High frequency search coils for Nexus Standard MP

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High frequency search coils for Nexus Standard MP

Post by Nexus » Fri Mar 17, 2017 11:11 am

After numerous questions and requests regarding high frequency search coils for Nexus Standard MP I have decided to grant our customer's wishes and a couple of months ago have initiated a development of the mentioned above coils.
Soon there will be few high frequency coils available for Nexus Standard MP;

13"DD @ 14kHz - the initial prototypes are detecting hammered penny Edward III at 14" in ground.
10"DD @ 18kHz - the initial prototypes are detecting hammered penny Edward III at 12"+in ground.
9" concentric @ 24kHz - the initial prototypes are detecting hammered penny Edward III at 10" in ground.
The mentioned above depths are considered to be with good signal response. With faint and very faint responses some extra depth can be achieved by those who have the patience to work in such manner.

The tests were carried out in soil conditions very similar to most UK detecting sites. All tests were done in all metal mode. With slower sweep speed the same depths are possible in Iron Rejection mode as well.

In heavier soil conditions all depth results will be lower depending on the site.

The 9" concentric coil is specifically designed for use in highly contaminated areas. When fitted with the 9" concentric coil the MP exceeds completely the target separation capabilities of any detector including the Deus.

The mentioned above DD coils are of the same design as the current DD coil range.
The 9" concentric coil is going to be manufactured from specially molded Fibre Glass shells.

Some detailed reviews will follow for each new search coil.

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Re: High frequency search coils for Nexus Standard MP

Post by Mega B » Fri Mar 17, 2017 12:05 pm

Fantastic news,the Concentric coil will certainly be on the shopping list as will be the 10'' 18khz coil,will await further updates as and when they will be launched ::g
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Re: High frequency search coils for Nexus Standard MP

Post by Filternozzle » Fri Mar 17, 2017 10:21 pm

I'm really looking forward to the 13" 14kHz and the 9" concentric 24kHz coils and believe the addition of these coils will give the MP more flexibility. ::g The sooner they are available the better as far as I am concerned.
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Re: High frequency search coils for Nexus Standard MP

Post by Nexus » Tue Apr 04, 2017 6:11 pm

Some pictures from the finalized design of the 9" concentric 24kHz search coils.
The available colors will be black resin and silver carbon.
These search coils will be known as the "Silver scout" series in which there will be an 11.5" version added soon.
The retail price for the 9" coils will be 250 Euros and they will be available in 3 weeks from now.

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Re: High frequency search coils for Nexus Standard MP

Post by Mega B » Tue Apr 04, 2017 6:56 pm

Will certainly be ordering one of the black ones ::g
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Re: High frequency search coils for Nexus Standard MP

Post by Filternozzle » Sat May 13, 2017 7:59 pm

Georgi, how does the new 11.5" concentric 24kHz compare to the smaller 9" coil on an Edward silver penny in the ground?
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Re: High frequency search coils for Nexus Standard MP

Post by Nexus » Sat May 13, 2017 9:35 pm

Filternozzle wrote:
Sat May 13, 2017 7:59 pm
Georgi, how does the new 11.5" concentric 24kHz compare to the smaller 9" coil on an Edward silver penny in the ground?
I would say with a good strong signal the 9", 24kHz coil will get Edward III silver penny at 8" in average ground, the 11.5", 24kHz coil will do 10" on the same coin in the same ground.
In ideal conditions the 11.5" coil will get the hammered penny at 12" maximum in the ground and this result will require some skill to be achieved.
The very good quality that these 24kHz coils exhibit is that they can get at exactly the same depth in the ground both hammered silver and hammered gold coins. Hammered gold coins are known to be notoriously difficult to get at any depth, which makes them more rare to find than they could be in reality.

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Re: High frequency search coils for Nexus Standard MP

Post by Ten pence! » Sat May 13, 2017 11:35 pm

An Edward III penny at 14 inches in the ground? :-/

This is about twice the depth you'd get on most current machines.

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Re: High frequency search coils for Nexus Standard MP

Post by Nexus » Sun May 14, 2017 7:34 am

Ten pence! wrote:
Sat May 13, 2017 11:35 pm
An Edward III penny at 14 inches in the ground? :-/

This is about twice the depth you'd get on most current machines.
Edward III penny at 14 inches in the ground is the maximum that can be expected from the 13"DD coil @ 14kHz and only in ideal conditions, like light dry soil with no iron near the coin location. Achieving this kind of depth will also require some skills with the detector.
This is why on the Hammered coins video test Edward III penny is buried at 12 inches in the ground, not the maximum possible detection depth. At 12" the signal is quite obvious and can be repeated by many users.
https://www.youtube.com/watch?v=A45JjBZcikk&t=2200s

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Re: High frequency search coils for Nexus Standard MP

Post by Ten pence! » Sun May 14, 2017 10:59 am

I'm sorry to say I think your claims are a bit misleading, theoretical depths are meaningless out in the field. In my experience, and due to the physics involved with VLF technology, all top end machines have more or less the same depth give or take an inch, other factors then come into play such as for example recovery speed, target separation, stability etc.

