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MXT FAQs

Rudy

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Joined
Jan 10, 2006
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Location
Beaumont, CA
MXT Frequently Asked Questions
Compiled & written by Chris Ralph (Reno Chris)
Permission to re-distribute Chris’ FAQs obtained by Rudy of the
Friendly Metal Detecting Forum​

1) I just got my new MXT. I am wondering what should I do first?

One of my High School teachers was often fond of telling students with questions – "Read the directions carefully!"
That saying applies just as well to the new MXT owner. Read and re-read the owners handbook before you take your
MXT out for its first use. It contains many helpful suggestions that can prevent unnecessary problems.

The Engineering Report, written by the design engineer for the MXT, also is worthwhile reading, and contains some
useful information which the Owners manual does not. Both the Operators Manual and the Engineering Report are
available over the internet on the White’s web site, or can be purchased in print from Whites. Take a look at the MXT
video too, if you have a copy. It doesn’t have a lot of critical information that can’t be found elsewhere, but its worth
watching.

After watching and reading, take your MXT out into your yard and do some testing. Put a coin on the grass and see how
it responds to it. Look around your own yard - many older homes have older coins in the grass. If you damage your own
lawn while digging, well, at least you know who to complain to.

2) I am ready to take my MXT out into the field. Any suggestions on how I should practice with it?

Plant a couple of coins in the sand at a park and practice finding, pinpointing and digging them. If you are new and
having trouble with pinpointing and finding targets, try digging in the sand or wood chip areas of the playgrounds.
If you have to dig a 10 inch diameter crater to find the coin, you will find it easy to fill in and no grass will be killed
if you dig in the sand. Usually there is a lot less trash there as well. Later when you are more experienced and can
dig small holes to recover your targets, try out the grass. Always fill in your holes - I have been accosted by a local
park ranger simply for possessing a small hand trowel (and a detector) at a local park. Someone else had been digging
big holes and killing grass a week or two before, and as soon as he saw me, I was automatically guilty of the same crime.
They go to lots of effort to keep a nice lawn at the park. We all need to be mindful of the disturbances we make and
take due care not to make a mess. Its important to do what we can to stay in the good graces of the local park staff.

When you are new with the MXT and find a good target take your time with it to learn how the machine reacts to it.
Listen to the sounds. See what the ID says about it. Once you have learned the machine and are comfortable with it,
you don’t need to analyze the target to death, but when you are a newbie, there is a lot to learn from testing things out.
Learn all you can from each find! Try flipping the unit into another mode (try going into Relic or prospecting if you are
normally hunting in Coin/jewelry) to see how that mode works.

Here is an valuable secret on how to become a productive detector operator (even if it seems obvious): The big key to
getting the most out of your MXT is practice. Studying the manuals and other information will help shorten your
learning curve, but it just takes time. There is no substitute for practice time - experience allows you to know exactly
how your machine responds to certain kinds of targets. You will be much better after digging your 2,000th coin that
you were when digging your second coin. So read all the information you can get your hands on, and then get out
there put in the time to learn your MXT. Practice, practice, practice - the more time you spend, the more confident and
comfortable you will feel with your detector, and the more good stuff you will find..

3) Does the meter really help much in deciding whether to dig a target or not?

The MXT has an excellent target ID system. Learning to use it is one of the first priorities of the new MXT user
(See the VDI score ID chart in this document a few questions down). The most important thing to remember is that
the ID systems only are accurate when you are passing the middle of the coil right over target (or very close to it).
So use the pinpoint to find the target before making a final ID (and decision to dig or not). Sometimes in trashy areas
the effects of nearby targets can be misleading. Many iron targets have a halo, and if you pass the coil a few inches
away from the target, not over the center, you can get a false "good" response - even to the point, at times, of getting
a full probability bar. Finding the true center of the target and then passing the coil over it for an ID will give far more
reliable results. Also, when pulling the pinpoint trigger to locate a target, be sure the coil is not over another target at the
time. Being over a target then pulling the pinpoint trigger can give weird and unexpected results, so pinpoint over clean soil.
Unfortunately, in spite of all these efforts, a few types of iron targets just seem to be especially good at fooling VLF ID systems
- this goes for all brands of VLF units, not just Whites. Iron washers and steel bottle caps are the chief culprits among
these bad boys (Note from Rudy: Search for my post on dealing with "pesky bottlecaps").

Its also important to note that the target ID is not accurate to the full depth of detection. The engineering manual says
the ID is only accurate to about 3 inches. I have found it to go far deeper even in my mineralized soil, and my experience
is that it is accurate to at least 5 inches, but it is not reliably accurate to the full depth the MXT can reach. In some areas,
the iron content of the soil can cause a shift of the target VDI numbers on deeply buried targets, usually dropping them l
ower than would be expected. Nickels can shift to the foil range, cents to the pulltab/screwcap range, etc. It is also
important to note that the target ID will not work as deep as the detector will detect. In areas where there are likely deep,
older targets present, it is probably necessary to dig all deep non-iron targets - or miss good finds. This especially includes
deep targets that are repeatable, but give no VDI reading at all. Because the very best finds are often the deepest ones,
deep non-iron or even no VDI targets should be investigated and there is a good chance that these targets might produce
old coins, or other valuable finds. Deep targets that do produce a VDI score can bounce around significantly, and they
often do not "lock in" as well as targets nearer the surface.

