Field Testing The Whites Mxt W/ 10 Dd Coil
By Chris Gholson
From Page 32
March, 2009 issue of Lost Treasure

Since its release back in 2002, the Whites MXT has become a popular choice for many treasure seekers around the world.
With three preprogrammed search modes, automatic ground balancing, and above average discrimination capabilities, the MXT is an excellent all-in-one detector. It can be used for hunting coins at a local park, jewelry on the beach, relics at an old battlefield, or even for chasing nuggets in the goldfields.
Although I did unearth several coins and relics during the course of my field test, the real purpose was to evaluate the MXT based on its gold-finding abilities.
Before getting too far along, lets take a moment to discuss the controls found on the MXT and how they affect the detectors performance.
MODE This switch is used for setting the MXTs operating mode. There are three preprogrammed options available: Coin & Jewelry, Relic, and Prospecting. In most cases, the user will want to select the appropriate mode for the type of hunting they are doing, however, as I discovered during my field test, some modes can be used for other applications.
TRAC This switch controls the MXTs ground tracking system. There are three options available: Ground, Lock, and Salt. This system, which is nearly identical to that found on the GMT, offers improved resolution and better performance over a wide range of soil types. Plus the entire tracking system can be turned off if the operator wishes.
GAIN Control This knob serves two purposes; it turns the detector ON/OFF and it adjusts the signal strength of targets, ground mineralization, and electrical interference. We will discuss this control in more detail later.
Dual Control In the Coin and Jewelry and Relic modes, this knob establishes the level of discrimination (or trash rejection). In the Prospecting mode, this knob is used to adjust the SAT (Self Adjusting Threshold), which is the speed at which the threshold hum recovers from the effects of ground mineralization.
Threshold This knob is used to adjust the continuous background hum heard while detecting. Threshold adjustment is really a matter of personal preference, however, many users tend to set the threshold as low as possible, similar to the sound of a buzzing mosquito.
Trigger Switch This switch has three possible positions and affects the MXT based on what operating mode has been selected. The Center position is referred to as the Primary Search position. The forward position is referred to as the Alternate Mode position. And lastly, if the trigger is squeezed and held, this is referred to as the Pinpoint position.
Field Test
The area I selected for my field test was both beautiful and well known for its gold production. In the early 1860s, the discovery of the yellow metal in this mountain stream sparked one of the largest rushes in Arizona history. Men flocked from all over the southwest to try their hand at digging up a fortune from the rich gravels.
The region has yielded many hundreds of nuggets over the years and still remains a rewarding place to prospect. However, there is one major drawback for metal detectorists the trash! After more than a century of intense mining activity, the creek bed has been littered with an endless supply of man-made trash. I knew it would be tough going, but I hoped the MXT would be up to the challenge.
Rather than working directly down the center of the creek where the overburden was deepest and trash thickest, I targeted the exposed bedrock and benches. I started off in the Prospecting mode with the Gain in the preset position (between 9-10) and an SAT of 3, with the trigger in the Center position. With the TRAC toggle in the Ground position I pumped the coil atop the soil allowing the automatic tracking to do its job.
The MXT is usually supplied with the Eclipse 950 coil, however I was fortunate enough to be able to test drive one of their newest designs, the 10 Round DD. Weighing in at a mere 17.9 ounces, this coil is exceptionally light for its size.
The open design coils do have a tendency to become hung-up on branches and grass, but, for me personally, the reduction in weight far outweighs the inconveniences of these snags. Less weight means less fatigue and ultimately more time swinging the detector.
The 10 DD offered excellent ground coverage, crisp pinpointing along the center, and I was pleased to discover it had absolutely no trouble handling the ground mineralization. In fact, I was able to increase the Gain to the +1 mark without experiencing Threshold instability.
There were a lot of targets to contend with, so I followed the advice given in the instruction manual and set the TRAC to the Lock position. I hunted in this mode for most of the day and accumulated an assortment of both old and modern day garbage, but, unfortunately, no gold. The MXT performed surprisingly well in this soil. It was not the most extreme I have encountered, but neither was it mild. Even with the Gain set in the + zone I had no trouble distinguishing true metallic targets from background noise.
