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Jin

How Deep Do Today's Detectors Go Compared To Older Technology?

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I was reading the Australian Electronic Gold Prospecting Forum today and noticed a post about detector depth. I was wondering what others think about today's detectors compared to what was available 25 years ago. I read somewhere that (Woody) the guy that does mods to detectors thinks that for outright depth the sd2000 still goes the deepest. I wouldn't know as I've never owned a sd2000 or a gpz7000. Anyway, i found the comments at AEGPF interesting and wonder if anyone here has actually done a depth comparison between the zed and sd2000. Heres the snippet from AEGPF 

Quote from AEGPF: "The deepest Pi detector ever developed in my opinion was a prototype  SD2000  that BC modified for the late Jim Stewart.BC slowed down the clock speed to give a very long pulse and made some other unknown changes to the circuit to cope with higher currents etc. At the time the SD2000 came out BC stated that it was at about 95% of the maximum potential depth that any handheld PI could ever achieve (and still pass emission standards). However, the deepest PI that has ever been made for gold was Corybns detector which detected a  nugget of around 10oz? at 3 feet in depth in WA. Somewhere on the forum is a reference to it and I will try and find the link when I have time.

"What is interesting is that the deepest nuggets ever detected by a Pi  was by a detector used in the early 1980's in WA-Corbyn's  wheeled detector! Pictures of it  and the depths of some of nuggets he found with it can be seen in Mike Wattones book: Quest for gold.NO Pi detector today could match the depths Corby got on at least one nugget! (4cm nugget at over 36" in mineralized ground)"

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Well jin, no takers on this subject. I have a few clues, but not sure I should post them, as it could stir up a hornets nest.

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My though is that PI detectors in the 2000 series, both mod'ed and standard, were a steady progression of improvements in sensitivity, ground balance and depth.  The 2000 was the most modified of the series and as the base model it was the most accepting of tinkering for outright depth.  However it suffered for sensitivity.  Could not have one for the other.  With the advent of the GP, GPX series the transition to digital processing has made greater depth with sensitivity to smaller targets that the 2000 series can not accomplish due to analog design restrictions.  As to outright power the 2000 has it, thru modification, but it simply cant perform as the later GP series can. There is no need to put the GPZ into this thought as its a different system altogether.  My thoughts.

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Some of the results we see only happen when all the planets align and can not be repeated on a target to target bases, I have achieved extreme depths with both PI's and VLF's but I have never had either of them do it on demand,  The deepest small target I found was with the sovereign GT with a standard coil, Yet my 3500 with the 11"DD could not see it, Move on 10 years I found the Iron subway tunnel supports with my TDI SL at over 6 feet deep using the standard 12" DF coil,

Neither machine was/is outstanding on a daily bases but some targets seem to do the impossible when you lest expect it, The down side of that is that it give you false hope because just because they do it once or twice does not mean that is what is happening under the coil all the time,

I have air tested my machines till the cows come home and in doing so I except that I am getting 30% of that depth on a daily bases and anything deeper is a bonus, the real depth is a bit deeper but to avoid disappointment I set my expectations low, using this as a base line I look at the ground and think "Coils" as in do I go large and drop the sensitivity or do I use a smaller coil and crank it up, Knowing how deep the soil is in relation to the sub base has a lot to do with my coil selection, there is no point in using a big coil if the soil is only 10" deep, I tend to look at the ground as layers depending if I am coin shooting /relic hunting, If I can get down to the sub base on a few targets then I know I am not leaving much behind, but If I am trying to find Gold then coil selection to ground depth is a lot more critical that's when I start to second guess things, Sometimes it has worked and a lot of times it has not, this is another reason why I stopped chopping and changing machines, As point out we reached the max depth back in the 90's, My old 5900 is an 1989 model and it is the deepest VLF I have ever seen,

J.  

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I agree with Steve, the VLF's have plateau'd yrs ago on depth, my current experience with them is they are great for surface tiny gold 1-5 grains to maybe 3-4" max. We have to face it we are hunting mostly well flogged known gold areas now days and all that is left to find is 1-5 grain size nuggets, and extremely deep, 10" to 17"  deep, 1/2 gram to 3 gram nuggets missed by the earlier sd and gp machines. The GPZ is doing a bang up job on the 1/2 gm-3 gm size nuggets to depths its hard to believe, it seems they get around 3"-4" more depth on gram size gold than my 4500, from actual observation of digs.  The pi's like the gpx 4500-5000 are still a viable machine to use with the new tech flat wound coils, but not so much with stock coils. Hopefully there is more new tech machines available in the near future with the ability to find this type gold.

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I've probably stated this before, but the prototype PI seemed to have the most 'boogy' of any detector I've used.

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That would not surprise me Reg. Prototypes were often ungainly analog monstrosities from a retail standpoint, but they sometimes lose something in the translation from wild eyed prototype to well behaved retail product.

I will still bet every time on people who have top notch research and prospecting skills first. Asking which detector they use comes second. I like my detectors but frankly I don't see why they get so much credit in finding stuff. Consistently successful prospectors generally go from one machine to another and stay successful. People who don't take care of research and basic prospecting skills - well, half the time it does not matter what detector they use or if they use a detector at all. Bet on the prospector, not the machine.

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Having spent a few months this past year testing coils for my VLF I think the company who can get a VLF to put all that wasted power in to the ground will turn the detecting world on it's head,

One Coil I regret not buying sooner is my Detech Excellertor 14x10,  I was going to buy one back when they came out and the dealer said they were **** so that was the end of that, Now I have one it has become my must have coil for a couple of reasons 1) it is the same weight as my factory 10"DD, 2) it has the depth of the 12" Concentric and 3) being a DD it does not loose much depth compare to the 12"c. and 4) the size of it covers just the right amount of ground in open areas, 5) and it can see bits down to 0.03 grams on the surface.

During testing I was digging a hole using my pick and I kept hearing what I thought was faint EMI and every time I stopped digging the noise stopped then I realized it was signalling on me swinging the pick, I always point the detector away from where I am digging, anyways I measured how far the coil was from the hole and my pick is like an Aussie Walco Pick but the blade is only 10x3" and this coil was seeing it at a measured 5 feet away.

It is only a matter of time before this coil finds a deep target but when it does I hope it is a life changer,

J.

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For me the PIs I`ve used topped out in sensitivity , depth and smoothness with the 5000, the GPZ has gone another step and increases that sensitivity, depth and smoothness again. These gains prove themselves over and over when I wander back to old patches. I believe these gains were made in the PIs with better capability to handle ground conditions through GB refinements and timings. The SDC illustrates this, I believe that has a lot to do with its single coil and it being "paired" to it electronically.

The Z has shown to me conclusively this is where it shines, its auto ground balance seldom gets it wrong if you get a persistent signal although very weak as you swing over the target a few times you can almost bet it is metal. I found I can trust the auto GB on the Z over the PIs(other then the SDC) this has lead to covering more area each day thus increasing production, this is especially so when patch hunting.

I`ve included the Z in my post because the thread is about depth comparison, between detectors. To me the Z has proven beyond doubt of the detectors I`ve used it ticks this box out there in the field where it counts, for me the 5000 comes a close second. I must state I take the replaced detector out into the field usually only once with the upgraded new detector, I am not into testing detectors rather I let their production prove them up.

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