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Will a Larger Coil Cover MORE Area?

Yeah but infest the ground with iron and pulltabs and try to find a quarter.I ran 3 coils over the same area with the same machine from largest to smallest.The bigger coils confused the machine.The smaller coil you could watch the numbers and pick out a quarter signal.The larger coils never saw a quarter at all.

If youbase it on trash areas then the smaller coils pick amongst the trash, infact if its only against trash for the at pro as the coils suggest then the supersniper 4" is going to be best although your looking at 4" max depth but for most clad thats about their depth anyway.

if covering fields like sports fields i tollerate the extra weight of the 8.5X11 then spend twice as long looking with the smaller lighter coil, i may have to switch arms a few times but as my left is getting pretty good as an even sweep its no trouble, a four hour hunt with the large coil beats a 5% increase in finds with the smaller coil but taking 8 or 9 hours.

With the size of my sweep and the maximum stem length i can cover over maybe 9 or 10 feet so its not a major timeage anyways...

I'd buy a 14" double 'd' coil if they made one for the at pro that didnt weigh as much as a cinder block on the end of a broom
 
Today I went out and found a clean area of the yard and buried a dime the depth of my lesche blade making sure it was flat. I checked it with the CTX and a BH Discovery 3300. The CTX had no problem showing it. The 3300 picked it up but the signal was bouncy. Then I place a staple at 2 inches deep above the dime. The CTX still showed the dime though the signal was more broken. The 3300 was mostly silent. I then placed a small 1.5" nail in the hole at about 2". The CTX showed the iron and dime but the dime was much more broken up, to the point that I would not have dug the signal (unless I was bored). The 3300 was silent. Then I placed a larger 3" nail at 2 inches. This finally completely masked the dime for both machines.

This was not a very scientific test but I can say that small metal fragments like bird shot and staples are unlikely to mask out a coin, even at depth for the CTX. Small nails could very easily make you pass up a good target, unless "you" are being less discriminate. Large metal objects above a good target will absolutely mask a target.

The Bounty Hunter Discovery 3300 is a great machine but obviously not on the level as the CTX. But, I got mine for $160 on ebay brand new. It is an ideal starter machine, I think even better than the f2.

I notice that the article was written in 2005, is it possible that technology is addressing the issue? Even though my test showed that things may have gotten better, it does not mean that masking is not something to consider. Take the Rattlehead's story for instance. I a circumstance like that, he may do well by stirring up the ground just to redistribute things and possibly unmask more treasure. I have read that he plans to do so.

I find this all very interesting.
 
Well that was a very nice test Finnerman. So I am guessing with the CTX you are running what they call the soil/coin setting so that you get the target trace correct?
 
Really great thread so far!

Soooooo...... getting back to my original question, do you think a 12" concentric will cover more ground than an 8" concentric in the same amount of time, or will it just search a little deeper? :cool:
 
At same depth as 8" faster. At the added depth about the same provided the RX coil of the 12" is identical diameter as the 8".
 
One thing about the DD coil is that it sure knows how to find bottlecaps! The smaller coils on the Garrett Ace's dont seem to find them as easy.
 
Soooooo...... getting back to my original question, do you think a 12" concentric will cover more ground than an 8" concentric in the same amount of time, or will it just search a little deeper? :cool:

No.

When we use a unit with a small coil, say a sniper or a 6", most realize that the smaller coil is on for the reason separation between signals, as a very trashy area is the reason we put the smaller one on anyway.

Our swing length becomes shorter as we don't tend to swing out wide and round to the sides. The trash alone keeps our swing short as the checking then re- checking of targets, and the more often down on one knee dig time limits us to a smaller area

When moving on to, or setting up in an area where an 8"or 9" concentric is wanted to be used, due to far less signals, then the thought of putting on a 12" concentric would come to mind as well, especially if we think it would be deeper ground ie: a long but narrow depression that would hold a couple of inches of water two days after rain as opposed to the grass area a little higher directly nearby.

The extra depth of the 12" is there, for sure, but so is the very bad habit of most detectorists taking a bigger coil, and making a swing, where back tip of the coil has only placed it an inch or so within the mark that the front tip was on the previous swing, as well all half way round the body on each side. The amount of ground not detected in that scenario, is massive, at least the amount of a full 180 big wide swing around each side of the body. The area detected that hunt, would leave 1/3rd of the entire area undetected.

If both our theoretical 12" and "8 concentrics were swung short for True Coverage, the 12" would gain nearly 2" a swing, about 6" a yard. But some are quite happy to cherry pick the first few inches of dirt, and like a quick hunt. It's just a matter of saying goodbye to 1/3 of the mid to deep targets.
 
And I think we should assume that the detectors used in the theoretical use of the 12" and 8" coils, should be at least be amoung the quality TID and VID units.

