making/modifying imaging coils

[Justin E]

I'm thinking of getting a Garrett GTI 2500 but want to increase depth. I'm wondering if there is some way to modify the detect or coil to pick up deeper and smaller signals better. Also, would it be possible to make a DD imaging coil? Thanks for the help!

[Carl-NC]

Also, would it be possible to make a DD imaging coil? Thanks for the help!

The "imaging" aspect relies on the response from 2 different sized RX coils, so you probably couldn't do that with a DD.

[Justin E]

Ok. Not sure what that is yet. Would it be possible to get more depth by modifying the stock coils or would that require altering chips and programs?

[Skippy]

I'd wondered how well an 'imaging' type DD coil would work myself. It would appear easier to make than a dual-Rx concentric (not that any coil is easy), as each Rx coil can be independantly nulled. Are you volunteering to be the first to try and build one? It may prove difficult to match to the detector.
I was going to ask what do you think is limiting the depth of your detector, the ultimate all-metal depth or the 'good-discrimination' depth? If it's the ground that's the main problem, then you won't gain too much from the bigger coil. But.... I see you haven't got the detector yet.
Better to tinker with the electronics first, eg. increase the front-end gain, try lower-noise amplifiers etc. You could probably get 5 to 10% extra depth that way.

[Justin E]

Yeah, I'm trying to do research first. I like the 2500 but wouldn't mind less weight and more depth/sensitivity. I've got ideas for the weight and armrest. I just need someone more knowledgeable of the technology part. I'd be willing to try if I had someone with more knowledge and tools. Might be able to do something pretty cool with this.

[ivconic]

Ok. Not sure what that is yet. Would it be possible to get more depth by modifying the stock coils or would that require altering chips and programs?

I don't know what do you asking more from GTI2500?
GTI2500 is hell of a deep detector, trust me.
But there is one major drawback at it; which may cause lot of confusion and impression that it actually is not so deep.
Discrimination at GTI2500 is to stiff, to strong, have impression that it was designed that way only to satisfy USA soils conditions but not others too.
I had 2 GTI's so far and also noticed that it actually don't see some smaller items at all, if working in some of Disc modes?
Usually i worked at Zero, but even than it can easily miss smaller coins?!
But in All Metal mode it is real beast, extreme deep.
I don't believe that there is a space for gaining more depth with it, than is already done by manufacturer.
What Garrett could do - is to adapt GTI 2500 for European soils (and other nonamerican) better and offer additional presets and adjustments, so that operator can manually fine readjust Discrimination level in smaller steps.
I don't see the point why Garrett left GTI2500 as it is and turned to produce such crapy models like Ace series?
GTI2500 is full with potentials and could be further redesigned and improved.
They just need to modify it and add better control over Disc functions.
So... i can't tell for sure; but i think that you misjudged GTI 2500 and mixed/confused it's real depths with fact that actually Disc circuitry is the one to blame, too stiff it is.
If i have wrong impression - i am sorry!
Regards!

[Justin E]

So, the problem is the discrimination? Hmm... No way to fix that other than all metal mode then. Still brings on the sensitivity to smaller objects, such as smaller coins. I've heard complaints on that, weight and the armrest.

[ivconic]

So, the problem is the discrimination? Hmm... No way to fix that other than all metal mode then. Still brings on the sensitivity to smaller objects, such as smaller coins. I've heard complaints on that, weight and the armrest.

Yes, GTI is heavyweight one!
Especially if you have larger coil with it.
I had Scorcher non imaging (30cm as i recall) with first one and 12.5 inch Imaging coil (black "spider") with second one - both arm breaking!
But in time you get used on it, not a big deal.
Mentioned 12.5 inch Imaging coil is Garrett's best ever!

[Justin E]

There has to be some way to knock off a little weight. Too bad there's no way to cut down on the number of batteries or use some type of lighter battery pack. Maybe carbon fiber rods ir something?

[ivconic]

There has to be some way to knock off a little weight. Too bad there's no way to cut down on the number of batteries or use some type of lighter battery pack. Maybe carbon fiber rods ir something?

Actually; Garrett GTI 2500 is extra high quality made, most probably the highest quality material i ever seen at metal detectors.
Despite it is "digital" with huge LCD and soft knobs - it is so resistant and reliable and long lasting! Bravo to Garrett for that!
Anything you can do at it and change original setup; may take you to risk to bust something!
Common failure i've seen at GTI2500 are those small "notches" which are preventing battery pack to slide out. Only failure that i ever seen at GTI so far.
So you better get use on it the way it is now and don't pick it to much!
Your arm will get stronger in time, in few weeks you will not pay much attention on it's weight.
(obviously you never tried to work with Minelab GP 3000! )

[Justin E]

Ok. What depths do you usually get?

[ivconic]

Ok. What depths do you usually get?

In All Metal mode usually it can punch out larger coins from 35-45cm depths! Extraordinary!
Larger items (10x10cm) up to 80cm depths.
At Zero Disc it is also deep, but only on nice and fat coins, but not so sensitive on bad coins.
On larger bad coin it can "ring a bell" only in one swing, but when returning swing back - it is silent? Same as on smaller coins.
That's because of the Disc circuitry.
Do a little test, bury few coins at various depths, starting from 15cm up to 40cm and check at them in all Disc modes and than in All Metal mode.
Larger, fat and nice coins will be detected with no efforts at all, in all modes.
But smaller "burned" bronze coins will produce no response at all in Disc modes, only in All Metal.

[Justin E]

Wow! Almost up to the T2 max depth! How does it do on smaller coins? I've heard it doesn't pick them up too well.

[ivconic]

Wow! Almost up to the T2 max depth! How does it do on smaller coins? I've heard it doesn't pick them up too well.

Like i said, it is close to deaf on small coins, in Disc modes.
But is more than good in All Metal mode.
T2 is funny toy comparing to GTI2500, trust me.

[Justin E]

So, back to the discrimination. Would a coil mod or something fix that or just the nature of the beast?