Nexus Standard SE

[mschmahl]

I had the chance to get a used Nexus Standard SE with the double 9" and a double 6" coil. I like to try different technologies so i done the deal.
First tests of the nexus are very impressive. So it is my first "see through iron" VLF machine.
I have done a short video. The silver coin is a 1 oz .999 fine silver. The iron-pice is 7x2.5 cm.
http://http://youtu.be/Ya5uH3jYUeg

I´m new with the nexus and have not found a lot for handling and so on on the internet. So feel free to post experiences, tips and settings for this detector.
I have found some coins, buttons and musket balls on the first outdoor test with the 2x9"coil. And it is very sensitiv for small pieces too.
One musket ball was together with a nail in a lump of dirt.

[mschmahl]

Today i had a chance to go on an archeological excavation and search with the nexus in prospecting stripes. Such a strip is around 2-3 m wide and 50-70 cm deep unearthed.I also try the Lobo St with Mod (GB in Disc) and the explorer SE. Only the nexus could handle the changing ground conditions (herd provide, post holes, trash pits, from sandy to loamy,...) and give a noticeable signal. The other detectors gave for every groundchange a "dig me" signal. The nexus have it done similar but very weak. If there was an object than it came a very strong signal. Only the disc was lacking, but this is no problem. In this depht you dig all what give a "beep".

[Bill512]

"see through iron": old tricks from dealers. There is not any "see through iron" detector in our universe.
Also the statement:"Only the nexus could handle the changing ground conditions".
From what I have done in tests, I could say the exact opposite...

[crane]

"Only the nexus could handle the changing ground conditions"

There have been a few similar claims made here recently but the exact opposite occurred in a test conducted with a Nexus here in Australian gold field soil. It couldn't be ground balanced at all and this is what we would expect for a VLF with a resonant receive coil circuit. Some manufacturers use off-resonance for coin machines but you won't see a capacitor anywhere near the receive coil in any of the top VLFs used for detecting gold in highly mineralised ground and this is because the phase angle changes in sympathy with the coil's change in inductance and this can easily be 3 degrees with a high Q receive circuit, which is much more than the expected change in phase angle due to the varying soil signals. If the late models handle bad ground well then they must have stopped using resonant receive coils.

[Nexus]

"Only the nexus could handle the changing ground conditions"

There have been a few similar claims made here recently but the exact opposite occurred in a test conducted with a Nexus here in Australian gold field soil. It couldn't be ground balanced at all and this is what we would expect for a VLF with a resonant receive coil circuit. Some manufacturers use off-resonance for coin machines but you won't see a capacitor anywhere near the receive coil in any of the top VLFs used for detecting gold in highly mineralised ground and this is because the phase angle changes in sympathy with the coil's change in inductance and this can easily be 3 degrees with a high Q receive circuit, which is much more than the expected change in phase angle due to the varying soil signals. If the late models handle bad ground well then they must have stopped using resonant receive coils.

The statement is quite correct, but only for normal soil conditions.

Australian gold fields are highly magnetic and standard VLF including Nexus SE will not work there.
However our new Nexus Standard MP is also a resonant tuned VLF and it exceeds the performance of any other VLF in mineral fields, including the Minelab's FBS, BBS and other multifrequency technologies. The CTX3030 is by my opinion the most advanced VLF ever made, but that's in the digital domain.
The analogue electronics is still better, because it can achieve much higher resolution of adjustment, which is the very reason for the new MP to outperform the other digital based models.

I didn't bother filming other VLF detectors as the Minelab was simply the best of all. Later I tested the F75 and it turn out to be a very formidable opponent, showing marginally better performance on this field that the CTX3030. However the CTX can still work on very though black sand where the F75 can not, so the CTX is still a over all winner.

[Nexus]

"see through iron": old tricks from dealers. There is not any "see through iron" detector in our universe.
Also the statement:"Only the nexus could handle the changing ground conditions".
From what I have done in tests, I could say the exact opposite...

I am sorry, but there are no apparent tricks in the video.
Needles to mention there are no Nexus dealers in here. We do not sell SE for over a year now.
You'll probably claim that your tests were done with Nexus, but I am quite sure that's not the case.
You are welcome any time for some real demonstration to see with your own eyes that mschmahl is truthful in his statement.