Choosing the proper setting for the Gain is not always easy. The first impulse many people have is to increase the Gain, believing this will actually pump more power into the ground. In reality, the Gain only controls the sensitivity of the received signal; the transmit power uses a fixed setting.
So, turning up the Gain wont send out a bigger field, but it will impact your detectors performance. In bad ground, a high Gain will cause the detector to become noisy, signals will sound distorted, the Threshold may disappear, and overall performance will suffer. In quiet ground, a high Gain setting will greatly improve signal response on both small and deeply buried nuggets.
It must be remembered that the Gain and SAT work in conjunction. Changes made to one will affect the other, so compromises must be made. When in the Prospecting mode, the ideal settings would be a very high Gain with a very low SAT.
This would be ideal, but not realistic, especially in highly mineralized regions such as Australia and parts of the southwestern U.S. A higher Gain improves overall sensitivity and depth, but will require a higher (or faster) SAT speed. Faster SAT settings offer a more stable threshold, but will in turn reduce both sensitivity and depth penetration. See what I mean about compromises?
When detecting extreme ground, one possible option would be the HyperSAT. As the maximum setting on the SAT control is approached, the MXT goes into HyperSAT, which is a completely different type of SAT system with different sounds and target responses. In this setting the threshold becomes more jittery, but it will help smooth out ground noise and reduce, or even eliminate many negative hot rocks.
In most cases, I would opt for using the traditional SAT unless an area of extreme ground mineralization. If you find yourself having to run a Gain of 7 or less, it would definitely pay to experiment with the HyperSAT setting. In any case, the ultimate goal is to achieve as smooth and steady of a Threshold as possible.
The following day, I returned to the same site to test the gold-finding ability of the MXT in the Relic mode. Once again, I set the Gain in the preset position and the TRAC toggle in the Lock position after balancing. Unlike the Prospecting mode, the Dual Control does not set the SAT speed, but rather adjusts the level of discrimination.
Over the years, I have learned that higher discrimination levels usually equate into less depth penetration. I wanted to set the discrimination level as low as possible, yet still high enough to be effective on ferrous trash. To do this, I waved a 2 rusty nail across the coil and slowly increased the Dual Control knob. At a setting of 3, the nail gave a distinctive low tone and a VDI number of -41. In no time at all, I was able to distinguish between ferrous and nonferrous simply from the tones.
I did run across a number of hot rocks, but these were generally easy to identify by their double boing sound and a VDI reading of -95. While trying to pinpoint one, I found that if the trigger was squeezed and the coil held stationary over the hot rock, most would null or go away, whereas true metallic targets always remained solid. A simple, but effective test.
Several hours into the day, I waved the coil across a stretch of exposed bedrock and received a very powerful low tone. A quick check of the VDI confirmed that the target was likely iron. Out of curiosity, I scratched away a few inches and exposed an orangish-colored object lodged within the crack. The MXT had identified this target correctly; it was a chunk of iron pipe.
Before filling it in, I swung back over the hole and received a much fainter, but high tone signal. In the Prospect mode I would have dismissed this signal as being a fragment of the deteriorated pipe, but in Relic mode it consistently gave a high tone and a VDI of +28. Using the tip of my pick to further open the crack, I spotted the source of the noise. The pipe had been concealing a shiny 2-gram nugget!
Encouraged by my first MXT gold find, I pushed further up the creek. I worked the rest of the bedrock and added a few more targets to my pouch, but none of them yellow.
On an inside bend I encountered an area where the old-timers had obviously struck gold. The bench was covered with small tailings piles and, unfortunately, tin cans. I knew no detector on earth could sort through the mess, so I spent the next 15 minutes clearing away the cans by hand. Many of them had decomposed and left fragments scattered throughout the soil. Luckily, the small bits, which can be most distracting, tended to give off a low tone.
The bigger scraps produced a high tone, but were easy to spot in the dirt and quickly picked up with my magnet. I learned that iffy high tone targets should be investigated from two ways. I also found that it was necessary to scrape away an inch or two of soil from targets which gave complex signal or mixed reading on the meter.
