How Deep Do Today's Detectors Go Compared To Older Technology?

[Jonathan Porter]

There's a key issue to think about when using larger coils which is mainly why you don't see Minelab going much above 19" and I notice no one has mentioned it here in all the dialogue. 

SALT

JP

[Jin]

In one of your videos JP,  Bruce Candy said that when you get up over 20" that the magnet field in the ground starts to play havoc (or something like that)

[auminesweeper]

9 minutes ago, Jonathan Porter said:

There's a key issue to think about when using larger coils which is mainly why you don't see Minelab going much above 19" and I notice no one has mentioned it here in all the dialogue. 

SALT

JP

Most VLF's see very little effects in using coils bigger than 15", At one time large coils could be used but at the cost of sensitivity to small items, Alas now this is not the case, My 15" Concentric is as sensitive as my 6x10 (5x9) and the only coil I have for my  VLF that is hotter than the rest is my 5.3 (6") Concentric and it can go down to 0.006 grams with surface targets, where all my other coils only go down to 0.03 to 0.02 grams.

[Norvic]

2 hours ago, auminesweeper said:

I bought a few of their coils back about 12 years ago and was not overly impressed with them but this last 5 or 10 years their coils are about as good as it get, Right when I had all but given up on  my quest for more depth I was doing the Ebay Tango and saw the one coil I was told not to buy back in the day so last year I bought it, Not only is it a delight to swing but it has added 2 or 3 inches on coins and close to 12"+ on larger items, So I ordered a second one just in case, It can see bits weighing 0.03gm within an inch or so and it has the power ta boot.

I have come to a point where I now believe that the extra horsepower now lies within coil technology because my detech has really opened up my machine and the other 8+ coils have become more like accessories and I am more than happy with depth on a daily bases, to the point where although my machine is getting on in years by design although it is only 2 years old I just don't want another machine and I think that this is bought on by my choice of coil/s.

I truly believe that the future lies in coil selection and design because my VLF now whoops my SL by a fair margin.

John.

The Dtek, (actually spelt D-Tex) I speak of, were only trading in the early MD years to my knowledge. Their main products were the Search King, the Gold King and there also was a Money King I believe. I have found some info on them as per below but there is probably more on the net.

https://www.treasurelinx.com/d-tex.html

 

[PhaseTech]

On 12/3/2017 at 4:17 AM, Steve Herschbach said:

“Sharp is similar to Normal but creates a more powerful detection field. It is capable of an improvement in depth, but is more susceptible to interference and will increase the severity of false signals in difficult grounds. This timing is best used in quiet conditions and can work well in combination with Deep Search Mode with a reduced Rx Gain setting. Sharp is an excellent tool for pinpointing faint signals due to the very "sharp" signal response. Sharp will work best with DD coils in most gold field locations.”

 

Have a guess who wrote that? 

[PhaseTech]

On 12/2/2017 at 3:37 PM, goldenoldie said:

Actually just found this video test between a GPZ and GPX on an undug target using larger coils.

 Hopefully Nenad does not mind me posting his test here on this forum and subject.

There appears to be very little difference between both the GPX and GPZ on this target.

Share away no probs. 

The big difference is that the GPZ in Normal with a slightly lower sensitivity could easily be run in that ground. The GPX would need the Sensitivity dropped to minimum, and you'd need to have good tolerance to noise. If I had a time machine, I would love to go back and try a big DD on the GPX. 

[Jonathan Porter]

23 hours ago, Jin said:

In one of your videos JP,  Bruce Candy said that when you get up over 20" that the magnet field in the ground starts to play havoc (or something like that)

He was referring to the salt signal, once a coil size reaches the tipping point salt dominates the signal negating the depth advantage.

JP

[Jin]

Gold Depth is always relative to Ground Noise - Minelab Treasure Talk- by JP

https://www.minelab.com/anz/go-minelabbing/treasure-talk/gold-depth-is-always-relative-to-ground-noise

[auminesweeper]

Yep but mainly it relates to PI machines, In short ground noise = Mineralization or mineralized hot spots, with VLF's it presents much larger issues, With new machines we have fast auto-track etc which deals with the changes but not with the feedback from the ground, It can be dealt with in a number of ways IE Whites V-SAT systems or/and running at a much lower gain but with the Older machines they were far better at dealing with such conditions, Where you could ground balance to help cancel out the ground like you can with newer machines but on the older models you could also adjust the DISC to cancel out any ground noise completely, and also they had a lot more power to the point of what a modern day machine can achieve using a 15" Concentric Coil the older machines can/could do using a 9.5" Coil.

When I spoke to a Whites engineer earlier this year he told me that a lot of power was lost when Detectors switched from Analogue to Digital, Because It was the Analogue components that created the Power, where as now it is all done via digital software,

Until a person can run side by side tests as I have done comparing the two technologies only then will you see the differences between them, and to be honest it is a Bitter pill to swallow.

John.