Here's something I've never seen mentioned..........

[Ivan]

A fellow TH'er contacted me after he read one of my recent postings. It was the ("Have to rethink the 8" coil" ) . He decided to go to the Teknetics 8" round coil on his Omega for exclusive use. He explained that as he was retired.... he usually hunts between 4 to 6 hours a day 5 or 6 days per week. That's alot of hours. His first observation was that with the 8" coil the Omega was far lighter and had less wrist fatigue than with his white soild 10 DD coil. He also had lots of experience with the stock 10" concnetric as well. The weird thing was that he swears that the round coil is finding more "round" targets. So far 3 gold rings and 4 silver rings, 2 larger sized circular pendents/charms.... and lots of washers...key chain rings etc. He's convinced that with his eliptical coils he has never found as many "roundish" targets. As I'm quite new to the Omega I really don't know?? Hopefully an Omega expert like Monte will chime in. But I throw out this question out to everybody, is it possible that round coils hit round targets with greater regularity??? What do you guys say? Is there any merit to this theory? Thanks for your feedback.

 

[supertraq]

I guess i'm a little differant in that i fell the 10" concentric works better in trashy ground and is deeper,i also have a nel sharpshooter and i like the 10" concentric more,its deeper than the nel and works just as good in the trash..
Maybe i need to try the 8" doughnut again? s.t

 

[Ivan]

Let's not get side tracked................the issue is not depth or how well a coil works.......but rather it's ability to find more "round targets". This is obviously a tough question..............in my hunts next year I plan to alternate use of the different coils and I will log the number of round targets per hunt by coil. I guess over time a picture may develop.We'll see how things work out.It is an interesting question!!!

 

[detectingMO]

round coil is the best at IDing targets and the omega programming sure loves to hit hard on round objects. Perhaps it's not necessarily round coil = round objects but rather round coil = better ID = more round objects.

 

[Monte]

some of the benefits of using a particular shape and type of search coil. Matter of fact, I'll even point a finger at me as being one of the 'regular' characters who make references to using ROUND and CONCENTRIC type search coils whenever I can.

A fellow TH'er contacted me after he read one of my recent postings. It was the ("Have to rethink the 8" coil" ) . He decided to go to the Teknetics 8" round coil on his Omega for exclusive use.

Let me clarify for readers that here we are referring to a ROUND shaped search coil about 8" in diameter, and it is a CONCENTRIC designed search coil, not a Double-D type [size=small](and from different manufacturers a DD coil can be elliptical or round)[/size]. I like the stock elliptical 10" coil on the Omega, which is a Concentric design. However, long ago after experimenting with the Round 8" Concentric from a Delta, I knew it would be easier to quickly Pinpoint a target than the elliptical 10", but I found that it just worked better, all-around. It did better in general day-to-day hunting, worked many trashy sites better, handled some iron trash a little better, and just 'felt' better to use. I also preferred it to the 5X110 elliptical Double-D coil.

He explained that as he was retired.... he usually hunts between 4 to 6 hours a day 5 or 6 days per week. That's alot of hours.

Back in the early days when I was not just a super-enthused detectorist but also younger and more able to move and endure a lot of swing-time, I worked, but still tried to get 2 to 6 hours in a day, on work days. Weather permitting it could be 6 hours to a full-day on my days off. Today, after being disabled for 23+ years and retied for the past 4½, I try to get in all the hunting time I can, The big problem now is terrible health limitation that cut into the time I can spend w/o taking a break.

We all need to figure out when and how much time we can budget to 'having fun' and then get out and commit to it.

His first observation was that with the 8" coil the Omega was far lighter and had less wrist fatigue than with his white soild 10 DD coil. He also had lots of experience with the stock 10" concnetric as well.

The 8" coil balances nicely, doesn't cause fatigue, and I can also hunt longer or not tire as quickly with it as I do with the other coils. Part of that is because the other coils just don't have the same qualities in performance as the 8" round Concentric coil. That calls for a bit more re-sweeping to check a target, or even to find a target.

The weird thing was that he swears that the round coil is finding more "round" targets. So far 3 gold rings and 4 silver rings, 2 larger sized circular pendents/charms.... and lots of washers...key chain rings etc.

I know that, as detecting MO said, I just tend to find more targets, round or otherwise.

He's convinced that with his eliptical coils he has never found as many "roundish" targets.

I think they did, or could have, find as many roundish targets, but due to the shape of the windings, especially with the Double-D configuration, you usually won't get audio hits or visual TID/VDI 'lock-ons' as cleanly as with the elliptical Concentric or Double-D coils.

As I'm quite new to the Omega I really don't know?? Hopefully an Omega expert like Monte will chime in.

I chimed in, and all I can say is each of us needs to try a variety of search coil sizes and in different hunting environments to know what works best for us. In my case, I wish FTP made about a 5½"-6½" CONCENTRIC search coil as I favor smaller-than-stock coil for the trashier and brushier sites I usually hunt.

Because they don't, and after working with all of the Tek. coils available, I have my two favorite search coils to own and use. Those are the ROUND 8" Concentric coil for most general, open area/low-target sites, and the ROUND sub-5" Double-D coil to help in the densest of trash conditions.

But I throw out this question out to everybody, is it possible that round coils hit round targets with greater regularity??? What do you guys say? Is there any merit to this theory?

Yes, there could be some steps to 'prove' a slight edge, but rather than tinker with experiments I think it's just best to use a coil enough to learn its strengths and weaknesses, then select the one we desire to use the most, then hunt away.

Monte

 

[Hightone]

I don't see how round or square would matter in detecting. The detector reads the conductivity of the metal, not the shape.

