A
Anonymous
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Hi All,
The question has arisen about the White's MXT and how it might compare to a PI such as Eric's GQ. Well, some very brief testing was done my last trip to AZ shortly after I found my two smaller gold nuggets.
Basically, the test was done using the smaller of the two very small nuggets I found at that site. This test was an "air test", meaning the nugget was placed on the ground and then passed over using both the PI and the MXT. The basic test was to compare signal strengths, as well as observe the VDI reading of the MXT.
One should realize that this was a very limited test but the basic information should be of value, expecially when trying to use either detector for nugget hunting.
The MXT was equipped with the new small DD coil (maybe 3" by 6" size). My PI was equipped with an 8 1/2" by 11" DD coil.
First, the MXT did show a stronger signal to the smaller of the two nuggets (the one just over 1 grain in size). Air testing indicated maybe an inch or so depth increase was possible with the MXT. However, the MXT also displayed a 30% chance the known object was gold when the coil was a couple inches or more from the nugget. It wasn't until the coil was quite close to the nugget that probability that the nugget was gold, increased to 70%.
Increasing the delay a little on my PI quickly eliminated the signal from the gold, indicating the object was a low conductive object.
This simple test mainly displays that a VLF could easily be a better choice for the detection of very small nuggets, maybe in the size range of less than 5 grains or so.
However, I wanted to point out the problems that could be encountered using a form of discrimination on a VLF to determine whether a small object is gold or not.
The PI, on the other hand, provided a more accurate indication, using the delay method on the very small nugget.
I would like to point out one other important fact, that although I didn't get the opportunity to try the MXT on my largest nugget found (3/8 oz), I would have expeced the MXT to be more accurate in an air test.
I can say that this larger nugget did provide a reduced but still strong response when I checked the object on my PI using the delay method before it was actually dug. So, one should realize larger nuggets can easily generate a signal even using the delay method of discrimination on a PI.
As a basic conclusion, one should heed what has been written before, that the only true accurate discrimination is the visual method, and that is to dig up the object and visually note what it is.
In the case of the MXT owner, he was somewhat surprised when the MXT only gave a 30% probability the nugget was really gold when the coil was elevated. Having more experience with discrimination circuitry, this low reading didn't surprise me. I would expect many of the weaker signals to display inaccurately, not only on the MXT but any other VLF with discrimination capabilities.
As for the PI producing a response on my larger nugget with a longer delay, that didn't surprise me either, since previous experimenting had indicated very solid nuggets in the 1/4 oz size could produce a reasonably strong signal with a longer delay. Had I relied solely on using the longer delay method of discrimination, I might have left the larger nugget behind.
Just food for thought, but hopefully, it points out the need for a lot of experimenting to better understand what might happen in the field. One should always remember that discrimination circuits are not perfect.
Reg
The question has arisen about the White's MXT and how it might compare to a PI such as Eric's GQ. Well, some very brief testing was done my last trip to AZ shortly after I found my two smaller gold nuggets.
Basically, the test was done using the smaller of the two very small nuggets I found at that site. This test was an "air test", meaning the nugget was placed on the ground and then passed over using both the PI and the MXT. The basic test was to compare signal strengths, as well as observe the VDI reading of the MXT.
One should realize that this was a very limited test but the basic information should be of value, expecially when trying to use either detector for nugget hunting.
The MXT was equipped with the new small DD coil (maybe 3" by 6" size). My PI was equipped with an 8 1/2" by 11" DD coil.
First, the MXT did show a stronger signal to the smaller of the two nuggets (the one just over 1 grain in size). Air testing indicated maybe an inch or so depth increase was possible with the MXT. However, the MXT also displayed a 30% chance the known object was gold when the coil was a couple inches or more from the nugget. It wasn't until the coil was quite close to the nugget that probability that the nugget was gold, increased to 70%.
Increasing the delay a little on my PI quickly eliminated the signal from the gold, indicating the object was a low conductive object.
This simple test mainly displays that a VLF could easily be a better choice for the detection of very small nuggets, maybe in the size range of less than 5 grains or so.
However, I wanted to point out the problems that could be encountered using a form of discrimination on a VLF to determine whether a small object is gold or not.
The PI, on the other hand, provided a more accurate indication, using the delay method on the very small nugget.
I would like to point out one other important fact, that although I didn't get the opportunity to try the MXT on my largest nugget found (3/8 oz), I would have expeced the MXT to be more accurate in an air test.
I can say that this larger nugget did provide a reduced but still strong response when I checked the object on my PI using the delay method before it was actually dug. So, one should realize larger nuggets can easily generate a signal even using the delay method of discrimination on a PI.
As a basic conclusion, one should heed what has been written before, that the only true accurate discrimination is the visual method, and that is to dig up the object and visually note what it is.
In the case of the MXT owner, he was somewhat surprised when the MXT only gave a 30% probability the nugget was really gold when the coil was elevated. Having more experience with discrimination circuitry, this low reading didn't surprise me. I would expect many of the weaker signals to display inaccurately, not only on the MXT but any other VLF with discrimination capabilities.
As for the PI producing a response on my larger nugget with a longer delay, that didn't surprise me either, since previous experimenting had indicated very solid nuggets in the 1/4 oz size could produce a reasonably strong signal with a longer delay. Had I relied solely on using the longer delay method of discrimination, I might have left the larger nugget behind.
Just food for thought, but hopefully, it points out the need for a lot of experimenting to better understand what might happen in the field. One should always remember that discrimination circuits are not perfect.
Reg
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