4) How does adjusting the discrimination setting affect the meter readings on the MXT?
An interesting feature to note about the MXT's ID system is that the discrimination setting does not affect the display
output. This is not mentioned in the book or the video. No matter the discrimination setting, the VDI and probability
bar output are exactly the same. The discrimination setting only affects the sound output. The engineering guide for
the MXT states that the visual ID is a bit more accurate than the audio discrimination in most cases. I have found that
the best results occur when I use all the information available - gauging in my head both the sound output as well as
the meter display. It takes a bit of practice, but is worth it. It is possible to find targets that are within the audio
discrimination setting. I have found nickels using the display only when I had the discrimination cranked up nearly to
the max. by observing the output on the meter, specifically the VDI meter. All three of these ID systems (target
response sound, the VDI/potential ID, and the probability bar) are independent and all 3 should be considered in
deciding whether or not to dig a target. It is good experience to learn to use that probability bar - it helps a lot in
trashy areas. Whenever you get a high probability bar indication, it is pretty reliable. The high reading will usually
be correct, or something very similar (I have gotten a full bar quarter reading over a penny that was probably buried
at least 20 years - though nearly all other consistent full bar quarters I have dug while coin shooting were just that
- quarters).

Another thing to note about the discrimination is that when the setting is zero, you do have true zero discrimination
- no disc at all. This is important to know when prospecting for nuggets or beach hunting for earrings.

5) The target ID on my MXT seems so much more jumpy than other detectors I've used. Why?

Many detectors (including many by Whites) average the readings when you make multiple passes over a target.
The MXT does not - with the MXT if you make 10 passes, you get 10 different independent readings. This is why the
MXT seems to be more jumpy on target ID than most, if you are not used to it. Good targets usually give pretty
consistent non-iron indications. Iron and irregularly shaped junk targets like pull tabs usually jump around and are
inconsistent on the MXT ID system. Foil usually jumps around a lot too as it is usually oddly shaped. If you make
4 passes over the target and get 1. quarter (with low probability); 2. Iron, with high probability; 3. $1 with low
probability; and then 4. Iron; then the target is almost certainly rusty iron junk.

If you get some consistent good readings in trashy areas, it might be a good target close to junk. Try to isolate the
good target by moving the coil back and forth in different directions.

6) I'm having problems with my MXT in trashy areas. What can I do?

Mixed junk and good targets in the same spot can cause all kinds of problems with the MXT ID system because the
coil can have 2 or more targets underneath it at the same time - so it combines readings from both. This is true for
all VLF detectors and is why some areas like the trashy parts of parks, etc. can be the most productive - no one else
wants to hunt there.

If there is at least a little space between the targets, most of the time iron junk and good targets within a few inches
of each other just makes the readings inconsistent. Sometimes a target will read one thing sweeping from one direction,
and read different on the return sweep coming from the other direction. This all makes it real tough to decide dig / no dig
in trashy areas. Making use of the smaller MXT coils is probably the first recommended adjustment to working in trashy
areas. The small coils are very useful in separating junk from good targets in trashy places - and the difference is significant.
The smaller coils can sometimes find targets that are completely masked by iron junk close to the target. The 5.3
concentric would be best for coin shooting in trashy areas with low to moderate soil mineralization, the 4 x 6 DD is probably
better in higher mineralization soils.

One technique that I have learned to try is turning 90 degrees and making a second set of sweeps in an X pattern over the
target if I am uncertain. This technique is mentioned on the Whites MXT video, but not in the manual. Sometimes a junk
target will indicate consistent penny or $1 with but always with lowest probability. Do the 90º turn make another set of
passes from a different direction. If the target indicates better, dig it. If it jumps around and shows iron or hot rock,
move on. The 90º turn makes a big difference sometimes. In trashy areas, one can use the VCO pinpoint to find the
location of the nearby targets, then choose lines of direction to pass over the targets without passing over multiple ones.
Except for a few real deep targets, it is rare that a target will read "iffy" in multiple directions. As far as the deep targets,
when working areas where older targets may be present, probably any target at 6 inches or deeper giving consistent
non-iron readings ought to be dug. This will lead to digging a little extra trash, but also will lead to some fantastic finds.

7) How do various kinds of targets sound in the VCO pinpointing mode?

Coins and other non-ferrous (not magnetic) targets tend have sharp pinpoints and go from nothing to max to nothing very
quickly, over a short distance. Iron junk tends to have large broad pinpoints as if they were much larger than they are
- they go slowly up to max and then down - a rusty bolt will act as if it were as big as a coffee can to the pin pointer.
The pinpoint trigger can be used to help ID targets. This same difference in the MXT's response can be noted in regular
operating modes as iron is said to sound broader or mushier, and the sound of coins or gold is said to be sharper or more
peaked. However, the effect is more easily noted in the VCO pinpoint modes.