[mschmahl]

For better understanding i have searched a picture in the internet, where you se such an archeological prospecting stripe. I used a different machines had set up each detector and then go in this strip. With the Explorer and the modded lobo i heard with every crossing from one ground to the other (light to dark brown and so on, see picture) a positiv signal (i name it phantomsignals). It was not only a slightly signal but a repeatable strong signal. I had dig such phantomsignals also. With minimal Sens on the explorer and lobo it was not so strong but still a "dig" signal. With the nexus it was possible to set the GB such, that you hear the phantomsignals also, but only similar to a slight treshold tone changing. In this setting objects gave a clear signal. So i could distinguish from groundsignals to objectsignals which i could not with the other detectors.

The "see trough iron" is not the correct term, it is a phrase. Therefor it starts and ends with ". The nexus is not so prone to masking effects how other detectors which i have used. It is more a "see close by" the iron. Don´t know if the deus could do this also, but i suspect it. Also the lobo with small coil can do it better than the explorer but not so good how the nexus with it´s doubble 9" coil (which is big).

I think my grammar is not so good, so forgive me.

[Bill512]

I am sorry, but there are no apparent tricks in the video.
Needles to mention there are no Nexus dealers in here. We do not sell SE for over a year now.
You'll probably claim that your tests were done with Nexus, but I am quite sure that's not the case.
You are welcome any time for some real demonstration to see with your own eyes that mschmahl is truthful in his statement.

sorry , but this was the case: "Nexus Standard MKII" with "SE Ultima" coil in red clay (terra rossa).

[Nexus]

sorry , but this was the case: "Nexus Standard MKII" with "SE Ultima" coil in red clay (terra rossa).
[ATTACH]31741[/ATTACH]

From this picture I can tell this SE Ultima coil was manufactured relatively recently. Since we sell very few of these coils how come we don't know about you?
If you had any problems with this detector was it not the right thing to do to contact us and discuss the GB issues? You seem to have good English, so why not call us, but come here to talk?
How many people you think in the entire world will be able to tell you what to do with this combination?

Let me be as clear as I can.
With Nexus the larger coils have much less GB problems than the small ones. This is because the larger coils in our designs are of the same Q as the small ones and use the same oscillator Voltage swing.
If you had problems with GB in this case it is entirely caused by lack of knowledge of how these big things operate. It is well explained in the User Manual, not that many bother to ever read it.

First step to getting things right is to turn the sensitivity control down. Do this and see what happens.

[crane]

... our new Nexus Standard MP is also a resonant tuned VLF and it exceeds the performance of any other VLF in mineral fields, including the Minelab's FBS, BBS and other multifrequency technologies. The CTX3030 is by my opinion the most advanced VLF ever made...

I only watched the beginning of the video but using a magnet to determine mineralisation can be very misleading because some highly magnetic minerals (that stick to a magnet) only produce an amplitude shift whereas other types, such as we have here, produce both large amplitude and large phase shifts. A "resonant tuned VLF" won't GB this ground. I would assume that similar ground can also be found in other parts of the world so I think the ground type would have to be known before you can blame operator error.

The CTX3030 transmits a continuous rectangular waveform and processes the signals in the time domain, it isn't vlf.

[mschmahl]

The CTX3030 transmits a continuous rectangular waveform and processes the signals in the time domain, it isn't vlf.

Hi crane!
I have a picturer for you from TX of Explorer SE.

If you look at this, what waveform did you see? According to your statement is the explorer no VLF also. But what than?

[crane]

Yes the Explorer transmits a continuous rectangular waveform.

As stated in at least one paper, the term "time domain" implies that the method employed is best analysed in terms of the temporal evolution of signals, just as "frequency domain" devices are best analysed in terms of the frequency and phase of signals.

FBS is an example of pulsed time domain, but some CW detectors using a pulsed tx waveform are best described using frequency domain art because they only measure the amplititude and phase of the receive signal, similar to vlf.

[Nexus]

I only watched the beginning of the video but using a magnet to determine mineralisation can be very misleading because some highly magnetic minerals (that stick to a magnet) only produce an amplitude shift whereas other types, such as we have here, produce both large amplitude and large phase shifts. A "resonant tuned VLF" won't GB this ground. I would assume that similar ground can also be found in other parts of the world so I think the ground type would have to be known before you can blame operator error.



