Do I have a faulty coil, or is there a flaw in the X-Terra's design?

[Mick in Dubbo]

I've been taking a club member out all through the last week, to show him how to hunt with a coin machine. We've been having a great time and uncovered the largest mens ring I've seen as well as having some good success in some very trashy ground. I think he is sold on the 30, as he can't believe how good you can discriminate with it. He is used to gold hunting.
My question is, that I often get a target that is 3 inches outside of the outer edge of the coil to tell me, that it is in the centre of the coil. It did this on our last hunt, and I often had times, where the detector is telling me that a target is there, when it is not. Is this normal behavior for the X-Terra? I have sent it back to Minelab before, and they have given both the coil and the control box the all clear. Actually, on it's first return, that's what they said about all the faults that was in the machine at the time, with none of them being corrected. The second return sorted out the battery housing problem but not the pinpoint problem or the speaker problem, and on the 3rd send back, I asked that they replace the control box, of which they were happy to do. I did not send back the coil on this occasion as the warranty had run out on it. Perhaps I should have.
I would be grateful for any insights as to what is going on, as this is holding me back a bit from taking it out and enjoying it more often.
Thanks.
Mick Evans.

 

[claddagh]

Hi Mick,
I only have that if the target turns out out to be large round aluminium tin tops, or large iron (horseshoes) etc , but if the target is say a coin or similar size the pinpointing is excellent.
How does it pinpoint if you test various targets on top of the ground?.

HH, John

XT 70

 

[Mick in Dubbo]

G'day John.
It doesn't seem to matter what size the target is; on this occasion, it was a pull tab. It does it with coins as well. It seems to apply to shallow targets. As I use a screw driver for my recoveries, I mostly only go for targets that indicate 3 arrows or less (unless I'm not hunting on lawn). As surface targets are a bit close, I'll either raise the coil, pinpoint off the 12 o'clock position of the inner coil, X the target without the pinpoint mode, or use an electronic pinpointer. I have a strong preference to use the 12 o'clock method, but find that it is often compromised by the detector picking up metal away from the coil. This doesn't happen with my other detectors, so I'm keen to get to the bottom of it and enjoy getting back into using the X-Terra more than I currently do.

 

[claddagh]

G'Day Mick,
no doubt some of the more experienced guys will chip in here, but I guess if you could borrow another coil you could find out if its the coil or the control box, otherwise I dunno mate.
HH,
John

 

[Bavaria Mike]

especially with foil and tin type targets. This may sound weird but, seems like the target is at a slant in the ground and redirects the dang signal a bit maybe? HH, Mike

 

[JBM]

I use a Uniprobe (pocket version)and that finishes what the X-Terra 70 started.

Many of our finds come for depth and when I remove the top soil I dig out some more.

Thats when the quality Uniprobe comes in as sometimes the find is in the wall of the hole.Jerry.

 

[BarnacleBill]

On many detectors a coin laying at an angle presents a phantom or mirror image of sorts. The red circle in the diagram is where one ends up pinpointing, but the coin signal is also available at the green position. Next time it happens check to see if there is what appears to be another coin within a coil diameter that has a similar ID.

If this is a steel clad coin then really funky things can happen, even with the coin in a flat horizontal position, because sometimes the X-Terras will read iron with the coil in certain positions and silver in others. I believe this to vary by coil type/size and obviously the angle of the coin.

On an X30 since you can't see the coin ID in pinpoint, you may also be pinpointing to a deep piece of iron which you have disced out near the coin. I would also suggest X-ing the target in motion mode and comparing it to pinpoint to see if pinpoint agrees with normal mode. Also raising the coil in pinpoint mode may give some clues by signal drop-off characteristic compared to properly positioned targets.


[attachment 87770 phantom.gif]

HH
BarnacleBill

 

[Mick in Dubbo]

Thanks all.
There are some very interesting thoughts there. I can readily repeat this situation at home by placing a target to the side of the coil and have it picked up as being in the centre. It looks like raising the coil and or carrying the pocket probe out with me on each hunt, may be the best solution. ((I generally prefer to take as little as possible out with me when I hunt.) I'll hook up the DD coil to it this afternoon and see what happens.
I've organised a hunt with 3 of us going out today and the chap I've been showing the ropes to has borrowed the X-Terra for a month. He's pretty stoked with it.(But he can't keep it.)
Mick Evans.

 

[B.T]

I have never experienced a prob with my 70 pinpointing anything ever. Had mine since the first week they were released and it zero's in on targets like they were pre lazered by the military. Precise everytime regardless of coil used. If its a new box and same prob its gotta be the coil you'd reckon. Your having a bad trot Mick, might need to jump up and down a bit harder mate

 

[khouse]

I had the same problem with my old 30. This was the only problem I had with it so I sold it. Forward 2 years. I bought a 50 and the pinpoint was dead on. Then I traded the 50 for a new 70. Guess what? The pinpoint is dead on too. I can't explain it but that is my experience with the Xterra's.

 

[Mick in Dubbo]

I guess if millions of rain drops hitting the ground simultaneously will perk up targets for up to 48 hours, then if I can round up that mob of roos I've got loose in the top paddock; and get them to bound at 7.5 bounds per second, then I might be able to get those coins to jump right out of the ground!
On a more serious note. I think that it must be the coil. I've only ever handled one other X-Terra; and it was doing the same thing. So it had me wondering. I bought mine 3 weeks after they came out. It sounds like a new coil may be the answer. Hopefully this should turn a good detector, into a great one.
Mick Evans.

 

[Mick in Dubbo]

You had me wondering a bit there Kenny about the 30's. I remembered though, that I've seen a 70 do this as well. I think that it may be a good time to buy the small coil. I'll do that next month, when I get the 30 back again. It'll be nice to try the little coil and see how many targets have been missed because of masking. I'm looking forward to having an accurate pinpoint again.
Mick Evans.

 

[khouse]

I have the 6inch HF DD coil and it's real nice. You can PP dead center or off the tip. Either way is accurate. In most areas here I can run full sens or 2 clicks down. So it is a deep coil for sure. But the stock coil PP's real nice also. Both coils PP very well in the disc mode too.