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Under 4 Pound, Under $2000 Gbpi Challenge


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Steve

 I agree with you on what i'd run with. Like said if the GM 1000 can't handle the hot ground I may just have to move over a short ways. We all know that the ground we hunt will change from time too time. Just maybe more than we realize.

Chuck

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Back when I did the battery tests on the TDI SL the overall average run time I got was 6 hrs 20 mins using 2650 mah batteries and the 9 cell conversion did not add to the run time but it did bump up the voltage to over well over 12 volts, making it a bit more sparky but no real depth increase but the signals were more positive,

One thing I noticed during testing is that the SL does not work like the TDI Pro when you turn off the GB and you gain a depth boost, In fact the SL is the reverse where the SL gains depth with the GB "ON", over the time I have owned the SL and the MXT 99% of the time I will try and use the MXT because in the All Metal mode it will match the SL and when fitted with the 12/300 coil or the 14x10 it will out run it for all out depth,

Don't get me wrong because the SL is a great little machine but my biggest grudge with the SL is not so much the depth / power but it's lack of sensitivity to small bits which to me is the biggest problem because the smallest bit of metal/Lead I have found with it is 0.17 grams and yet with the standard MXT 10" DD coil I found bits weighing 0.06 and 0.03 grams and when I switched out the coil to the 5.3 eclipse coil it found a bit weighing 0.006 grams, So because of the MXT's sensitivity I will always pick it over the SL even if the ground does Hot up because even running a reduced Gain due to ground conditions the MXT can still see smaller surface bits, And even fitting the factory 7.5 DF Mono to the SL had Zero effect on it's seeing abilities and the only gain in using the 7.5 coil is that it fits in to tighter areas.

EDIT:- by fitting one of Miner Johns folded Mono Coils will boost the TDI SL's abilities to see much smaller Bits / items than the factory Coils,

On the beach the SL is a great all rounder and in bad ground with hot rocks and serpentine it really excels, But it's abilities to ignore EMI is a major leap forward compared to all other PI's, It will run flat out in the middle of the city and It will run smooth even with Thunder storms going over head where other PI's will warble away if a storm is within 200 miles or more,  "I know" because when we had real bad thunder storms here one night I tried it and the MXT would not run about 6 or 7 without very bad spikes in the EMI blasting out the speaker, and because of this I see the SL as a secrete weapon to have when conditions are such that other machines will cause you to pack up and go home, So this alone Is one reason why people should own the TDI SL, It is far from perfect but it can make the difference in whether a person can go detecting or not.

 

Hope this helps.

John.  

 

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6 hours ago, auminesweeper said:

Don't get me wrong because the SL is a great little machine but my biggest grudge with the SL is not so much the depth / power but it's lack of sensitivity to small bits which to me is the biggest problem because the smallest bit of metal/Lead I have found with it is 0.17 grams and yet with the standard MXT 10" DD coil I found bits weighing 0.06 and 0.03 grams and when I switched out the coil to the 5.3 eclipse coil it found a bit weighing 0.006 grams

While in Arizona this past February I found two tiny non-ferrous pieces with the TDI/SPP and had to buy a new scale to weight them.  I was hoping to be able to do a decent specific gravity (density) determination using Archimedes Principle but even the new scale couldn't do that very well.  The masses were 0.047 g and 0.058 g and they looked like copper under my strongest magnifier.  (On my 'to buy' list is a stereo reflecting microscope.)  Getting off on a tangent (I'm good at that...), 'g' means grams just about everywhere in the world.  I think grains are abbreviated gr.  I found out that this new scale (1 milligram = 1 mg = 0.001 g precision) is difficult to use because just about anything will give a force in the milligram range.  I had a chance to buy a Mettler Balance in an antique store with even higher precision (factor of 10 smaller) one time and balked.  I think it was about $10!  Been kicking myself since I got back into detecting.  :sad:

I took two coils on that trip -- 3"x6" prototype and 5"x9" Miner John folded mono.  I know I found one of the pieces with the smaller coil.  I thought I found the other with the MJ, but not sure about that.  I also don't know the depth since in both cases I used my pick to loosen the soil and then scooped through the loose stuff until I found them.  But I strongly doubt they were anything deeper than an inch.

Still, your 0.003 g with the MXT has my pieces beat by an order of magnitude.