8. How accurate is the depth reading in the VCO pinpoint mode?

The depth reading is excellent if the target is a coin or coin sized and fairly close to the surface. At the maximum detection
depth of the MXT, the estimated depth readings are not as accurate. Remember that the depth reading on the meter
assumes a coin sized object - if smaller, the target will be shallower, if larger than a coin, the target will be deeper.
I regularly hunt a park where there is a buried brass head sprinkler system at about 4-5 inches. These brass heads sound
out clear as a quarter and read on the meter as being at 0 depth. However, although they pinpoint sharply like a coin, they
also pinpoint much larger than a quarter. It takes about 2 seconds to shove my screwdriver in far enough to find a large
object at 4-5 inches, then I know its a brass sprinkler (I've dug enough of them to know). It is safe to say that if you've
dug a 4 inch hole for a target that is supposed to be at 1 or 2 inches, and the hole is correctly centered over the target, that
the deeper target is much larger than the coin indicated. On the other hand, a target smaller than a coin will usually be
found shallower than the meter's depth indication.

It should also be noted that the depth reading is calibrated to be correct when using the stock 950 coil. If you are using a
different coil, the depth reading will be off.

9) I am having problems in the VCO pinpoint mode. Any tips for a better technique?

With the 950 concentric, most targets, including coins, make a significant tone change when the target crosses over the
edge of the inner opening of the coil. It is easy to get the target under the inner opening based on the tone, and after
that one can find the exact location by doing an X pattern over the target and listening for the sound change when the
target passes across the inner edge - out of the opening and under the coil. This technique can be used to both locate
a target as well as measure its size. Using this technique, I can usually find a near surface coin on the first try with my
probe - if I don’t hit it on the first try, I am usually not far off.

The DD coils are a bit harder to pinpoint with, but still not a problem. The sensitive area under a DD coil is blade shaped,
so by making an X pattern over the target, it is possible to pinpoint a target using the DD to a fairly tight area. When
pinpointing with either the DD’s or the concentric coils, practice is the key to accuracy.

10) Can my MXT tell the difference between coins or gold rings and pull tabs or other trash?

No discrimination system on any detector is perfect. There are always tradeoffs in any target ID system design, and
although the MXT ID system is as good as any available today, it can be fooled and it cannot always differentiate between
some types of targets and some types of trash. The discrimination readings are influenced principally by the target
shape, size and conductivity of the metal. As an example, nickels, some pull tabs and rings all appear the same to VLF
type metal detector’s ID systems. Most men's wedding bands and ladies gold rings read in the 10 to 30 range in my soils.
The lower end of that range includes junk foil, and the upper end includes many types of pull tabs and cut up bits of aluminum
cans. Larger men’s rings and "class" type rings usually read in the 30 to 53 range – same as the square pull tabs.
Nickels usually read in the 18 to 22 range in my area soils, but there are exceptions. Some oval shaped pull tabs read
consistently in the nickel range - but I find near surface nickels sound "sharper" and pinpoint tighter (smaller) than pull tabs.
Silver rings are usually not ignored by detectors as they usually read in the dime to quarter range. Certainly when you hit a
target with a VDI number between 30 to 55 it is almost always going to be a square pull tab or aluminum screw cap, but not
always - once in a while those targets might be a large gold ring and you would be losing a potential great find. You just can’t
get around it - if you ignore the targets in that VDI range, you are ignoring some nickels and rings as well as those pain in the
neck pull tabs. Turn up the discrimination too high and you will miss gold rings. However, in some very trashy areas, you can
dig 10,000 pop tops and pull tabs to every gold ring. If that’s worth it to you go for it - its your decision. The key for me has
been deciding what I will do based in my location. Picnic areas in parks are overloaded with pull tabs, but not as many rings.
Sports fields have more rings and usually fewer pull tabs. I recommend choosing yourself, based on the type of site, when
you will or will not dig all targets in the pull tab range. In sites which have been abandoned since before the pull tabs came
out (in the early 1960’s) you want to be sure to dig any signals in that range, because there should be few and there is a
significant chance of a valuable target. The following chart gives VDI ranges for some typical targets (a chart like this should
have been in the MXT user’s manual in my opinion). Degrees of corrosion, soil iron, nearby junk and other factors affect the
VDI readings, so these are not carved in stone, but will give you a good idea of what you might find in each range.


VDI Range Some Possible Targets found in this VDI Range:
-95 to - 20 Antique iron relics, Iron nails, rusty iron junk, hot rocks
-20 to 0 Small gold nuggets, gold earrings, gold chains, small bits of iron, gum wrappers, small bits of foil
0 to 15 Platinum rings, smallest gold rings, gold earrings, gold nuggets, sterling chains, larger foil pieces, gum
wrappers, bits of chopped aluminum cans
15 to 30 Most gold rings, Gold nuggets, Gold $1, Nickels, oval pull tabs, bent tabs, bits of chopped aluminum cans,
zipper tabs
30 to 45 Largest gold rings, larger gold nuggets, Gold $2.50, Copper Nickel cents (1856 to 1864), Silver War Nickels,
most square pull tabs, iron bottle caps, small aluminum screw caps, Costume jewelry
45 to 60 Gold $5, Corroded zinc cents, 3 cent silver, zinc pot metal junk, costume jewelry, brass keys, small aluminum
screw caps
60 to 70 Indian Head Cents, small sterling earrings, zinc cents, hot wheels cars, larger aluminum screw caps
70 to 78 Gold $10, modern copper cents, half cents, two cent pieces, small sterling rings and sterling jewelry, hot
wheels cars
79 to 81 Gold $20, sterling silver rings, clad or silver dimes
82 to 88 Clad or silver quarters, heavy sterling silver rings, Sacajewea "golden" dollars, SB Anthony dollars, buried
brass sprinkler heads
89 to 92 Clad or silver halves, large cents, buried brass sprinkler heads
93 to 94 Clad Eisenhower or silver dollars, large copper pipes


11) My MXT is noisy in wet sand on saltwater beaches. How can I improve its performance?

