Metal detectors are like cars,
they have many
different technologies,features, and
performance
characteristics for their intended use.
There
arefive basic types of metal detectors:
- General Purpose-Coin/Relic/Treasure
- Gold Prospecting
- Underwater & Salt
Beach
- Cache Hunting/Deep Searching
- Industrial & Security
Some metal detectors are designed specifically
for one
type of searching. Forexample, gold
prospecting detectors
are designed to be
extremely sensitive tosmall pieces of
gold.
General Purpose models are typically not designed
todetect metals as small as a grain of rice,
however,
offer far superior trashmetal rejection
compared to
prospecting models.
When
purchasing a metal detector, it is important
to consider
what type ofmetal detecting you will
do most often, and
prioritize according to
yourtypical usage.
2. How deep do metal detectors
detect
metals? [Top of page]
The most frequently asked question and
unfortunately the
most difficult toanswer! Most
general purpose models are
factory equipped to
search for coin &jewelry sized
metals at
depths of 8 to 12+ inches depending on metal
size
andalloy. To significantly and consistently
detect beyond 12 inches requireslarger accessory
search coils,
and/or to give up attempts to eliminate
trash metals.The
15" search coil responding to all metal
alloys can detect larger
metal items(coin jars)
at depths upto four feet. However,
sensitivity
to single coinsis greater with smaller
search coils.
White's TM 808 can detect 55 gallon drums at16
feet, car-sized metals at 20 feet. However, it is
not
likely to respond toindividual coins or
pieces of
jewelry.
Detection depth
varies with many factors:
- The size, shape, exact metal alloy, and
orientation
of the object in theground. Objects
of a greater
surface are detected at greater
depths. Forexample a
coin lying flat exposes a
greater surface area than a
coin layingon its
side and will be detected at a
greater
depth.
- The size of the search coil. Search coils
come in a wide range of sizesand shapes- 4",
6", 8",
9.5", and 15". There are also
differences in
theconfiguration of the coils
inside the search coil producing
different shape
searchpatterns. The larger the search coil,
the deeper
it can detect larger metal items.However, it
is
more difficult to use in trashy areas with less
depth to smallmetal items. Smaller search coils
provide better
separation in high trash and
bettersensitivity to small
metals.
- Soil conditions and the amount of minerals
in the
soil. The higher thesoil mineralization,
i.e. the
presence of magnetic and/or
conductiveproperties, the
more difficult it is
for a metal detector to cancel
theinterference
these soils produce. Detection depth is
reduced
in severegrounds. Depth may increase or
decrease with subtle changes in the
soilconditions,
more noticeably with the entry
level models. Soil
mineralizationvaries widely
around the country &
around the world.
- The experience and skill of the operator.
There's
no substitute forexperience. Knowing
how to operate
your detector and understanding
thesignals will
significantly increase
depth.
- The metal detector
used and the selection
of settings, particularly
AllMetal or
Discrimination.
3.
What types of things will a metal detector
help me
find? [Top of
page]
All metallic objects. Example: gold, silver,
iron,
nickel, copper, brass,aluminum, tin, lead,
bronze. Metal
detectors will not detect nonmetal
itemssuch as
gemstones, diamonds, pearls, bone,
paper, or stone
figures.
4.
What is discrimination? [Top of
page]
Discrimination is the ability of a
metal detector
to tell the differencebetween different
types or
alloys of metals. This allows you to
selectivelydig up only those types of metals
likely to be
of interest to them. There areaudio
(speaker/headphone)
types of discriminators and
visual (meter, LCD)types.
Most higher end models
have both types. The idea is to
increase theodds
in favor of digging valuables, and
decrease the
odds of digging trash.
5. Can a detector be set only to
respond to
gold? [Top of page]
No. There are too many variables with exact
alloys and
sizes to pin it downtightly enough to
dig only one type
of metal. For example, a large
piece ofgold may read high
on a display or audio
discrimination scale and a
smallpiece of gold may
read low on that same scale. Gold
with some
copper, silver,or platinum within its natural
alloy will indicate differently. And othermetals
with
similar electrical characteristics may read
identically.