How do I know this? By having a long established test garden and testing every machine I can beg steal or borrow.

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Re: High frequency search coils for Nexus Standard MP

Post by Filternozzle » Sun May 14, 2017 12:17 pm

Ten pence! wrote:
Sun May 14, 2017 10:59 am
I'm sorry to say I think your claims are a bit misleading, theoretical depths are meaningless out in the field. In my experience, and due to the physics involved with VLF technology, all top end machines have more or less the same depth give or take an inch, other factors then come into play such as for example recovery speed, target separation, stability etc.

How do I know this? By having a long established test garden and testing every machine I can beg steal or borrow.

You have tested the updated Nexus MP with the 13" DD coils then? If not maybe you should. Did you look at the link provided? There wasnt anything theoretical about it. Your opinion which you are entitled to is based on your experience, which doesn't include use of the detector and coil in the thread..... sorry but in my opinon, your opinion has little validity in this instance Ten pence.
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Re: High frequency search coils for Nexus Standard MP

Post by Ten pence! » Sun May 14, 2017 2:20 pm

As someone once said, "Ye cannae change the laws of physics!" :))

Sorry to put a downer on things but there are very well understood technical reasons why VLF machines are limited in depth, if this was not the case we'd be seeing large increses in depth from all the main manufacturers, the fact is detecting depth has not really incresesed in twenty years, in fact the best machines for pure depth on my test bed have been the ancient second edition of the Minelab Explorer and the Fisher CZ6! Throw some iron into the mix or swing a bit to fast and it's a very different story. We don't detect in the field by hovvering the coil over a known target!

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Re: High frequency search coils for Nexus Standard MP

Post by Nexus » Sun May 14, 2017 2:43 pm

Ten pence! wrote:
Sun May 14, 2017 2:20 pm
As someone once said, "Ye cannae change the laws of physics!" :))

Sorry to put a downer on things but there are very well understood technical reasons why VLF machines are limited in depth, if this was not the case we'd be seeing large increses in depth from all the main manufacturers, the fact is detecting depth has not really incresesed in twenty years, in fact the best machines for pure depth on my test bed have been the ancient second edition of the Minelab Explorer and the Fisher CZ6! Throw some iron into the mix or swing a bit to fast and it's a very different story. We don't detect in the field by hovvering the coil over a known target!
The laws of physics do not define in any way the limit of VLF detectors depth.
If you believe I am wrong please quote the relevant scientific article.

Detecting depth was increased by average factor of 40% back in 2004 by the first Nexus resonant tuned detectors. Now the Nexus MP can do marginally better depth wise with addition of some other qualities.
Ten pence! wrote:
Sun May 14, 2017 2:20 pm
"How do I know this? By having a long established test garden and testing every machine I can beg steal or borrow."
"We don't detect in the field by hovvering the coil over a known target!"
These two statements do not seem fit one another.

The technical reasons for the depth limits on most VLF detectors are quite different from what you believe.

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Re: High frequency search coils for Nexus Standard MP

Post by Ten pence! » Sun May 14, 2017 8:08 pm

Don't take my word for it, check out the Fisher website, specifically the jottings of Dave Johnstone the designer of several Tesoro, Whites and latterly Fisher and Teknetics machines.

In a nutshell the ground is conductive as is of course the target, as the target gets deeper the conductivity of the ground gets stronger and the targets conductivity gets weaker, at some point the ground signa overwelms the target signal, VLF's according to Johnstone hit a brick wall and no amount of fine tuning or tweaking can overcome the fact the ground is more conductive than the target.

In my test bed I have a smooth but unclipped Lizzie halfgroat buried at five inches, only a handfull of machines I've tested over the years will give what you would call a digable signal. Again most top end machines in my experience perform pretty much the same depth wise, needless to say I tend to be more interested in things other than outright depth as this has it's physical limits.

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Re: High frequency search coils for Nexus Standard MP

Post by Filternozzle » Sun May 14, 2017 9:13 pm

Ten pence! wrote:
Sun May 14, 2017 8:08 pm
Don't take my word for it, check out the Fisher website, specifically the jottings of Dave Johnstone the designer of several Tesoro, Whites and latterly Fisherdetectinga coin size object at 6".etics machines.

In a nutshell the ground is conductive as is of course the target, as the target gets deeper the conductivity of the ground gets stronger and the targets conductivity gets weaker, at some point the ground signa overwelms the target signal, VLF's according to Johnstone hit a brick wall and no amount of fine tuning or tweaking can overcome the fact the ground is more conductive than the target.