On dry sand, there should be no problems. There can be noise and chatter issues in wet sand and with the head
underwater. On a low mineral beach soil, the MXT may operate just fine in wet sand. However, on beaches with
significant iron content, the MXT must adjust both for any iron sand or rocks in the soil, as well as the salt. Unfortunately,
black sand and salt balance out on opposite ends of the scale, so it is hard to adjust for both at the same time. The
standard 950 concentric coil is fairly sensitive to mineralization. If there is any iron, any variance in conductive soil
moisture, or if the coil head actually goes under water, this will cause the coil to make lots of noise. The ground
balancing switch needs to be set in the "salt" mode for these conditions, but most users find they also need to switch
to one of the DD coils to get the best results on the wet sand when the sand has some iron mineralization present.
The DD coils are less sensitive to the salt or iron mineralization than the standard 950 concentric. The last option in these
conditions is to turn up the discrimination (usually not desirable since beaches are prime ring hunting areas and it is easy to
lose potential finds turning up the discrimination too high) or to reduce the gain which still allows ring detection, but lower
gain reduces the depth at which a target could be detected.

12) What happens if I turn the gain down below the recommended preset level?

The MXT is a high gain unit, made to be able to find small gold flakes. When you are just coin shooting, you can turn
the gain down some (say to about 7-8) with no big problems if you are willing to blow off the deepest stuff (hey, you
don’t need to worry about those 6 inch deep barber dimes when you are hunting at a school built in 1972 on a clean
site). When you are new to the machine, try dropping the gain to 8 and then cranking the discrimination up to about 7
to eliminate most trash. You can increase the gain and lower the discrimination later as you get to know the machine
better. However, the deepest detection (of coins, etc) and the detection of the smallest objects (small nuggets, small
earrings) require the highest gain. Unfortunately, the highest gain also means the greatest noise from the MXT.
For ways to deal with that noise, see the noise question -#18 - below.

13) I took my MXT out and it was acting strangely. I noticed one of the switches had been bumped.

One thing I have noticed it that it is easy to accidentally bump a switch and change a setting while putting the MXT
away or getting it out. Every time you take out your MXT and turn it on, check to see that all the switches and knobs
are set exactly where you want them.

14) I was testing a target and it just disappeared. A few seconds later it was back. What gives?

When you are in automatic ground balance and making multiple passes over a target to ID it, be careful not to stall
over the target and let the system track into the target and adjust the ground reading to include the target. This can
give bad or unexpected results. The auto ground balance adjusts quickly and may adjust out a target faster than you
might expect.

15) How can I tell what the mineralization level of my ground is? What does it mean?

Here is how to use your MXT to determine your relative level of soil mineralization. When you are out hunting, flip the
MXT into prospecting mode when the coil is over some target-free soil. In the upper right hand corner there is a label,
GND = 78 (or some other number). The ground reading number tells you what the MXT is seeing as far as soil
mineralization. If your number is 30 to 50, you have low or no mineralization (lucky you!). Readings of 50 to 69
are found in moderately mineralized soil. A reading of 70 or over is highly mineralized soil. In general, highly
mineralized soils are much harder to hunt in, often tend to have more hot rocks and as a result are noisy to hunt over.
Some areas with moisture and a high alkali or salt content can cause their own set of problems. They read very low on
the ground scale and give ground readings in the 20s. The MXT has a separate salt adjustment on the ground balance
settings for work in these areas.

Soil mineralization that reads high on the ground scale is caused by iron minerals in the soil, and can have a very significant
negative effect on the operation of your detector. Unfortunately for us detector operators, the earth's crust averages a little
over 8% iron and some of us seem to have a just a bit more than our share! This is why all modern VLF type detectors have
the ability to adjust and compensate for increased iron in the soil. The automatic adjustment the MXT makes to compensate
for mineralization is not just a simple reduction of gain, but the net result of ground balancing to hunt in highly mineralized
soil is reduced sensitivity. Reduced sensitivity means reduced target detection depth. The MXT (and all other VLF type
detectors) will detect much deeper in dry sand that reads 40 on the MXT ground scale than it will in soil that reads in the low
80s. There are a number of factors that affect target detection depth, including soil density, soil moisture, salt content, and
others. Soil mineralization is just one of these, but it is one that is common, and does have a significant effect.
Here in the Reno, Nevada area, soils typically vary from the high 70s to low 80s.

16) My MXT wont get as much depth as others claim for it. Why?
This is actually a very complex question, as lots of factors can negatively affect detector depth. Iron mineralization in
the soil is one of the most common, but soil moisture, soil salt content, soil density, and nearby power transmission lines
can also affect depth. The settings on your detector and the strength of your batteries can also affect your depth of
detection. The deepest depths are usually obtained in dry, non-mineralized sand (or with air tests - no soil at all!).
To get the greatest depth, generally the gain must be at its highest setting, +3. The prospect mode of the MXT actually
gets just a bit more depth than the other two operating modes. In all modes, deep signals are weaker and can take some
experience to recognize. The bottom line is that many of the factors that determine depth, like mineralization, cannot be
easily changed – they are characteristics of the site you are hunting. Learn to use your detector to the best of its capability,
and you will get the best depth possible at that site with that equipment.