And if that's the case, then the 12" concentric, by using a correct shortening of swing to maintain True Coverage, would end It's day with better finds in that less trashy area over the 8". Merely due to slightly better information and discrimination at the slightly better depth.
 
Good question Terey :)

The problem with this thread is most are basing their information of a supposed detection field a coil emits on sales and marketing collateral from certain manufacturers used to try and sell more detectors and more expensive coils as opposed to actual scientific information from actual detector design engineers on how coils work. The purposed detection field emitted by DD and concentric is little more than a detecting 'urban legend' and I highly doubt any detector design engineer will try and present an argument to the contrary. No one has ever 'proved it' with scientific data to support the marketing designed diagrams yet most accept the illustrations as a 'convenient' explanation even though they are not accurate.
David Johnson, the most accredited detector design engineer over the past 30 years has written an essay on the proposed field emitted. He has designed more detectors and coils for 6 major manufacturers including 2 generations of Fisher than any other one person or company so I feel that makes him an authority (at least the only one to comment). He is the only person that has actually designed a detector to comment on this subject in black and white along with a few other individuals well respected in the industry confirming this myth in books and on technical forums. I have tested many coils of varying shapes and sizes from many manufacturers and while my tests are not as advanced as the design engineers they confirm the myth of the detection field shape some manufactures sales and marketing departments have turned into gospel with end users.....

If another manufactures design engineer wants to tell us about how a concentric emits a cone and a double D emits something different in the ground with data and mapping information to back it up I will be glad to listen but I am confident none will….
If anyone can scientifically reports factual findings to endorse the purposed detection field some manufactures have presented in marketing material (proves it) debunking what DJ has put in black and white on a company website I would love to hear it.
Until then I will believe what David Johnson formerly with Fisher in the early 80’s, Whites Electronics, Tesoro, Troy Shadow, Fisher, Bounty Hunter and Teknetics has to say regarding it.
http://www.fisherlab.com/hobby/dave-johnson-essays.htm
Read;
Search coil Field Shape
About Search Coils

Mike
 
From that link http://www.fisherlab.com/hobby/davejohnson/searchcoils%20essay%20revised.htm

Searchcoil size

Most standard searchcoils are approximately 8 inches (20 cm) in diameter if round, or approximately 10 inches (25 cm) in length if elliptical.

Larger searchcoils allow covering more area with each sweep, and offer a slight increase in depth on medium and large size targets. Unfortunately they are heavier, more difficult to pinpoint with, tend to lose small targets, and provide poor target separation.

Small searchcoils provide superior target separation (important in trashy areas) and ability to detect smaller targets (important in gold prospecting). Of course they don’t cover as much ground as a standard size coil. However (and this may surprise you) small searchcoils usually have nearly as much depth capability as standard size searchcoils.
 
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The problem with this thread is most are basing their information of a supposed detection field a coil emits on sales and marketing collateral from certain manufacturers used to try and sell more detectors and more expensive coils as opposed to actual scientific information from actual detector design engineers on how coils work. The purposed detection field emitted by DD and concentric is little more than a detecting 'urban legend' and I highly doubt any detector design engineer will try and present an argument to the contrary. No one has ever 'proved it' with scientific data to support the marketing designed diagrams yet most accept the illustrations as a 'convenient' explanation even though they are not accurate.
David Johnson, the most accredited detector design engineer over the past 30 years has written an essay on the proposed field emitted. He has designed more detectors and coils for 6 major manufacturers including 2 generations of Fisher than any other one person or company so I feel that makes him an authority (at least the only one to comment). He is the only person that has actually designed a detector to comment on this subject in black and white along with a few other individuals well respected in the industry confirming this myth in books and on technical forums. I have tested many coils of varying shapes and sizes from many manufacturers and while my tests are not as advanced as the design engineers they confirm the myth of the detection field shape some manufactures sales and marketing departments have turned into gospel with end users.....

If another manufactures design engineer wants to tell us about how a concentric emits a cone and a double D emits something different in the ground with data and mapping information to back it up I will be glad to listen but I am confident none will….
If anyone can scientifically reports factual findings to endorse the purposed detection field some manufactures have presented in marketing material (proves it) debunking what DJ has put in black and white on a company website I would love to hear it.
Until then I will believe what David Johnson formerly with Fisher in the early 80’s, Whites Electronics, Tesoro, Troy Shadow, Fisher, Bounty Hunter and Teknetics has to say regarding it.
http://www.fisherlab.com/hobby/dave-johnson-essays.htm
Read;
Search coil Field Shape
About Search Coils

Mike

That is a really informative website Mike! Thanks!
 
Just a thought... Have any of the manufacturers placed receptors in the ground to actually see what the signal sweep is, by reproducing the electro-magnetic field on a computer?