Lead andaluminum are the most
difficult common trash
metals to eliminate. Even
withthe most sophisticated
detectors available,
expect to dig some trash. But agood
discriminator
increases the odds in your favor.
6. What is operating
frequency? [Top of page]
Frequency in a metal detector is referred to in
kHz.
(kilo hertz). It is thenumber of times the
signal is
transmitted and received by the
detector everysecond. For
example a metal
detector operating at 6 kHz will
transmit
andreceived 6,000 times per second, and at 50
kHz
50,000 times per second.
As a rule, lower frequency detectors offer better
sensitivity to copper andsilver and better
overall
detection depth and trash rejection. Most
generalpurpose
models operate at lower
frequencies.
Higher frequency detectors are more sensitive to
small metals and naturalgold. However, they have
difficulties with discrimination against
nonferrous(not-of-iron) metals. Their sensitivity
to
small metals makes them tedious touse around
trashy
areas. Most gold prospecting detectors
operate at
higherfrequencies.
7. Are there any good places left to
hunt? [Top of page]
Nobody gets it all. Just because
an area has been
hunted before doesn't meana person with
patience
and a modern detector can't still find the
"goodstuff" just about anywhere. Spending time
with
research can still turn upplaces which may
never have
been searched. Seasonal changes such
as storms,frost
heaves, and erosion, can also
renew areas, particularly
beaches.
8.
What is the difference between "two filter"
Classics and
the higher end"four filter"
models? [Top of page]
Two filter (Classic Series) and
four filter (Pro,
Quantum, & XLT) are termsused to
describe the
amount of electronic circuitry a metal
detector
uses todeal with both discrimination and ground
mineral elimination. A two filtermodel will work
great in
low to medium ground minerals and offer
fasterresponse
between close together targets in
trashy areas. Two
filter modelsare user friendly,
lightweight, and less
expensive. Four filter
modelstypically detect deeper in
mineralized
ground, have superior audiodiscrimination
and
depth, and offer more advanced features.
9. What will target ID displays or
meters do for
me? [Top of page]
Many models have displays that indicate the
likely
identification of themetal detected. This
is in addition
to the audio discriminator. Once
an audiosignal of
interest is heard the display
will give a second,
independent,opinion about
whether the target is a good
target, or trash.
You dig lesstrash with an ID
display.
ID displays are a
very accurate measure of a
targets "electrical
phase".Unfortunately, many
different metals have the same
electrical phase.
TheTarget ID will increase your odds of
digging
good alloys and decrease yourodds of digging
trash alloys. If, in a given area, a particular
indicationconsistently turns out to be trash,
such
indications in that area are likelyto
continue to be
trash and can be ignored.
10. I want to go metal detecting with friends and
family.
Will more than onedetector interfere with
each
other? [Top of page]
Yes. Like
models operating on the same frequency
will interfere
with eachother if operated within
100 feet. To search
with a partner nearby, at
leastone of the instruments
requires the
frequency shifting feature. The
Classic®
III,IDX Pro®, XLT®, QXT Pro™,
and
DFX® all have thisfeature.
11. What about all these different
sized search coils?
Do I need accessory search coils? [Top of page]
The standard equipment search coil is
ideal for
all-around searching. A person maywant to use
a
smaller search coil for extreme trash (lots of
close-togethertargets). A person may want to use
a larger
size for increased depth. Largersearch coils
15", are
recommended for larger targets (jars of
coins) at
extremedepths. Remember, with a 15"
search coil, sensitivity to
coin sized
targetsdecreases.
12. What about a carrying case for my
metal
detector? [Top of page]
For everyday use, the gun style detector bags are
recommended. The detectorand accessories can be
installed
and removed easily, without taking
thedetector apart.
Shock-proof cases are intended
for more serious storage
andtravel.
13. Do I need headphones? [Top of
page]
Headphones will increase battery life,
increase
privacy, and increase yourability to hear
signals
clearly against background noise. They are of
benefitto those even with good hearing. Crisp
sound is
typically more important thanwide
frequency
specifications. In most cases, higher
impedance
headphones(100 ohms) offer crisper
sounds.
