Tone but No ID Displayed /w GTI 2500

[Vancouver Steve]

As suggested in the forum, I have spent a fair bit of time running only in the various discrimination modes since getting my 2500 last year. Today I thought I would try playing with the big boys and run in the All Medal mode while MDing at one of the local football fields. On a couple of occasions while in the All Metal mode, I would get a solid and distinct tone, but no ID would indicate on the display. I tried sweeping over the target quickly, then slowly, and I even tried Bill's twitching technique in an effort to get an ID to show up - these were strong, repeatable signals.

To experiment, I switched to the Jewellery Mode and in each case, the Iron segment would indicate (no tone of course), and then when I switched back to All Metal mode, it would generally ID iron after that. I dug the target, and found nails etc., in keeping with the iron ID. This only happened a couple of times, and generally speaking in the All Metal mode, it would ID if there was a tone indicating a target, but sometimes it took a few passes of the coil. Anyone else experience this, and any theories on the cause?

I'm used to seeing coin sized targets mostly at 1" - 4" while running in the Jewellery and Coin modes, but in All Metal mode, I saw lots at 6" plus, and when I switched to a discrimination mode, they would disappear; What a difference! Recognizing soil types etc., is this a typical increase of depth for coin sized targets?

 

[fongu]

The all metal picks up deeper targets, but it also picks up targets from farther away. It picks up targets at the extreme edge of the coil and that may be why nothing is showing on your display. the object it is picking up is further away. rusted nails give off a signal like a coin or good target, I believe. The experts can answer this better than I can, what I am saying is based on the manual, what I've heard on this forum and what's happened to me out metal detecting. Good luck.

 

[fongu]

What kind of coil are you using? Some coils are non-imaging and will show up on the GTA scale, but not imaging scale or I.D.

 

[Vancouver Steve]

Fongu: You may be onto something! I was using my non-imaging Garrett 5X10" Scorcher DD to slip around all of the trash... During the hunt, the 2500 was normally providing an ID on most targets, but in those cases where it didn't, switching to a Discrimination Mode would provide an ID, that seemed to hold when I flipped back to All Metal. In all cases when it didn't ID without switching modes, it was low on the scale - iron.

 

[Uncle Willy]

Yeah not all the coils are imaging coils.

Bill

 

[Vancouver Steve]

To clarify, when I say that it wouldn't ID a target, I referring to the numbering scale representing conductivity, not the imaging sizing scale.

Thanks to everyone so far for their comments.

 

[Vancouver Steve]

To continue the experiment, I was out today again running All Metal, with the 5X10DD coil. On deep targets that wouldn't ID in All Metal, and that were too deep to even signal in Discrimination Mode, I noted that it would ID when I went to Pin Point. I am still amazed and the difference in depth in All Metal vs. Discrimination.

For what it's worth...

 

[Alan Applegate]

It has been my experience, that this happens both in all metal, and discriminate modes. When it does, it is always an iron object of some kind, and usually very rusty. A short piece of bailing wire is often the culprit in these parts. And, after digging all manner of junk, I've come to the conclusion that if it doesn't show on the GTI, it's junk!