I would guess that the signal is in sine form, and they would be able to precisely determine the length and width.
 
The problem with this thread is most are basing their information of a supposed detection field a coil emits on sales and marketing collateral from certain manufacturers used to try and sell more detectors and more expensive coils as opposed to actual scientific information from actual detector design engineers on how coils work. The purposed detection field emitted by DD and concentric is little more than a detecting 'urban legend' and I highly doubt any detector design engineer will try and present an argument to the contrary. No one has ever 'proved it' with scientific data to support the marketing designed diagrams yet most accept the illustrations as a 'convenient' explanation even though they are not accurate.
David Johnson, the most accredited detector design engineer over the past 30 years has written an essay on the proposed field emitted. He has designed more detectors and coils for 6 major manufacturers including 2 generations of Fisher than any other one person or company so I feel that makes him an authority (at least the only one to comment). He is the only person that has actually designed a detector to comment on this subject in black and white along with a few other individuals well respected in the industry confirming this myth in books and on technical forums. I have tested many coils of varying shapes and sizes from many manufacturers and while my tests are not as advanced as the design engineers they confirm the myth of the detection field shape some manufactures sales and marketing departments have turned into gospel with end users.....

If another manufactures design engineer wants to tell us about how a concentric emits a cone and a double D emits something different in the ground with data and mapping information to back it up I will be glad to listen but I am confident none will….
If anyone can scientifically reports factual findings to endorse the purposed detection field some manufactures have presented in marketing material (proves it) debunking what DJ has put in black and white on a company website I would love to hear it.
Until then I will believe what David Johnson formerly with Fisher in the early 80’s, Whites Electronics, Tesoro, Troy Shadow, Fisher, Bounty Hunter and Teknetics has to say regarding it.
http://www.fisherlab.com/hobby/dave-johnson-essays.htm
Read;
Search coil Field Shape
About Search Coils

Mike

You are right Mike.
http://metaldetectingforum.com/showthread.php?t=112887
 
And the question still remains..

The problem with this thread is most are basing their information of a supposed detection field a coil emits on sales and marketing collateral from certain manufacturers used to try and sell more detectors and more expensive coils as opposed to actual scientific information from actual detector design engineers on how coils work. The purposed detection field emitted by DD and concentric is little more than a detecting 'urban legend' and I highly doubt any detector design engineer will try and present an argument to the contrary. No one has ever 'proved it' with scientific data to support the marketing designed diagrams yet most accept the illustrations as a 'convenient' explanation even though they are not accurate.
David Johnson, the most accredited detector design engineer over the past 30 years has written an essay on the proposed field emitted. He has designed more detectors and coils for 6 major manufacturers including 2 generations of Fisher than any other one person or company so I feel that makes him an authority (at least the only one to comment). He is the only person that has actually designed a detector to comment on this subject in black and white along with a few other individuals well respected in the industry confirming this myth in books and on technical forums. I have tested many coils of varying shapes and sizes from many manufacturers and while my tests are not as advanced as the design engineers they confirm the myth of the detection field shape some manufactures sales and marketing departments have turned into gospel with end users.....

If another manufactures design engineer wants to tell us about how a concentric emits a cone and a double D emits something different in the ground with data and mapping information to back it up I will be glad to listen but I am confident none will….
If anyone can scientifically reports factual findings to endorse the purposed detection field some manufactures have presented in marketing material (proves it) debunking what DJ has put in black and white on a company website I would love to hear it.
Until then I will believe what David Johnson formerly with Fisher in the early 80’s, Whites Electronics, Tesoro, Troy Shadow, Fisher, Bounty Hunter and Teknetics has to say regarding it.
http://www.fisherlab.com/hobby/dave-johnson-essays.htm
Read;
Search coil Field Shape
About Search Coils

Mike

Great post Mike. So.. Can you really cover more ground FASTER, with a 12" concentric coil than you can with an 8" concentric coil in one hour?
 
Soooooo...... getting back to my original question, do you think a 12" concentric will cover more ground than an 8" concentric in the same amount of time, or will it just search a little deeper? :cool:

It will cover more ground. I have used FBS detectors for many years and I have never noticed a difference in depth using a larger coil. All I noticed is my arms getting tired more quickly.

For years I felt bigger is better/deeper. Over time and through much experimentation i've learned to accept that it's just not true. My tiny 5" coil on my T2SE can find anything your larger coil can find. What will actually go deeper is a different machine using a different search method. VLF, for example, will go much deeper than FBS. You won't see a GPX user using a giant coil while relic hunting. It's just not necessary and can cause you to miss targets in target infested areas.

Boosting your settings will make it go deeper too. Sens -> depth, but the downside is chatter/falsing.

HH!
 
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