 

[Dave J.]

Ever dig a steel bottlecap? That round shape is a killer. Take the bottlecap and hammer it into a crumpled lump. Whole different animal.

 

[BarryL]

Ever dig a steel bottlecap? That round shape is a killer. Take the bottlecap and hammer it into a crumpled lump. Whole different animal.

I have took one and folded it half and re buried it and yes totally different signal with My Shadow X2 it spits and breaks from the typical solid coin signal I agree with Dave J

 

[Hightone]

I guess shape has some relevance. Some square tabs show up as round nickels. Are you saying a round 8" coil can distinguish the nickel over the tab better than the elliptical or DD coils because the round coil matches the round coin? Maybe I'm using the wrong coil.

 

[Hightone]

I think Ivan is saying that his friend finds more round coins, more round rings, because he uses a round coil rather than an elliptical concentric. I'm trying to see the logic in it. If it's true, I need to just use a round coil, as all I hunt is coins and jewelry. My LRP came with a 11" DD elliptical and my QDP came with a 10" concentric elliptical. If I put a 8" round on my detectors do I increase the chance of finding rings and coins?

 

[Dave J.]

I think Ivan is saying that his friend finds more round coins, more round rings, because he uses a round coil rather than an elliptical concentric. I'm trying to see the logic in it. If it's true, I need to just use a round coil, as all I hunt is coins and jewelry. My LRP came with a 11" DD elliptical and my QDP came with a 10" concentric elliptical. If I put a 8" round on my detectors do I increase the chance of finding rings and coins?

Your original comment that the machine responds to "conductivity" was partly true, and before "motion discrimination" it was mostly true. When the searchcoil passes over the target, the phase response depends on the apparent conductivity, which is a function of the material specific conductivity, the amount of the stuff, and its shape. As far as the searchcoil is concerned, the shape of the target changes as you sweep across the target, since it's looking at the target from a different angle.

Even back in the heyday of TR/Disc before motion discrimination took over, it was widely recognized that targets looked different to DD's than to concentrics. And that DD's, which had a reputation for seeing through ground minerals better, had a harder time discriminating out iron.

When motion disc really took off in the early 1980's, the same problem cropped up: better rejection of the iron minerals in the ground, at the cost of poorer iron rejection. The combination of DD's with motion disc was at that time regarded as a fatal combination, and DD's fell into disfavor.

Over time, especially with the use of microcomputers to crunch the data, motion discrimination improved in most respects while falling short in others. One of the things that improved, was tolerance for the response characteristics of DD searchcoils. Meanwhile the steel bottlecaps generally got worse.

And that's where the state of the art is today. We've got stuff under development that takes it farther, but for obvious reasons I can't say just what it will be or when it will hit the market.

In my opinion, in general, concentrics will do better on the shallower stuff and DD's will do better on the deeper stuff. The reason I say "in my opinion, in general" is because there is no one "correct answer". Depends on what targets under what field conditions and how the user uses the machine and interprets its responses.

So back to the "round vs. elliptical" thing: I don't support a theory that round searchcoils do better on round targets than do ellipticals. Given a choice, I always prefer elliptical, regardless of whether it's DD or concentric. And in general, I prefer DD. Those are personal preferences, and you can see in this thread that there are competent users whose preferences differ from mine.

 

[Hightone]

It all coincides with your article on "search coil shapes". An absolute astronomical amount parameters and variables that you have to consider. Not as cut and dry as one would believe. Thanks for the clarification.

 

[mudpuppy]

I love the mental gymnastics that take place when a guy is infield behind the coil!

I surely will not argue with your friends experience or thought process, Ivan...I have been operating under the assumption from seeing diagrams, and a bit of time afield that a concentric threw an inverted cone type of pulse, and a DD throws out a 'paint brush' rectangular pass that is sort of shaped like a 'U' instead of a 'V'...saying that the 'U' signal gives a wider pass, and gets stronger as the target is centered beneath the sweet spot...

I will say this, on all targets, a guy can 'hop' coil or tap it like a drummer with a DD over a bottle cap, (Q) with great success..even a P stacked on top of a Q sounds tight, whereas a bottle cap washes right out....the Q stays solid and the bottle cap washes out...I figure the vertical signal shooting straight down has an effect in the fast recovery circuitry or something...anyway, as Dave said, I would believe its really how much time you spend learning the language of the total package and what a guy gets comfortable and CONFIDENT in using...with a normal side to side swing, even a wiggle, a rusty flattened bottlecap can sound exactly like a Q...that is if a guy really WANTS it to sound like a Q...tapping DD coil on top of the target eliminates this confusion immediately, probably because what Dave mentioned, as a coil sweeps ACROSS a target, its shape changes..but when pumped up and down very briskly with a DD...the shape does NOT change, but the rig gets a better feel of the composition? Distinguishing iron from clad/silver? I dont know why, but it works for me..When running a DD, a guy will hear a tiny chirp of a target that was on the outermost edge of the 'paint brush' and then can quickly zero in on it with corresponding tight passes and then the tap to center and furthur ID the composition...

My mental musings and experience afield lead me to believe theres things to be learned about alternative coil manipulation techniques instead of the traditional side to side swing and wiggle...a guy can hop coil, never ever use the PP feature again...and center a good target right under the sweet spot, and leave the caps in the ground.. If I ever figure out how this works on gold rings, I'll surely do a post...nickels hold really tight tapping coil too.. depending upon target depth, the TID may change, but the tones do not....Oh, I run an F70 with 11"dd...DP tones, very fast and light...
Mud