In my test bed I have a smooth but unclipped Lizzie halfgroat buried at five inches, only a handfull of machines I've tested over the years will give what you would call a digable signal. Again most top end machines in my experience perform pretty much the same depth wise, needless to say I tend to be more interested in things other than outright depth as this has it's physical limits.
Hi Ten pence!
would appreciate a link to the specific information you are referring to by Dave Johnson - I cant find anything supporting your comments, although I do see in in question 11 that they refer to their 4" coil being capable of detecting a coin size object at 6".
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Re: High frequency search coils for Nexus Standard MP

Post by Ten pence! » Sun May 14, 2017 9:27 pm

You were on the right site and you seem to have missed it, it's question number six, specifically "Are we maxed out as how deep VLF's will go?

The answer is yes and the reasons are given as to why, again it's about the conductivity of the soil, Johnstone also goes on to explain there are several ways to partially mitigate this but at the end of the day it's simply not possible with VLF to get the large depth increases we'd all like to see.

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Re: High frequency search coils for Nexus Standard MP

Post by Nexus » Sun May 14, 2017 9:44 pm

Ten pence! wrote:
Sun May 14, 2017 8:08 pm
Don't take my word for it, check out the Fisher website, specifically the jottings of Dave Johnstone the designer of several Tesoro, Whites and latterly Fisher and Teknetics machines.

In a nutshell the ground is conductive as is of course the target, as the target gets deeper the conductivity of the ground gets stronger and the targets conductivity gets weaker, at some point the ground signa overwelms the target signal, VLF's according to Johnstone hit a brick wall and no amount of fine tuning or tweaking can overcome the fact the ground is more conductive than the target.

In my test bed I have a smooth but unclipped Lizzie halfgroat buried at five inches, only a handfull of machines I've tested over the years will give what you would call a digable signal. Again most top end machines in my experience perform pretty much the same depth wise, needless to say I tend to be more interested in things other than outright depth as this has it's physical limits.
The right thing to do is to observe personally how Nexus works first and talk later and let see if you would have much to say then.
Would you please let us know what are the other things that you are more interested in than the outright depth, so we can take a note on what we are missing in here?

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Re: High frequency search coils for Nexus Standard MP

Post by Ten pence! » Sun May 14, 2017 10:04 pm

Can you explain to us how you've managed to get all this extra depth? Specifically the technical side of things, I like that sort of stuff!

As you already know boosting the signal strength doesn't really work as the target still remains invisible at depth, processing the signal also has it's limitations as Johnstone carefully explains in his Q&A.

Sorry to be so skeptical but I've heard most of the claims before and always found them wanting, especially when I've managed to get my hands on the latest wonder machine or accessory, performance increases seem to be marginal at best in my experience .Given the limits of VLF technology I tend to go for machines that have fast recovery speed in mineralised ground and work well if there is iron around, some surprisingly cheap machines will outdo some very expensive ones in this respect, I won't name names as we are not allowed to compare machines on here! :))

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Re: High frequency search coils for Nexus Standard MP

Post by Nexus » Sun May 14, 2017 10:39 pm

Ten pence! wrote:
Sun May 14, 2017 10:04 pm
Can you explain to us how you've managed to get all this extra depth? Specifically the technical side of things, I like that sort of stuff!

As you already know boosting the signal strength doesn't really work as the target still remains invisible at depth, processing the signal also has it's limitations as Johnstone carefully explains in his Q&A.

Sorry to be so skeptical but I've heard most of the claims before and always found them wanting, especially when I've managed to get my hands on the latest wonder machine or accessory, performance increases seem to be marginal at best in my experience .Given the limits of VLF technology I tend to go for machines that have fast recovery speed in mineralised ground and work well if there is iron around, some surprisingly cheap machines will outdo some very expensive ones in this respect, I won't name names as we are not allowed to compare machines on here! :))
The best way to achieve more depth is by better ground control. Your detector will be only as deep as it can master the ground interference. How it is done in the Nexus MP it is a trade secret. You will have to excuse me if I am reluctant to share it.

Boosting the signal strength actually works very well. Nexus MP for example transmits in average 15-20 times more intense field than most other VLF's. All Nexus detectors are relatively high power output detectors.

As for work next to Iron please take a look at the video links below. You will see that the MP been one of the slowest in recovery speed is capable of little miracles amongst Iron.

https://www.youtube.com/watch?v=sK-xYoxQZLY&t=4s
https://www.youtube.com/watch?v=yKXwQ0pyjz4&t=302s

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Re: High frequency search coils for Nexus Standard MP

Post by Filternozzle » Sat May 20, 2017 8:28 am

Nexus wrote:
Tue Apr 04, 2017 6:11 pm
Some pictures from the finalized design of the 9" concentric 24kHz search coils.
The available colors will be black resin and silver carbon.
These search coils will be known as the "Silver scout" series in which there will be an 11.5" version added soon.
The retail price for the 9" coils will be 250 Euros and they will be available in 3 weeks from now.

Image
Image
Image
My order is in for the 11.5" Silver Scout coil, I have a couple of sites where it should prove to be very useful. My feeling is this will give additional flexibility to my MP which is most welcome. It weighs in at only 365 grams (less than 13 ounces).
Updated NEXUS MP & Minelab GPX-5000 ::g

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