I got out yesterday for another old coin hunt along an old dirt footpath which borders a river. There is a steep ridge on the other side of this path so the huntable area width wise varies from about 10 to 20 yards, even down to maybe 5 yards in certain spots where the ridge/river squeeze the path here and there.
The area is loaded with trash in spots, broken glass, old bricks, and so on. In fact, we found a few old cork bottles so that told me the area had plenty of activity going back to the 1800's. It was obvious after digging only pennies and the occasional clad that somebody had picked over this area pretty hard. It looked like they cherry picked the silver signals and any penny signals that were deep enough to be wheats or indians, because the penny signals we ran across were 3" deep or less. Still, with the power of the GT at both depth and unmasking ability combined with the added enhancements to those features that the 15x12 gives me, I'm always confident in working areas that others have hit hard. In fact, even if I was just using the GT with the 10" stock coil I'd have this confidence, but the SEF makes that feeling even stronger.
The area varied from deep black soil to clay, shale, and hot rocks in various spots. Still, I was able to run the GT at max sensitivity with no falsing, other than the occasional hit on iron, which was thick in some areas. This coil and the GT ran smooth as silk for the most part for me with no need to compromise on sensitivity.
About an hour or so into working this trail and the small wooded edges on either side of it between the ridge and the river I hit a deep 180 "coin" signal that sounded smooth and gave the proper ID from any direction. The audio was still loud but I could tell by it's level of loudness that this target was probably 9" or deeper based on my experience with prior dug targets at other sites.
Pinpoint could not hear the target at all. After more experience with pinpoint I'm convinced more than ever that it doesn't go anywhere near as deep as discrimination. PP seems to no longer be able to see a coin sized target once it get's passed about 8". For sure it doesn't go any deeper than 9", but I can pinpoint targets at about 7.5 to 7.75" deep, so I'm guessing it can't see targets deeper than somewhere in the 8" range or so. This makes for a good depth tool for those who have trouble determining depth by sound some times. If PP isn't picking it up you can figure the target is at least 8" deep or deeper. All this is based on this SEF 15x12 coil, of course, so you're results may vairy with other coils.
Anyway, since I had a feeling this was going to be a coin and was at least positive that it was not some kind of ghost signal or iron spike because it locked on solid and just sounded too good, I decided to play with my settings a bit to see how they reacted with this deep signal. I was pretty sure this was going to be the deepest target I've dug yet with my GT and any coil, or with any detector for that matter. Thus far the deepest coins I've ever dug on any machine were probably an indian and a v-nickle that were roughly 9 1/2" deep or so with the 10" coil on the GT. For all those reasons I wanted to play with this target and see what certain things did.
First thing I tried was flipping over to Silent Search and the GT had no problem still hitting hard and perfect on the target. It sounded just as good and exactly the same as it did in threshold mode, just without the constant background hum of the threshold. Next thing I did was to throw the GT into auto sensitivity and it could no longer hear the target let alone even null over it. Based on this and other tests I've done I'm guessing that automatic sensitivity maxes out at about 7 to 8" on the GT, maybe a little deeper if it isn't adjusting down too far due to RF noise or minerilzation/iron. Even at the spot the other day where I dug the standing liberty quarter it hit hard at like 7" or so, and that site had iron/minerals/and RF noise all working against it, so that was pretty impressive.
I then put the sensitivity back into manual and dropped it to 12 o'clock, or the halfway point. The GT could just hear the target and sound off but it wasn't hitting it hard or giving the proper ID. It mostly ranged in the 150's or so but never locked onto a specific number. That was very informative on what to expect from deep "coin" signals that are just out of range. I then moved it to halfway between that and max sensitivity, or in other words about the 9 o'clock position. The target was perfect again with loud audio and a 180 VDI. Even more impressive, because that's telling me that if the GT can hit this signal at that setting with no problem then I bet max sensitivity is pushing MUCH deeper than this target appeared to be.
Now I was anxious to see if this was a coin and more importantly how deep it was. After digging down probably 9+ inches I'm still not hearing the target with my ProPointer. Dug another inch or two down and now the propointer is picking it up, AND it looks like it's a coin sized target! Dug down another inch or so and still wasn't seeing it. Now I'm being real careful as I dig at the bottom of the hole because I know it's very close. I also wanted to see how this target was sitting in the ground.
Well, I wish I could say it was some old coin or other good find but as anti-climatic as this is going to be the target turned out to be a fishing sinker. But, I was still happy with the find only because of the good 5 to 8 minutes I spent playing with the GT to see where various things stand with it and the SEF coil. The sinker is only a little bigger around than a crayon and about one inch long. Not only that but it was standing straight up, presenting a very small image for the SEF coil to see. I know it was because I was careful thinking this could be a good coin and was slowly removing the dirt with my fingers. So, despite it not being a "keeper" it did show me a lot about the potential of the GT, this coil, and the various settings. As most of you know a lot of sinkers will give rather good/smooth coin signals. For that reason, it's depth, and the good ID/sound I got out of it I'm more convinced this coil is going to hammer some real deep coins even though I haven't dug any yet (but still haven't really hunted known deep coin sites with it yet either, not for any length of time anyway).
Oh, I forgot to tell you the depth...My digger is 11" long from tip to tail and that's how deep this sinker was! Yes, I've heard of the 10" coil and even the 8" Coinsearch hitting coins this deep and even at 12" or a bit deeper, but like I said I'm just happy this coild is at least getting that depth. Judging by how hard it hit and perfectly ID'd it, along with the same happening even at 3/4 sensitivity, I've got the added confidence that this coil and max sensitivity might be getting another 3 to 5" deeper on coins when conditions are right. This jives with what I've read about others using it, getting coins well into the "teens" as far as depth goes.
Oh, one more thing. I did dig a 1947 rosie. Not more than 3" deep, but laying in an area that had a lot of trash. Gave a good 181 signal both ways. Don't know how the prior guys who must have worked this site missed that. Well, I do know how...They weren't using an SEF! This spot was only about ten feet by 5 feet and right along the dirt path's edge so I know people would have worked it. Also, it had some large old oak trees nearby and a great view that would have drawn them to hunt it like a magnet. Not sure if it was on edge or not, but if anything I bet the trash kept it hidden from "lessor" coils and detectors.