TID numbers in mineralised ground

[brgordon17]

Hi all,

I have recently purchased my first MD. It's an xterra 705 Gold that comes with the 10x5 HF DD and I'm having a great time learning the machine and digging up plenty of ground. I've found about 30 coins in my backyard alone. I live in far north Queensland in Australia and have access to plenty of old gold mining areas and I've taken the XT out to these places twice now.

The area I hunt is very mineralised with constantly changing soil conditions and plenty of hot rocks (more like hot dirt clods) and plenty of old ferrous mining trash. I run the machine in prospecting mode, iron mask 5, sensitivity from 15-20, threshold around 8, I auto ground balance regularly (balances at 50-70), auto noise cancel (sets to 0).

I have found that the sensitivity begins to chatter at 28 and while I initially backed it off to 26, I found I had to run it lower as it chattered when swinging the coil. I have found that GB tracking worked well but where I hunt, the soil changes so quickly that the tracking GB struggled to keep up. So now I just use auto GB once I start hearing the GB going out. I'm yet to give the GB offset a go but will do this on my next trip out.

I have also learnt that hot rocks tend to have a more "quieter/rolled/smoother" signal, whereas metal targets are more pronounced and "sharper".

Anyway, I have a question that I hope some of you more experienced users can help me out with:

1. My main question is with the TID numbers. Initially, I would use prospecting mode and when I hit a target I would switch to coin mode to get an ID; If it was in the negatives I would generally ignore it as iron trash. However, I decided to dig a few of these iron signals and found a few .22 lead bullet projectiles (which means the place probably hasn't been detected before). They were definitely ringin up negative numbers with the wrap-around to 48 on the TID. Now I always assumed that lead and gold would show up very similar so I was little confused. Has anyone else noticed that lead shows as iron on the TID in hot ground? What about gold in hot ground? Woould I expect a similar response.

My next outing will involve experimenting with the GB offset and digging everything.

 

[Old Longhair]

IMO.....
First, you would probably do better if you left GB Tracking on, as it can compensate fast and continuously. If it's struggling to keep up, you're swinging too fast for the machine too operate accurately.
Second, your odd negative numbers are likely indicative of GB being "off" over that particular patch of ground. That said, you can alter those numbers some by playing with the GB Tracking Offset on your next outing. However, neither lead or gold should be anywhere near -8, so wrapping around to 48 isn't probable, and multiple targets are more likely. Your wrap around high tones and inaccurate numbers may also have been the result of a little too fast swing speed. Often in sparse trash when I experience odd high tones, swinging too fast for conditions is the culprit.

Slowing down is the hardest thing to do, but it's the most beneficial thing anyone can do with a capable machine. In hot ground you have to go slow because the potential target density is so high (mineral "clumps"), and in mild ground it's quite the same because you're looking deeper, so again the potential target density may be greater than one would necessarily think (be it iron, minerals, or other trash).

 

[brgordon17]

Thanks for your help OL. This is just the sort of feedback I was looking for.

My swing speed is probably 1-2 seconds for a 1 metre sweep (just over 3 feet) and after reading some other posts I see it should be more like 4-5 seconds. I am heading out again this weekend and will swing slower, tracking on and give the offset a try.

Cheers,

Ben

 

[Old Longhair]

Good luck Ben. Let us know how you get along.
HH!