14. What about rechargeable
batteries? [Top of page]
Rechargeable batteries will save you money if you
use
your metal detectoroften, at least once or
twice a week.
If you use your metal detector once
amonth, rechargeable
batteries will not likely
save you money.
Rechargeablebatteries do offer
the same metal detection
performance- most models
use avoltage-regulated
system.
15. Where can I use a metal detector? [Top of page]
You must have permission to search
both private
and public property from theowner or person
in
charge of managing the property. In most cases
you canlocate the owner, or available permit
system,
through City Hall or the countyseat.
If the area is city owned contact the Parks and
Recreation Department. If itis a State or Federal
Park
contact the superintendent or grounds
keeper.Known and
marked historical sites,
historical parks, and historical
monumentsare
typically off limits to all metal
detecting.
Start with your own
yard. Valuables can be found
anywhere people
havecongregated, gathered, lived,
sat, walked, played,
camped, picnicked,traveled,
or fought. Any place
inhabited before 1965, is
likely to have theolder styles
of collectable
coins.
16. How do I recover the target once I
decide to
dig it up? [Top of
page]
Care must be taken to use the
appropriate digging
tool for the terrain, andnot to leave
unsightly
excavations or holes. There are hundreds of
diggingtools designed to minimize the impact on
grass and
vegetation, and avoidingdamaging the
items found. Sand
scoops are all that is needed
in some areas.In others, a
hand gardening trowel
or spade. Challenging ground
conditionsmay
require more sophisticated tools.
Some areas may have rules on the type and size of
digging tools allowed. Makeyourself aware of
these rules;
respect the laws and restrictions in
yourarea. Unsightly
holes left unfilled are
dangerous to people and
livestock,and are
detrimental to the continued use of
detectors.
17. What kind of Warranty comes with White's
detectors? [Top of page]
White's
warranties standard models from all
defects in materials
andworkmanship for two years
transferable parts and
labor. White's two
yearparts and labor warranty often
offers more
warranty coverage than "limitedlifetime" or
extended years of coverage. One must read the
fine
printcarefully when comparing warranties.
Labor and high
wear parts are the mostlikely
areas of cost in repair
service.
18. What is sweep speed? [Top
of
page]
All modern detectors require some
movement
(sweep) of the search coil in order torespond to
metals.
If the search coil is swept too slowly, metals do not
respond, ordo not respond at as great of depths.
Every
model has an ideal search coil sweepspeed, usually
between two
and four seconds per pass.
Experimenting to findthe ideal
search coil sweep speed
allows optimum detector performance. A
first
timeuser typically has to practice to find their
comfortable search coil sweeptechnique. Seeing others
with good
search coil sweep habits is a big aid
inlearning. Practice makes
perfect. The desire is
to sweep the search coil evenly withthe
ground in smooth
even swings. Overlap each pass by at
least 50%,
alwayskeeping the search coil in motion. Recognizing
where the beep is on each pass andshortening the
passes
to zero in on the location (pinpoint)
takes somepractice
as well.
19. What about the after market devices that are
said to
add depth to mydetector, do they
work? [Top of page]
A well-designed metal detector has
all the usable
detection depth (gain)built into standard
features. The only way to significantly increase
depth
isto maximize the standard features or use
a larger search coil.
There are many aftermarket devices
that can make it
easier to hear the metal
detector, giving theimpression
of greater depth.
Their degree of success depends on
theindividuals
hearing abilities.
20. I want to go nugget shooting
once a year,
beach combing once a year, andthe rest of
the
time I want to coin and relic hunt. What model of
instrumentshould I be looking at? [Top of page]
A general purpose would give you
the best all
around performance. Only whenbeach or
prospecting
consumes the majority of your search time
would
it bewise to look at a model specifically for
that purpose. Although prospectingor beach models
offer
increased performance for their purpose,
they are notas
effective as a general purpose
models for coin and relic
hunting. | 
