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GPZ 10" Xcoils In USA


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Thanks Chet. In my mind you are like having an American JP around the forum, except unbound by non-disclosure agreements. I appreciate your contributions and the technical explainations, I love that stuff. 

Also appreciate the original JP too! Nice to have both of you contributing technical stuff. ?

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Andy, as promised here is a visualization of what I'm hearing (not to scale, my photoshop skills suck), the detection field of the coil. As those detection fields get more and more smooshed out its feels more and more "mono-like" (while obviously still not being a mono). This is only looking at the part of the coil the RX overlaps the TX (the two "blades").

It just feels like the detection field is broader to me on these so far. Maybe the spiral more than the bundle, I'll have to check.

1705152732_detectionfield.jpg.aabbf264dbc1a1f582c806e13dde4dda.jpg

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Thanks for clarifying, Jason.  In the future I will have to pay more attention to the sound pattern.  But what you are saying makes sense now. If the signal is wider, you would be able to detect more nuggets up on the edge of the coil deeper.  This could lead to an advantage if this is the case. 

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You`ll notice the X coils acting like monos, is real pronounced when you are centering the target in a hole you`ll find all the coil edges are responsive equally with coil standing vertical plus you can drop the handful of soil with the nugget in, to retrieve  on any part of the top surface of the coil that I suspect is as Chet has suggested got to do with those transmit & receive coils not being separated as per the ML coils. Just some further advantages to add to the extra sensitivity & depth the X coils have over the ML coils. Of course this is my opinion, I am just loving the extra zing these coils have given to the magic Z.

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16 hours ago, Chet said:

The lowering the X-Coil transmit coil approximately 2cm/0.75” creates an exponentially greater target signal return to the receiver coils. 

DOD receiver coils are wired in series (voltage adding) so that with a large target the returned signals are combined effectively into one centered search lobe similar to a Mono coil.

A very small shallow/weak target normally does not return enough signal strength to both receive coils to be formed into a Mono like search lobe. Thus they are predominantly detected in the more sensitive areas near the windings. 

The lowering of the X-Coil transmit coil approximately 2cm/0.75” creates exponentially greater signal strength from a small target.  This can produce enough signal from some small targets into both receive coils to provide a Mono coil like search lobe. This will be most evident with smaller coils that concentrate the transmit energy into a smaller area.

So the lower transmit coil hurts us in some cases where the ground is saturated with surface ground signal but helps us on ground that is not saturated.  Interesting.

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Interesting for sure, now as we gain some understanding of the X coils different construction it is explaining the very obvious increase in performance operators have reported on. I certainly have experienced this in the field and suspect now as the hours of use are accumulating, the spiral wound coils are illustrating this more so. Chet thank you for pointing out the pros of having the transmit and receive coils closer. Always when you are using a new coil in the field you wonder if what you think may be improved performance could be just a placebo effect, at first but with time it becomes obvious.

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11 hours ago, davsgold said:

I noticed the X-Coils also being "Mono Like" without actually being mono coils.  Over 12 months ago now when I first used the original 18" prototype standard (bundle) wound coil (X-Coil) well it didn't even have a name back then.  One of the first things I noticed and commented about was it being similar to a Mono in it' target response and to outer edge being much more sensitive.

I found the target signals starting to be picked up as the coil approached the target and get increasing loud as the coil passed over the target.  When compared to the GPZ14 coil this was a nice surprise as well.

cheers dave

 

Is this a Spiral wound coil your talking about Dave or traditional wound DoD? The Spiral wound coils have the Tx spread out really wide and I’d say the Tx is then influencing the Rx during receive.

 

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1 hour ago, davsgold said:

I first noticed it the first time I used the 18" prototype over one year ago, and this was the only coil in Australia at the time, and was a traditional type "DoD" and the later coils also seem to posses this characteristic also, and the spiral wound coils which came along sometime later seem to also work in a similar manner with Mono like properties without being a mono coil.  This is just what I have noticed.

regards dave 

Then it must be to do with the spacing between the windings, its hard to determine this here in Clermont because the ground is so Variable. I’ll ask Al when we next catch up. Will explain some of the saturation issues and also why some gold modes behave differently compared to others.

 

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UPDATE: (SDC small gold comparison)

Ok, I didn't want to start yet another Xcoil thread so I am just adding to this one.

Be forewarned, if you are only a big game gold hunter, finding grams and ounces at a time, and then throwing the little guys over your shoulder in disgust, you will not be interested in this report.  This is mainly for those of us who creep in the shadows picking up little bits here and there, to keep down the gold fever.  A little piece of gold Xanax if you will.  We call it crumbing here in the states. It is a highly technical term I prefer not to waste time reviewing. :cool:  It is just big enough for us to take a picture with our smart phones and blow it up big enough to look awesome on our screen savers.  (blown up 100x)

So the bad news is I was not able to do a direct comparison with the SDC, but I was able to get some input on average gold depths for small gold.  Then I took those numbers and went to the gold fields for some testing.  Results were interesting and a little surprising.   But let me preface my data table as, this data was taken at my conditions, my settings.  Some will get better depth and some will get worse.  So don't flame me for just sharing data I found.  It is just so people have a very rough idea of where the 10" Xcoil might relate to the SDC 2300.

Settings were what I use for small gold.  Sens=8,Vol=13,Thresh=27, High Smoothing, Manual Ground Balance (after setting to ferrite)  Similar to Lunk's Settings discussed a while back.

1797391069_DeptEstimates.thumb.JPG.91b7c5258aa3b893a4308077dd2f6e25.JPG

As you can see, I picked four very small nuggets.  Since the SDC is known for the .1 gram range, I focused on this and smaller.  The SDC averages are just that, averages.  They are approximations.   But they are from a very experienced operator that I respect, so I do assume they are good for a rough estimate.

I will let you make your own judgements but I will say a couple things.  Firstly, I was a little surprised the 14" coil was decently close to the SDC.  The 14" coil size is definitely all that is holding it back.  Secondly, as I had expected previously, I usually got an extra 1.5" or more on some of my nuggets by using the 10" coil.  This explains why I was able to go back to my first patch (previously discussed) that was gridded and easily pick up more in the .1 gram range.  There does seem to be an advantage in the smaller flakes.  I was also very surprised that the 10" coil could get a piece nearly a half grain at almost 2 inches.  Typically, I would have to be nearly on it.

So based on these rough and I stress the words "rough" estimation, the 10" Xcoil may be a good substitute for those not wanting to pay for an SDC and willing to take on a science project.  This was my original reason for getting it, to compare to the SDC.  I will be curious to see what others find when doing direct comparisons.

Also, If I am to extrapolate data, I would predict that the two coils (14" and 10") even out at about the .5gram size for depth and then as the gold gets bigger, the 14x13 will likely rule this camp altogether. 

Again, this is nothing definite, but even if my data is half accurate, it does show that the 10" Xcoil puts us very close to what the SDC can do.  And that is a good thing to know.

 

 

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You are a brave soul, Andyy...thanks for the info. Coil discussions tend to go on and on and on...

I appreciate the effort to get these approximations-the process is way too boring for me.

The Russian X coils have livened up my reading, thank you MR. Russia.

If I wanted one I would not be jumping in until the whole connection issue is solved. I had to repair one broken wire on a DD commander coil...what a pain!

And, the price is way too much for me to spend at this point in my detecting life...

please keep us informed

fred

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