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That's impressive, I only have the factory coils for my SL so alas my lack of success, But I would really like some hot coils for it because with the standard coils I am sure I am missing a lot of real small targets because I think that the factory DF coils are more aimed at Relic hunting than prospecting,

The symbol for Grains  should be "Gn" and Gr or "G" ( g ) is normally the symbol for "Grams"

I had to buy a set of Scales with a 5/6 digit readout for weighing smaller bits that can weigh things to as low as 0.0001oz and 0.001g (grams), I did the ebay thing but after about a month of being sent scales that were either not as described or had the wrong measurements on them I had to go to a Real Scale retailers in order to buy a set that are certified and calibrated,.

Thanks for the Info that's very helpful,

John.

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John, did you see this thread?

In particular on page 2, AussieMatt links to an exhaustive study done in Australia, both air tests and in-ground tests of about a dozen coils for the TDI.  (This was done with one of the big-box TDI's.)  Based on that I've since bought a (used) NuggetFinder Sadie and my early tests confirm it is great.  I have data which I'm going to post there to add to / enhance what has been done, but mine so far are only in-air tests which everyone knows have their limitations.

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Thanks for that, I saw it when they first started to test them but I never saw the out come, I don't under stand how they got the TDI Pro with a 12" DF to see such small things, Maybe it was because the nugget was long and Flat because mine won't see them in their natural state and neither would the 7.5 DF coil, I ran both my TDI SL and the TDI Pro maxed out and it just could not see them even when they are sitting on the Coils, So the results of TDI being able to see that test nugget is because it is long and flat,  I need to find a NF Sadie or the new Coiltek TDI Series or both,

I really would like to use the TDI SL more, As pointed out it is nice and light and a joy to use and I think with better coils the SL could be as good as it was meant to be,

Thanks again,

John.

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I have to admit I am getting extremely frustrated that no detector company is up to this challenge. I posted this nearly two years ago now and still no ground balancing PI detectors under 4 lbs, under $2K with the exception of the White's TDI models.

whites-tdi-sl-special-edition.jpg
White's TDI SL Special Edition

 

There is the new Fisher Impulse AQ on the way soon, but the first version is a beach detector. It may or may not develop into a good dry land unit.

It's all particularly maddening because I am perfectly satisfied with the performance of the Garrett ATX circuit. I simply want the electronics in a dry land design with simple dry land coils. It's an easy project, but Garrett is steadfastly not doing it. I honestly just don't get it. The machine I want would blow away ATX unit sales and with a lower production costs no reason margins would take a hit. Garrett is generally smarter than this so it is a puzzle.

And where is Nokta/Makro?

Like I said.... frustrated.

If I ignore my under 4 lb under $2K criteria, what machine in my opinion gets the closest? That would be the Minelab GPX 4500. The battery is put on a harness and so the actual detector "weight on arm" is 5.3 lbs and you can get them brand new for $2699 or less. I just can't bring myself to go with the TDI SL because it lacks the horsepower and so if I personally had to get a GBPI detector tomorrow and wanted to get as close as possible to my under 4 lb under $2K detector I would have to settle for the GPX 4500 as being as close as I could get without shooting myself in the foot.

minelab-gpx-4500-pulse-induction-pi-gold
Minelab GPX 4500

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I was really hoping that the challenge you had posted would be met as well; I've held off from any major detector purchase for years thinking that what you asked for would likely be right around the corner. The SDC, my primary detector, is close but again utilized a military framework inducing extraneous bulk, and lacks the depth of the said ATX circuit. It's not like you set an unattainable bar - any of the major companies could produce a detector meeting the criteria. ☹️

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2 hours ago, Steve Herschbach said:

It's all particularly maddening because I am perfectly satisfied with the performance of the Garrett ATX circuit. I simply want the electronics in a dry land design with simple dry land coils. It's an easy project, but Garrett is steadfastly not doing it. I honestly just don't get it. The machine I want would blow away ATX unit sales and with a lower production cost no reason margin would take a hit. Garrett is generally smarter than this so it is a puzzle.

I'm still kicking myself for not bidding on the ATX you modified and ended up selling on Ebay (with multiple coils) for ~$1k.

I hope we're not seeing at Garrett what happens way too often (e.g. Tesoro) where a business is handed down to the next generation and subsequently run into the ground.  Charles Garrett wasn't your typical detector designer/manufacturer/marketer, but still.  His son had plenty of years to learn.  Maybe he'll surprise us yet, but so far I'm not impressed.

I've been hopeful that First Texas would step up, given all their design and engineering experience, including Carl Moreland who played a major roll in the White's TDI line.  And let's not forget that Minelab, who has held such a stranglehold on the PI market, is certainly capable of making lightweight, affordable detectors as they proved with the Equinox.

Steve, there are a lot of us who share your frustration.

 

 

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