17) Sometimes I find "ghost" targets that disappear when I dig them. Why?

Luckily, ghost signals that are repeatable in more than one direction are not that common. So one good way to eliminate
a lot of them is to test weak signals from more than one direction in an X pattern. This can eliminate a lot of unnecessary
digging. Even so, ghost targets still occur once in a while. Because of its high gain, the MXT may be a bit more susceptible
to these ghost targets than most detectors. Groups of a few small iron bits close together can sometimes cause these - when
dug, the group is separated and the apparent target disappears. Tree roots with higher salt content than the soil can show
up as good targets that are not really there as well.

18) My MXT seems a lot noisier than other detectors I have owned. Why is this?

There are very few complaints about the MXT, but one of the few that is regularly heard from new users is that the unit
is too noisy, chattering and chirping on tiny bits of hot rock, foil and soil iron. These folks would strongly prefer a detector
that is just silent until an acceptable target is found. This situation is most often noted in strongly mineralized ground.
Most of the MXT's ability to get deep items or small gold nuggets is due to its higher than normal gain (and the circuitry
to handle that higher gain). This higher gain, the fact it does not average passes over targets, the greater operating KHz
of the MXT, plus some other features of the detector, do make it more chattery than most. Dave Johnson, the design
engineer for the MXT (and a very talented one) spells out why the MXT makes more noise than most detectors in his
engineering report. In the simplest terms, the increased noise of the MXT is the trade off for the increased sensitivity,
both to small targets (nuggets) or deep targets (old coins). However, even in very highly mineralized soil, I have found
that with the right adjustments, I can get used to the chatter and pick out the coins, other good targets, etc.
The two tone feature of the relic mode also works real well for this type of situation. The relic mode is best used in these
situations by setting the discrimination at just a hair under 4 (or higher where appropriate) and pushing the handle trigger
forward. This makes the low (iron) sounds go away, the general noise becomes a medium tone (same as the normal tone in
coin mode), and the good targets are the high tone. this makes it easy to ignore the medium tones and focus on the highs.
It definitely takes some time and practice, but one can get used to it. There are also some other techniques that can help
reduce the noise, though none are a perfect answer. Locking the ground balance over clean soil can help, especially in areas
where a large amount of man made iron trash is present, such as at ghost town sites. Use earphones with adjustable sound
settings, and turn them down until it is not painfully loud when pinpointing over a near surface target. Using DD coils rather
than the standard 950 concentric also helps quite a bit as the DD design is less sensitive to soil mineralization as a whole.
Unfortunately, the DD coils are also a compromise as they get slightly less depth than the 950 concentric coil. The threshold
sound level can be turned down a bit below the edge of hearing, and this helps a small amount, but the real problem with
noise is in the gain. Although turning down the gain will cut down the noise significantly, it will also significantly reduce
depth and sensitivity. In order to get those deep coins others have missed, or to pick up those small nuggets, the gain needs
to be up at +2 or +3. So to get the full performance from the MXT one needs to learn to get used to the chatter and learn
to pick out those good targets from the background noise. With practice and a little tweaking, one can find the best balance
of coil and other adjustments to make the targets as distinct as possible from the background chatter. The goal is to get the
target response that is easy to distinguish from background noise. This means that sometimes, a little less gain can actually
give a better response, as the soil noise will not obscure the weaker target responses. You have to test to see what works
best at a particular site.

For a new user, I'd turn the gain down to about 8, and discrimination up to about 6 for a while when you are first learning
the unit. That makes a huge effect to reduce the noise, and you'll still have no problem getting coins within 5 inches of the
surface. After you get a little more practice, you can turn the gain up and disc. down to get the full performance from the
MXT.

19) What is the best operating mode to choose when using the MXT?

There really is no one best mode for the MXT. There are 3 completely different programs, and the three modes are there to
give you pre-made programs for a wide variety of conditions. The MXT performs quite differently in each mode. The prospect
mode goes a hair deeper, but is the least stable toward ground noise or iron junk, so it is the worst choice for working trashy
areas like parks. The prospect mode has an iron ID feature, but does not have a true discrimination setting. In Prospect
mode, iron trash is dealt with using the iron grunt tone and the interpretation of the screen output by the operator (only the
Relic and Coin modes have a true disc. setting). The Relic mode (dual tone mode) is next deepest, and is preferred by some
because of its two tone ID. The coin mode sees targets a hair less deep than the other two modes in air tests, but it is also
the most stable mode.

It is not always necessary to hunt in what would seem to be the "right" mode for that application. Some folks like to
prospect in the Relic mode where there is lots of trash with the nuggets. I've heard of folks who beach hunt in prospect
mode to get a slight increase in depth. The best choice depends on the application and your personal preference. Here's
my opinion on some possibilities in different applications: I think the coin / jewelry mode is best in areas like open fields
without large amounts of trash. The relic mode is best for high trash areas, like old parks or ghost towns, it works well
there with the alternate mode, trigger forward to disc out the iron trash. Prospect mode is best for nugget shooting .
Prospecting is the most sensitive mode (though only slightly) and as noted, is best where there is not too much iron
junk or other trash, because it lacks a discrimination mode.

