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Re: I haven't tried the AT Gold w/4½" Concentric coil.

February 21, 2020 05:43PM
Well, theory proved correct. The AT Gold (5" CC) performs as well as the Impact (7" CC).What was the 'theory?' The use of a smaller-size coil or the use of a Concentric type coil? Maybe both?

The theory was (previous post) the requirement for passing the "Plank" test is 1) Fast recovery speed 2) Small concentric coil.

1) Without fast recovery speed, the detector swung E-W is masked by the nails since it cannot recover to pickup the nickel in between.

2) Without a small CC coil, when swung N-S, the 2 iron nails mask the nickel, since the blade like field pattern of a DD picks up more of the iron than the more pointed field shape of a CC.

The AT Gold has fast enough recovery, and with the 5" CC, it can capture the nickel target when swept N-S, not being overloaded with the iron signal.

I also changed the results of the Impact based on the depth at which the target can no longer be detected. I pushed the nickel down into the soil, until the detectors could no longer hit it. Both did about 1/4". Hey, that's progress smiling smileyTwo things were changed, and that is the Coin was slightly deeper than the Iron nails .... or .... the Nails were closer to the search coil than the Coin. Different point of view but with the same changes in the result, and that is analyzing what type of metal object has a greater influence on the more intense portion of the EMF. Not to mention the two have a differing effect on the Electro-Magnetic field to begin with sine one is ferrous and the other isn't.

I don't understand that, but the bottom line is instead of putting the nickel below a fixed 1x4 board, ~3/4" thickness, I simply pushed it down into the soil, until the detectors failed the N-S pass. That they can detect a good target 1/4" below 2 nails is encouraging.

Another important note: Neither the Gold nor Impact could hit a cu penny in the N-S direction, until I spread the nails to ~2" apart. The nickel just provides more non-ferrous volume.You lost me on that final comment, although it could be argued from the standpoint of the warped EMF. Well, maybe not argued but at least discussed.

Very simply, the penny has less total metal than a nickel. As long as the discrimination has high resolution, the penny is a tougher target to hit in amongst trash. The half dime would be even tougher. The plank test is failed by both the Impact and AT Gold with the 1-5/8" nail spacing. It takes a spacing of ~2" before a penny is detected.

But we need to consider why moving the Nails helped, and also consider the settings used and the search coils as well. One had a 4½" round Concentric and the other used a 7" round Concentric, so the 'type' of coil was unchanged, but their diameter, or size, could make a differences as well.
But if another Concentric coil could handle that w/o moving the Nails, what would that indicate?

Moving the nails got the the iron nails just enough out of the transmitted field shape that the detector could then "see" the good target.

Funny you mention "another concentric coil". I'm investigating the possibility of making a concentric coil that is 3" or 4" diameter (since the mfrs. will not) Maybe better is the coaxial coil which has an even more "pointed" sensitive area. There are trade offs, of course. The smaller you make the detected area to get in between targets, the less area you can cover per sweep of the coil!

Or if a Double-D coil could handle it with a 'lengthwise' sweep before changing the Nail position, what would that suggest?

That would suggest that you have SOME coil there! The sharper (smaller) (more pointed) your detection area, the better you will be able to get in between targets. If your detection area is large, the detector will see many targets at once and will have a harder time discriminating between them.

That brings me to another point. Since all modern detectors use digital technology now, the ones with the best "target separation" will have higher resolution analog to digital converters. Typical A/D converters are 8bit, 10bit, 12bit, 16bit, etc. resolution. The higher the resolution, the sharper the ferrous/non-ferrous break point.

I had considered an AT Gold at one time due to the operating frequency, but found that it fell short of what I was looking for.

Well, based on previous tests, I was looking for a machine that could best separate a good target with close surrounding iron trash. As stated above, the criteria was fast recovery time and small transmitted field area. The AT seemed to fit that. It passed the test! The other criteria that I'm acutely aware of is weight. The AT is light. The problem with the AT is balance. This can be addressed. I could hip mount it or build a shaft for it that balances.

Also, I've got 3 silver dollars coming so I can test the "silver stack".

Yes, I decided last night that this Iron Nail test will also use 1 US Nickel coin, and all I ask is for anyone to use their detector and coil of choice, size or type, set up as they would for Relic Hunting these old sites and sweep over the Test Set-Up. From any direction they choose, and if they can get one good audio response from the Nickel from the left and from the right ... from any position/direction they choose ... I will give them a $20 bill.

Monte, pass the test or not, I'd NEVER take your money. You have given us all so much. That would be stealing!
Subject Author Views Posted

Updated test results, AT Gold added Attachments

glabelle 307 February 19, 2020 11:49AM

Stacked silver dollar results

glabelle 118 February 26, 2020 09:01AM

Good information. Were the Silver Dollars all

Monte 122 February 26, 2020 05:33PM

Re: Good information. Were the Silver Dollars all

glabelle 110 February 26, 2020 06:02PM

I haven't tried the AT Gold w/4½" Concentric coil.

Monte 125 February 21, 2020 08:45AM

I updated my above post and withdrew the money offer. N/T

Monte 108 February 22, 2020 04:46AM

Re: I haven't tried the AT Gold w/4½" Concentric coil.

glabelle 104 February 21, 2020 05:43PM

George, I'll give some short replies.

Monte 111 February 22, 2020 04:37AM

Re: George, I'll give some short replies.

glabelle 111 February 22, 2020 08:08AM

Back to you, George.

Monte 111 February 22, 2020 09:33AM

Re: Back to you, George.

glabelle 106 February 22, 2020 10:12AM

George, 'Rippville' is huntable!!

Monte 107 February 22, 2020 07:45PM

Re: George, 'Rippville' is huntable!!

glabelle 101 February 22, 2020 07:50PM

Yes, we get to control our time .... sometimes ....

Monte 104 February 22, 2020 08:43PM

Re: Updated test results, AT Gold added

OregonGregg 118 February 19, 2020 04:07PM

Re: Updated test results, AT Gold added

diggindeep 113 February 19, 2020 04:04PM

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