William1221
Member
I'm confused I was told that overlapping with the DD coils coil was not necessary. If you look at a diagram its central wedge configuration it seems to me that the signal is not covering the total coil what am I missing?
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Coil Question
- Thread starter William1221
- Start date
Will,all coils require an overlap to have the best chance to find your target.The DD coil has a more more efficient scan than a concentric coil,but still requires an overlap.Place a coin on top the ground and practice.Nothing never works like a text book example,but the DD coil has a scan advantage over the same size concentric coil.
Critterhunter
New member
And I'd say that overlap is also a good thing because of potential target masking. Let's say you've got a large piece of trash between you and a good target. If you didn't overlap your sweeps then there's a good chance your only pass over the good target also was seeing the large piece of junk, maybe causing you to miss it. But, if you overlapped your sweeps then you'll get to a point with one pass where the coil is now just past the large junk target and is only seeing the good one. For that reason even hunting with something tiny like a S-5 coil it's still a good thing to overlap sweeps. The more the better, and it can help even a large coil to unmask targets that somebody with a smaller coil who wasn't overlapping could easily miss.
William1221
Member
Something just popped into my head,Ron I was wondering if the concentric coil with its more pointed configuration might be better in some instances. Its a more concentrated point of contact with the signal and its picking up less ground interference ? Something like we have been discussing about sensitivity. Sometimes less is better???? The wedge like configuration compared to the inverted triangle design . If the depth of penetration is the same with both coils perhaps concentric may have a place in our tool chest. just a thought.
Will,I have used a lot of metal detectors with concentric coils and have found just the opposite in the field.Most 5 inch coils concentric or DD will separate targets very well.The small 7.25" 800 Tornado does this just as good as these sniper coils and retain a greater depth of 9" with some coin in good ground conditions.One of my favorite detectors is a Fisher 1236X-2 with a 5 inch concentric coil a great combination.For coin hunting though the Sovereign with the 8T coil will separate targets better with a greater depth than the Fisher with the sniper coil..
Crazyman,I have used two Sunray S-8 coils one with a short cable and a long cable coil.I have done an air test comparison with these coils. The small Tornado was the best of these two and would give a solid zing about an inch out further than the S-8 Sunray.The Tornado 800 also seemed to give a faster and stronger response on deeper targets in the field.I did like the S-8 better than the 8 inch Coinsearch.I think the S-8 8" is a great coil but the smaller Minelab Tornado 800 7.25" is the best in this category.
The response and tones of the S-8 seem to be somewhere between my 8 inch Coinsearch and my 10 inch Tornado. Not as wide and drawn out as the Coinsearch but not as sharp and distinct as the Tornado. I'm able to distinguish to tones better with the Tornado so I'll have to pick up a 7 1/4 inch Tornado.
Crazyman,your description between the three coils is the exact way I see the differences,The Tornado 800 is even more sharp than the Tornado 1000 and easier to hunt with but not as much depth as the 10 inch coil.By the way where is DFX Hollywood Greg? I think I got him beat! I was just told to put in casting photos of myself and Jake my horse for a movie being made hear in Michigan by Steven Spielburg coming out in 2011 Real Steel.Probably a Gabbie Hayes Double LOL.Later Ron
Ron,
I find myself in more trashy area's than not .....How much deeper is the Tornado 1000 than the 800 ? ...... I deal with a double edged sword ...I need the depth to go after the Silver that I find in the parks that I frequent which is where the 1000 will shine, but also need the seperation that I'm sure the 800 will better afford me ......Thanks, Jim
I find myself in more trashy area's than not .....How much deeper is the Tornado 1000 than the 800 ? ...... I deal with a double edged sword ...I need the depth to go after the Silver that I find in the parks that I frequent which is where the 1000 will shine, but also need the seperation that I'm sure the 800 will better afford me ......Thanks, Jim
Critterhunter
New member
So far I really like the S-5 being 5.5" for about as good of separation as it's going to get, but the depth is about 7" or so in air testing at max sensitivity. Probably deeper in the ground. From the sound of it the 8" coil has a good 2" of depth advantage and separates very good as well.
The difference in DD and concentrics is that a DD of the same size will see less ground minerals. It's detection line from tip to toe is thin, where as a concentric has more of a wide/round egg shaped signal which as a result will see more ground matrix and thus not handle rough ground as well. A concentric's most useful separation comes at it's fringes of depth where the signal is smallest, where as a DD has good separation for the most part at any depth. You just have to learn to work a DD to separate targets differently than a concentric. You need to move around the target to a point where the detection line is going over the desired target but is not also crossing the trash. The thin line will allow you to separate the two targets better than the concentric provided you do that, and as said a concentric wouldn't have any advantage except at it's deepest point, and might still not separate as well. I was always a believer in concentrics doing a better job in trash until I read more on the subject and learned how to use a DD properly. Now I know the reverse is for sure true.
Another advantage to a DD is that they tend to be more sensitive to smaller targets than a concentric, and this is most apparent once coil sizes get past say 10 or 11" in size. For that reason a 12" concentric is really pushing it as far as depth and sensitivity to coin sized targets, where as many believe a DD can get as big as 14 or 15" in size and still retain good sensitivity to coin sized targets at depth and even smaller targets where as a concentric in this size range would be considered only use for larger items like cache hunting by many.
The difference in DD and concentrics is that a DD of the same size will see less ground minerals. It's detection line from tip to toe is thin, where as a concentric has more of a wide/round egg shaped signal which as a result will see more ground matrix and thus not handle rough ground as well. A concentric's most useful separation comes at it's fringes of depth where the signal is smallest, where as a DD has good separation for the most part at any depth. You just have to learn to work a DD to separate targets differently than a concentric. You need to move around the target to a point where the detection line is going over the desired target but is not also crossing the trash. The thin line will allow you to separate the two targets better than the concentric provided you do that, and as said a concentric wouldn't have any advantage except at it's deepest point, and might still not separate as well. I was always a believer in concentrics doing a better job in trash until I read more on the subject and learned how to use a DD properly. Now I know the reverse is for sure true.
Another advantage to a DD is that they tend to be more sensitive to smaller targets than a concentric, and this is most apparent once coil sizes get past say 10 or 11" in size. For that reason a 12" concentric is really pushing it as far as depth and sensitivity to coin sized targets, where as many believe a DD can get as big as 14 or 15" in size and still retain good sensitivity to coin sized targets at depth and even smaller targets where as a concentric in this size range would be considered only use for larger items like cache hunting by many.
Jim,I have found silver and wheat's with the Tornado 800 that on a cross check my friend's V3 could not detect as a good target.No problem to find coins up to nine inches with this small coil.The separation of this coil is excellent and its very stable.No coil is perfect,but is probably the best compromise you will find.The Slimline 1000 is probably 2- 3 inches deeper with work to lock on those faint targets. Buy a T 800 used at a good price and you will always get your money back.