Chapter 5 GMT Searching
Field Use & Tuning Tips
Overload:
The GM24k will overload when the coil is over
a large object or extremely heavy iron miner-
alization. Lowering the SENSITIVITY will
usually cure a mineralized area, but will not do
much to eliminate a real target. With a little prac-
tice you will figure it out. If the overload seems
everywhere it is probably mineralization and
lowering SENSITIVITY is essential.
Target I.D.:
The GM24k has three different target identifi
-
cation systems. First and foremost is the audio
response. In the All-Metal (or ZIP) audio mode,
the detector sounds off with a scaled pitch and
volume raise over targets. In Beep mode, the
detector will give a high tone for mostly good
targets like gold, silver, brass, and aluminum,
and a lower tone for targets more likely to be
iron junk. It also displays a Target I.D. number,
using a scale from 0-99. You might think of this
as a “dig percentage” meter, with higher num-
bers being more likely to be a good target to dig.
There is also a Target I.D. Bar, which gives you
a block in the Iron, Gold, or Alloy ranges. Seg-
ments farther on the right of the screen are more
likely to represent good targets.
Even with all of this information presented by
the GM24k, it is generally a good practice to
dig everything in gold country. Very small gold
nuggets can fool any discrimination system, es-
pecially where the gold is encased in host rock.
Still, in challenging areas like mining camps
the Target I.D. system can give you more infor-
mation about targets - it’s up to you to dig it or
leave it.
Misclassifying Iron:
The Target I.D. will consistently identify some
types of Iron and Steel objects as non-ferrous,
particularly flat thin steel such as a can lid, very
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large pieces of iron, and small solid pieces of
iron like heavy washers. Because this is a gold
detector, it was essential to design it so that it
would tend to call doubtful targets “non-ferrous”
or “possible gold”. In this way, eliminating the
possibility of mistaking gold for iron.
Ground Scan mode tips:
Prospecting takes patience - with a metal detec-
tor it requires even more. There are certain areas
where the gold is so fine that metal detecting is
not an efficient recovery technique. For these
areas you can use the GM24k’s Ground Scan
mode to track mineral deposits.
This feature is excellent for dry washes, creek
beds, and old channels where you might want
to process the dirt using a sluice, dry washer, or
even just a simple gold pan.
Hold the Padlock button on your GM24k and
the screen will show you the ground phase (two
digit number) and strength (top Target I.D. bar).
Find an area likely to contain black sand (and
therefore more likely to have gold) and sweep
the coil over the stream bed normally. Wherever
the concentration of minerals are the strongest
(Target I.D. bar fullest), drop a marker.
As you continue down your path you will end
up mapping the pay streak with your markers,
giving you a lane to work with your recovery
equipment. The sensitivity control works in this
mode as well. If there is no ground present, the
first Target I.D. segment will flash
Frequency Shift:
If you find yourself detecting with others, or
underneath power lines, you may encounter
EMI (electro-magnetic interference). Turn your
GM24k off and hold the Iron Cancel button
while powering it back on. Select a different fre-
quency, listen to see if the interference is gone,
and then power the unit off to save the setting.
Turn it back and get detecting!
Summary of Contents for GM24k
Page 32: ...QUICK START ...