The CTX3030 transmits a continuous rectangular waveform and processes the signals in the time domain, it isn't vlf.

If any ground/rock is magnetic (sticks to magnet) it will always and in every case produce an amplitude and phase shift together.

Why both?

Because the magnetic properties of the ground/rock sample will alter inevitably the properties of the windings of any search coil. Magnetic materials raise the inductance of all coils therefore phase and amplitude change occurs.

And yes. Nexus Standard MP is a resonant tuned detector and does GB any soil no matter how mineral it is including the severe black sand on the south coast of Bulgaria where only the CTX3030 works on the surface.

I have measured the CTX output and I am well aware what it transmits. The CTX is actually a wide band VLF. FBS stands for Full Band Spectrum, but that is still a VLF operating in reality from 12 to 16kHz, just like the Explorers.

VLF stands for very low frequency, generally below 20kHz, not for a sine wave form of transmission.

[crane]

If any ground/rock is magnetic (sticks to magnet) it will always and in every case produce an amplitude and phase shift together.

Why both?

This isn't correct. You are talking about the coupling between the two coils, I'm talking about the receive signal being shifted time wise, similar to the phase shift caused by eddy currents flowing in a metal object. This phase shift can't be duplicated by upsetting the inductance and balance with minerals that are purely magnetic (and don't also produce a resistive or loss component).

A relatively small sample of soft ferrite, or magnetite with similar properties, will change the coil's inductance and the coupling much more than a large copper coin ever will (at depth) but the ferrite doesn't cause a phase shift and the coin does. The ground here can produce a phase shift of up to several degrees whereas the magnetic black sands found in most parts of the world don't produce a phase shift.

A piece of soft ferrite is sometimes used to null the coil. This will alter the amplitude but it won't alter the actual GB setting (phase) in a well built design. That is, if the GB is set to null a particular ground sample, then it won't need readjusting after we change the null point with the soft ferrite. If it does then there is something wrong with the design.

We often hear that soft ferrite, or magnetite with similar properties, can be nulled by centering the demodulator window over zero crossing. This occurs because there is no phase shift and the positive and negative change in amplitude is equal and cancels. In this case the reference is zero volts.
This won't work with our ground because of the phase shift. The GB is instead set up to several degrees from the previous example and the reference continuously changes depending on the phase angle.

If you wish to address complaints regarding GB then surely you would have to be aware of this type of ground???

The CTX3030 is definitely not a vlf and PPS is not the same as frequency. VLF measures the amplitude and phase of the received signal, nothing else.
FBS is a completely different beast as is obvious in the patents and the Minelab white paper.

[Qiaozhi]

We often hear that soft ferrite, or magnetite with similar properties, can be nulled by centering the demodulator window over zero crossing. This occurs because there is no phase shift and the positive and negative change in amplitude is equal and cancels. In this case the reference is zero volts.

This method, of using a small ferrite slug to adjust ground balance on a VLF, is an adjustment that is used in the lab to check that GB is working correctly. The GB control will then normally be at its central position when this is done. However, this setting is only good for non-mineralized soil.

This won't work with our ground because of the phase shift. The GB is instead set up to several degrees from the previous example and the reference continuously changes depending on the phase angle.

As you correctly state, the default GB setting will not work in heavily mineralized soil. Adjusting the GB by several degrees will only work for soil that is relatively homogeneous. This is the reason why all VLF detectors fail miserably in the Australian gold fields.

The CTX3030 is definitely not a vlf and PPS is not the same as frequency. VLF measures the amplitude and phase of the received signal, nothing else.
FBS is a completely different beast as is obvious in the patents and the Minelab white paper.

VLF stands for "Very Low Frequency", and is a general term used for certain types of metal detector. It would be more accurate to split the main types of metal detector into two categories: Continuous Wave, and Pulsed.
The CTX3030 uses FBS (Full Band Spectrum) technology, which is continuous wave. It is not a pulse induction machine in the normal sense, even though it samples the decay curve for at least some period of the pulse train. According to Minelab, the CTX3030 discriminates targets using both ferrous and conductive properties simultaneously. This implies that it's actually a sort of hybrid that measures both phase (to get ferrous discrimination) and decay time (to get the conductive properties).