find smaller items. Smaller coils Don't go as deep but Find Smaller Items.  And you can pick between targets better. Rule of Thumb. A coil of any type can see about as deep as they are Wide.   DD type a little less but have ground Bal advantages.

  My biggest reason for this thread was to figure out if getting the Bounty Hunter 10 inch coil would really give me noticeable deeper depth or is it more important to have more power to increase depth.  I guess I did not say it like that but that is what is on my mind. 

  I will buy the 10 inch coil tommorrow and hope that it wil give me those extra couple of inches that I have been needing lately.  The town that I work in is pretty old relative to the surrounding cities but it is in a low lying area that has been filled in over time.  The older coins are certainly much deeper than if the land would have been higher back in the old days.

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Tri City Ditty