20) What should the gain setting be when detecting for gold?

One of the main keys to detecting small gold with the MXT is cranking up the gain to the +3 MAX. Having the 6 inch DD
is also very worthwhile, both from the stand point that with its small size it is more sensitive to small gold, but also
because it allows higher gain settings than the 950 coil under mineralized conditions. It is also less susceptible to
changes in soil mineralization than the 950 standard coil. In doing some tests in my yard, I found I could barely detect
a 0.5 grain flake with the 950 coil at a gain of +1 (with the flake right on the surface about 1/2 inch below the coil)
- the signal was there but was so weak that in the field, honestly I probably would have ignored it, or not been able to
distinguish it from hot rock / background noise. A gain setting of +3 gave a much better response. The 6 inch DD gave a
better response to the 0.5 grain nugget at all gain settings. At times, high and variable mineralization may make it necessary
to reduce the gain, but when that happens, sensitivity to small gold will be reduced.

21) What does the iron probability reading in prospecting mode really mean?

When using the prospecting mode, probably anything that does not make the "grunt" sound (80% iron probability) should
be dug. The target ID on the MXT is excellent, however it is not perfect. The ID does not work as deep as the detector
will detect. In high iron soil areas, it is possible for small nuggets near the edge of the detection limit to score as high as
70% iron probability. In my experience, most junk iron gives a reliable signal with the special "grunt" sound. However,
if you are looking for meteorites, the "grunt" noise may indicate a meteor. Use of a magnet to collect surface iron is also
helpful. On the other hand, many small nuggets below about 2 grains weight do not give any ID indication. Tiny bits of
iron or lead can also fail to give a VDI or probability response. Repeatable targets which do not give any ID should be
investigated. If passing a magnet over the surface does not cause the target to go away by picking up any iron or small
hot rocks, the target needs to be dug. The ID will not detect to the deepest and smallest of targets. The key is that if the
target is repeatable, the magnet does not remove it, and it does not seem to move around as the coil is passed over it, it
probably is not iron (it is most likely lead or gold).

The iron ID in the prospecting mode should probably be interpreted as follows:
10 to 30% iron probability - The MXT is reasonably sure the target is not iron, dig these for sure.
40 to 60% iron probability - The MXT just can't tell - you will need to dig these targets or you will loose gold.
70% iron probability - In low mineral areas, you may not need to dig these, in a high mineral area, dig -
use a test nugget to see.
80 to 90% iron probability - The MXT is reasonably sure the target is iron and probably can be ignored.

When you are testing a target, be sure the coil is centered right over it. You may get inaccurate iron probability readings i
f the coil is not properly centered. This could cause you to loose nuggets.

The use of a test nugget to see how the MXT responds in a particular area is highly desirable. Bury a test nugget of about 2
grains size about an inch deep at the site you are testing, and see what the response is. In order to be sure you do not loose
the nugget, most people will glue the test nugget to some small plastic piece like a plastic poker chip. Some detector owners
have a full set of test nuggets of various sizes that they use for this purpose.

22) What does the VDI reading in prospecting mode really mean?

The VDI reading is a separate reading from the iron probability output. It is also different from the audio output.
The nugget shooter working with the MXT needs to learn to use all 3 pieces of information.

Many small nuggets give no VDI reading at all - their signal response is so small, the MXT cannot do the analysis
needed to calculate a VDI reading. The manual says that small gold nuggets may give a VDI from -20 to +40.
Large nuggets may give VDI readings from 40 to 80. Items above 80 on the VDI scale are unlikely to be gold,
but still may be well worth digging (hey, even prospectors drop coins once in a while).

23) What is the best coil sweep speed for coins and what is the right speed when hunting gold?

The MXT is not as sensitive as many other detectors to the coil sweep speed - which is very beneficial to new users
as this is a critical item for many other detectors, but is simply not much of a big deal for the MXT (with one exception
- gold nuggets). Because of its quick target response, it works just fine for coin shooting or relic hunting at a wide variety
of coil movement speeds. As a result, many folks learn to work their MXT quickly through parks and schools, as it tends to
increase their finds. However, this does not hold true when prospecting for gold - this is a case where one needs to go slow
or nuggets will be missed - especially the smaller ones. Slowing down a bit can also help find the deepest coins near the
limit of the detectors ability.

24) Can the VCO pinpoint mode be used to pinpoint gold nuggets?

The VCO pinpoint available by pulling the trigger in coin shooting or relic modes can be used to pinpoint if the gold nugget
is large enough. It doesn’t have to be huge, but nuggets below about 1.5 to 2 grains don't respond well to the VCO pinpoint.
Excessive iron in the ground can also cause problems, but it sometimes it is possible to pick out a target even through this
type of condition. It is far easier to pinpoint in VCO mode than the regular prospecting mode, and it is easy to flip from one
mode to the other and back again, so its worth giving it a try.

25) Can the Relic mode be used to hunt gold nuggets?

