Explorer versus small gold (bracelets,necklaces)

[Anonymous]

Hello again,
What success have you Explorer users had in detecting small gold (ankle chains, bracelets, necklaces etc)? I have heard that it is extremely difficult to detect such items.
I tried an air test with my Garrett GTI 2500 on a small gold necklace and it was the pitts. In jewelry mode (discriminate) it would not pick it up at all. In all metal mode, I had to be within at least an inch before it would pick it up. And, even then, the audio response was very, very weak.
I understand that most detectors work on the surface area of an object. Therefore knowing, that a necklace would not have much surface area (unless balled up). But, could it be, that my Garrett is just geared up for "stuff" that is on the high end of the conductivity range???
I have heard that it is very hard to find small gold necklaces and the like with any detector. But, am just curious if the Explorer may be hotter on gold and maybe set up more toward the medium end of the conductivity range where gold would be picked up easier?????????
I'm just trying to get a "handle" on a few things before my Explorer arrives. Which I hope will be on Friday.
Mike

 

[Anonymous]

I have a 6" roll of silver solder, about 20 wraps of it in a coil. The Explorer will not pick it up at all. So there are some metal objects that no metal detector will pick up, GARY

 

[Anonymous]

Hello Mike. I want to venture a general answer and a technical answer.
The gold chain and small gold nuggets will produce a weaker signal due to the fact they have a higher frequency where the peak R (Resistive effect) occurs. So for small gold a higher frequency is best. 100 kHz would be excellant for standard sine type detecors but rejecting the ground would be more difficult.
The explorer is essentially a pulse detector (producing a square wave or series of square waves) and the front end/ filters are set up to anaylze a range from 1.5k to 100k. So small gold is falling at the upper end of this range and thus is not optimised for small gold (bigger gold excellant though).
Example: a silver dollar has a peak R of 800 Hz so it falls at bottom of range. If you stack a bunch of silver dollars the peak R goes even lower. This is why The explorer is poor on stacked silver dollars(They have to be in contact with each other).
I have tested the Explorer on a small nugget about the size half as big as an eraser on a pencil and I can detect it at 3" (standard 10" loop). I can also detect on top of very bad iron mineral ground. Several other detectors I've tried won't do this. This is in the discrimination mode sensitivity at 22 manual.

 

[Anonymous]

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[Anonymous]

Hi Frank,
Thanks for a very informative and enlightening answer. Which, also backs up what Gary said concerning him not being able to detect the roll of silver solder.
Now, concerning the front end filter/filters. If they are designed with cutoff frequencies of 1.5 khz (low end) and 100khz (high end) respectively, with the optimum performance being in the neighborhood of 50 khz, I would indeed gather that this would be more of a multi-purpose detector, if, as you say, a good frequency for small gold would be 100 khz. So, it would stand to reason that you would not get much of a signal on small gold. However, it had been my understanding that the Minelab detectors in general were pretty "hot" on gold. But, it may be that that was pertaining to larger gold items.
It would appear to me (concerning filters) that one detector could be built utilizing a switchable filtering system consisting of two or three filters, each being peaked in a particular frequency range for the precious metals being sought,exlatinum, silver, gold. Thereby providing the hunter with one tool with which he could switch to the "hot" mode for the particular metal being sought.
Just a thought. Hey, there may even be a detector like that out here somewhere. Like I said, I'm new to the hobby and just learning. But, with the little I do know about surface mount technology and miniaturization, it certainly seems conceivable to me that you could truly have an all purpose detector that could be "hot" on several things, without having to invest in specialized machines for just one target.
Your thoughts/comments/or further information please.
Mike

 

[Anonymous]

Hello Mike. Yes I would say the Explorer is a general purpose detector. And it excels in detecting larger gold (rings, larger nuggets).
I thought of your idea of having the ability to shift the optimum fiter response up or down. Up and getting smaller gold would be much improved. prabably shifting down wouldn't be that useful but may help on silver quarters, halfs, and silver dollars.
The Minelab SD2200 and GP Extreme are designed to be opitimzed for small gold as well as large gold. Also the coil size and design effects how well it responds to small gold.
I was planning on trying the Explorer in old gold mine tailing piles where large gold nuggets can be found. Talk to you later.
Frank