From the bench I dug several Levi buttons, a few clad coins, a large buckle, and some bullets before I caught my next glint of gold. At 3 down the signal was faint, but it gave a consistent high tone and a VDI reading of +24. Although this nugget was slightly smaller than the first, I was in no way less pleased. With the spot price of gold sitting around $850/oz., my MXT had just made me $70 for the day!
In order to get the best possible performance from the MXT, or any metal detector, an operator must be open to experimentation. They will need to flip switches, twist dials, and use the equipment in a variety of different locations before making up their mind on what works best.
In the MXTs case, the operator will need to use whatever Mode best suits their needs despite what the program may be called.
For example, at first glance the Prospect mode would seem the obvious choice for the nugget hunter. And, indeed, it is a powerful option that offers better sensitivity than the other modes. However, I did not find this mode nearly as effective as Relic for working heavily trashed sites.
The iron grunt and % Iron Probability available in the Prospect mode are good concepts, but not always reliable. Many targets I found at depth sounded nearly identical, and those made of iron would only produce a reliable grunt when in close proximity to the coil.
The % Iron Probability was fairly accurate, but, even still, I did not find it nearly as easy to use as the 2-tone system of the Relic mode. With the trigger in the center position, the detectorist will not have to constantly look at the display; he/she can quickly sort ferrous from nonferrous by simply listening to the tones. Low tones are bad and high tones are good too easy!
Some of the areas I think hold the best potential for this mode are mine dumps, placer diggings near old camps, creeks and washes full of rubbish, and especially in dredge tailings where mineralization is low and nuggets are likely to be large.
Here are some other miscellaneous notes that might be of interest. The MXTs tracking system works very well - sometimes too well. If the TRAC toggle is set in either the Ground or Salt mode, the user should not hover over the top of a suspected target otherwise the analysis engine may try to track it out. This only seems to happen with very tiny or deeply buried targets. Any target strong enough to register on the VDI will tell the analysis engine to halt, allowing it to be checked without fear of tracking it out. The user can also manually halt the tracking at any time by squeezing in the trigger, or by operating with the TRAC in the Lock position.
In Relic mode, if the trigger is pushed forward the MXT will blank out ferrous targets. If trash is abundant, this setting is easier on the ears, however, I noticed that the Threshold became unstable and the overall quality of sound was diminished.
I also discovered that with a forward trigger and a maximum discrimination setting, the MXT would actually blank out a small nugget! We all want to eliminate as much trash as possible, but not if it means passing up gold in the process. If you use the forward trigger position, you may need to reduce the Gain and stick with lower discrimination levels. My preferred settings for the area I worked were Mode = Relic, Gain = +1, Discrimination = 3, Trigger = Center, Trac = Lock.
My overall impression of the MXT was positive. Even if I had not found a single piece of gold during my testing I still would have been impressed. When comparing to other VLF detectors in the same price range, it ranks right up there at the top.
This is an incredibly versatile machine that will certainly appeal to a wide range of detectorists. At 14 kHz, the operating frequency is high enough to be sensitive to gold nuggets, low enough to give a good target ID, and halfway in between power line harmonics which helps reduce electrical interference - a widespread problem in the US. Another benefit of this frequency is that it makes the MXT compatible with search coils designed for the DFX.
There are other brands of specialty gold detectors which utilize Pulse Induction technology and are able to penetrate twice as deep and eliminate even the harshest ground mineralization, however, they cost several thousand dollars more and, truthfully, their ability to weed through trash pales in comparison.
The MXT is a wonderful choice for budget minded persons seeking their first metal detector or for those more serious individuals as a back-up machine for working high trash locations. Testing this detector with the 10 DD was a pleasure, and I am confident more golden finds are in store for me and the MXT.
For more information on this product, visit the manufacturers website at or call them at 1-800-547-6911. Be sure to tell them you read about it in Lost Treasure Magazine!

Field Testing The Whites Mxt W/ 10 Dd Coil

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