Some folks do prospect with the MXT in relic mode as the two tone system is easy to use. You do lose a slight amount of
depth, and/or slight sensitivity to small nuggets, but the loss seems to me pretty slight. Getting an ID for iron is fairly
reliable in relic mode, but the VDI does not tell any difference between lead or gold - in spite of what the possible target ID
might be saying. You can get gold nuggets with the same VDI numbers as you might for lead shot, bullet casings or bullets.
The smallest and deepest gold will not produce any VDI score at all (as the max detectable depth is slightly deeper than the
depth the ID system will work). It is my opinion that relic mode might be better for prospecting when you are in an area with
a very high amount of iron trash, where the ability to actually discriminate out iron would be needed. When using
discrimination while prospecting always be sure to set the amount of discrimination very low, or small nuggets can be
accidentally eliminated.

One of the things you can do to try to get the best of all worlds is to switch modes. One can hunt in prospect, then when an
interesting target is found, switch modes and see what the other modes say about the target before digging. The
coin/jewelry and Relic modes also offer VCO pinpointing which is handy if your nugget is large enough to respond to the VCO
mode.

26) What about rechargeable batteries?

Although Whites offers a self-contained rechargeable battery system for the MXT, I have been using NiMH batteries since
I got my MXT and they work just fine. I get about 20 hours of operation per charge. If you only use your detector once in
a while, it is probably not worth it to buy the rechargeables, but if you use it at least 5 or 6 hours per week on average, its
worth it to get them. If you use your detector often enough, the rechargeables will save you a fair amount of money.

27) I was running my MXT and the screen suddenly went completely blank. What should I do?

A small percentage of MXTs seem to have this problem once in a while. I had this problem intermittently with my MXT,
however, after doing it about 25 times over a month or so, it stopped. I never sent it in, and I have not had it happen even
once in the months since, though I have used it regularly. It appears to be a contact/connection problem which can be cured
by re-seating some of the ICs. If it gets bad enough to be worth sending in, it can be easily fixed by Whites. Otherwise, if it
only happens once in a great while, just turn it off and turn it on again - re-booting the computer system cures the problem.

+++++++++++++++++

I hope you have found this MXT FAQ of some use.
 
Thanks for the post Rudy.
I gotta admit I'm one of those people that can't seem to read directions til after I've done it wrong a dozen times or more. I misplaced the manual shortly after getting mine, so I spent most of my time just putting it on the factory settings and going.
One of my biggest faults is not learning the vdi numbers, if I see, dime , quarter or whatever and a solid bar, I'm already digging and forget to note the vdi number.
Ohiodigger kinda jarred a few brain cells loose by mentioning the vdi for nickles, so hopefully I can start paying attention to more stuff.
But overall, its a great machine even for a lucky but unskilled person like me
Happy hunting
 
I like the use of using the question technique here.

I think it helps folks connect better in their thinking and understanding.

Thanks for sharing Rudy.
 
Thanks guys. I've had this on my computer for years now and thought it would be good to post it here.
 
I also want to add...In my personal findings is I like to run mine in relic mode, gain at plus 1 and disc at 2, this thing will go DEEP!! like I can nail a wheatie easy at 10-12 inches!!!
 
MXT VDI numbers

Helpfull info that should be included in hand book
 

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One thing nobody mentions about these MXT All Pros, is their ability to pull coins to the surface. ( who needs depth). Found a wheat, a silver dime, and a nickle tonight all on the surface, also a BF silver half earlier this spring, and a V nickle last fall, Not to mention all the clad halves quarters etc it keeps pulling to the surface !!!

:hornetsnest:
 
Couple observations and questions.
1.* I hunt an area that is ripe with pull tabs. all kinds and shapes and ages, and in all conditions. In this area, I notch out anything below 50 vdi except a solid 20, which is almost always a nickel.above 50 could be anything.
It just isn't worth it to me to dig 10,000 pull tabs in this area. in homestead hunting I don't do this tho as the probability of them being a pull tab are very small.

2. In my one good area that I have hunted over and over, I have noticed that when the ground has good moisture in it, bottle caps are harder to tell from pennies. Altho Rudy's post about how to tell, works most of the time, there are times you are just sure you have a coin only to find a bottle cap.
Now that the ground is bone dry, the majority of the bottle caps will have a brief zinc signal in them and are much easier to tell, but now some of the wheat pennies sound like the bottlecaps in moist ground , giving that occasional scratchy sound and having a smaller bar show up on occasion.

3. my questions are, what causes this ? and Having just found out how to tell what my soil mineralization is with my machine, ( I am a slow learner) i come up with a number of about 50 in the ground I've checked so far. what does this tell me with this machine?

Thanks
 
Couple observations and questions.
1.* I hunt an area that is ripe with pull tabs. all kinds and shapes and ages, and in all conditions. In this area, I notch out anything below 50 vdi except a solid 20, which is almost always a nickel.above 50 could be anything.
It just isn't worth it to me to dig 10,000 pull tabs in this area. in homestead hunting I don't do this tho as the probability of them being a pull tab are very small.

2. In my one good area that I have hunted over and over, I have noticed that when the ground has good moisture in it, bottle caps are harder to tell from pennies. Altho Rudy's post about how to tell, works most of the time, there are times you are just sure you have a coin only to find a bottle cap.
Now that the ground is bone dry, the majority of the bottle caps will have a brief zinc signal in them and are much easier to tell, but now some of the wheat pennies sound like the bottlecaps in moist ground , giving that occasional scratchy sound and having a smaller bar show up on occasion.

3. my questions are, what causes this ? and Having just found out how to tell what my soil mineralization is with my machine, ( I am a slow learner) i come up with a number of about 50 in the ground I've checked so far. what does this tell me with this machine?

Thanks

One of the big problems with bottlecaps is that over the years, they are made with many different alloys. Some have iron in them, some do not. The ones with iron are easy to distinguish. The ones without iron - not so much unless they are pointed crown up and you get a jumpier signal than you would if it was lying smooth side up.

As for your soil moisture question - as the moisture level in soil goes up, so too does the conductivity of the soil. If you are locking ground tracking, your machine isn't going to catch patches of soil that have more moisture than other areas of the ground you are hunting (Some areas of land will have better drainage then others. Some areas less). When you move from a section of dirt that has say, a VDI of -88 into a section that has higher moisture content, it could be -65. This will have the effect of displaying a higher VDI that what the target would be when you were in the ground you locked your tracking to. So, that bottlecap that would have rung up as a solid 50 is now going to ring up at like 62+. I experienced this phenomenon once before when I was digging up clad dimes that were ringing up in the 90's. It was the day after some seriously heavy rains and one section of the park didn't drain as well as the section I started hunting in.

Now, when the ground dries up, the minerals in the ground are going to concentrate. Ground that is normally -93 or so will be at -95 with a higher mineralization level do to the lack of moisture. This will make the ground harder to hunt. -95 ground isn't a problem in of itself, it just means that the mineralization of the ground is pretty much ferrous in nature. It doesn't tell you however how strong that mineralization is. Think of it like a cubic yard of dirt with a pound of iron filings in it compared to a cubic yard of of dirt with three pounds of iron filings in it. The mineralization of the second scenarious is much greater than the first. Much like the scenario with the moist ground, the same happens with dry ground. Those areas with the really good drainage are going to be the first to go bone dry in the summer months. The sections that do not drain as much will take much longer to reach that bone dry state to the elevated water levels in the dirt compared to the good drainage areas. If you lock ground balance in either these areas, will you get wild differing VDIs for the same type of target when you cross from one type of soil to the other.

Pull tabs (particularly the rectangular ones) are easier to discern than people think. Their geometry is not uniformally symmetrical and you will get different VDI readings for them depending upon the direction you are sweeping in (long v. short). Coins are uniformly symmetrical (no so much on edge, but, that is another issue entirely) and will give you the same VDI regardless of the direction you sweep (+/- 1 or 2). Where are the pull tabs will jump from like 19, to 25, to 27, to 17, etc.

Note on notching:

Be careful now tight you notch. Of you disc up to 50, but notch out 20 so you can find nickels, you are still going to miss nickles because they can ring up as 19, 18, or even 21. When I notch things out, usually notch out wider. For this case of 20, I would notch out 16-24 for entirely technical reasons that have to do with the real world behavior of electronic filters.
 
Thanks BCK for all the info.
Since The MXT doesn't actually have notch capability, ( that I know of, ) I only notch the 20 back in visually. I've dug quite a few 18 and 22 but so far nothing. but I haven't tested it with a buffalo or a V nickel or deep nickels yet.
 
Thanks BCK for all the info.
Since The MXT doesn't actually have notch capability, ( that I know of, ) I only notch the 20 back in visually. I've dug quite a few 18 and 22 but so far nothing. but I haven't tested it with a buffalo or a V nickel or deep nickels yet.

It really depends upon the corrosion level of the nickel and the kind of corrosion. There are some places where the nickles come out red. There are some where they come out green. And there are some places where they come out black. In each case, they have a different VDI that what is expected - so my experience tells me.
 
Thanks BCK for all the info.
Since The MXT doesn't actually have notch capability, ( that I know of, ) I only notch the 20 back in visually. I've dug quite a few 18 and 22 but so far nothing. but I haven't tested it with a buffalo or a V nickel or deep nickels yet.

Actually, the MXT does have a notch capability. If you run in C&J with the trigger forward, the MXT notches out the pulltabs that are in the VDI range immediately above the nickel (it won't notch out the pulltabs that are below the nickel range). Grantes, this is not a general purpose notch, but it has one nevertheless.
 
Actually, the MXT does have a notch capability. If you run in C&J with the trigger forward, the MXT notches out the pulltabs that are in the VDI range immediately above the nickel (it won't notch out the pulltabs that are below the nickel range). Grantes, this is not a general purpose notch, but it has one nevertheless.

Thanks Rudy. never knew that. I'll give it a try in a couple badly infested spots and see how it works for me.
 
Actually, the MXT does have a notch capability. If you run in C&J with the trigger forward, the MXT notches out the pulltabs that are in the VDI range immediately above the nickel (it won't notch out the pulltabs that are below the nickel range). Grantes, this is not a general purpose notch, but it has one nevertheless.

Tried it this morning, but when I push the trigger forward, it just locks in pinpoint mode. What am I doing wrong ( I have the all pro if that is different)
 
Tried it this morning, but when I push the trigger forward, it just locks in pinpoint mode. What am I doing wrong ( I have the all pro if that is different)

That could be it. I was speaking about the classical, original, MXT.
 
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