Instruction manual
Coil Applications
50
9-Inch 18.75 kHz Concentric Coil
The 9-inch Concentric at 18.75 kHz is a bit more sensitive to the ground
than the other two 9-inch Concentric coils. As such, I’ve discovered that
I have to lower my Sensitivity setting to keep it stable. As well, I nd that
it is more sensitive to lower conductive targets. That is a good thing for
small gold jewelry. But aluminum can slaw (“can slaw” is a term I use for
those shreds of aluminum cans, after being hit by a lawn mower) also falls
into that category . For the types of places I hunt, I prefer the two lower
frequencies of the 9-inch Concentric coils. With that said, if I lived near a
beach, I would be using the higher frequency coil as it is very sensitive to
gold jewelry.
5 x 10-Inch Double-D Coil
The 5 x 10-inch Double-D elliptical at 18.75 kHz is a good coil for beach
hunters and prospectors. But I don’t live near the water, don’t nugget hunt
and have moderately mineralized soil conditions. I have used the elliptical
several times in picked corn elds and it does allow me to maneuver
between the downed stalks with more ease than the Concentric coil, due
to the solid bottom of the elliptical compared to the Concentric coil’s open
web design. But I don’t nd it has the depth of the Concentric coils in my
neck of the woods, due to the Double-D design. And I don’t nd that the
depth of detection is any better than the 6-inch Double-D at 18.75 kHz.
Depending on your application, your results may vary!
10.5-Inch Double-D Coil
Both of the 10.5-inch Double-D coils are excellent choices for those who
want to cover a lot of ground and maximize their depth of detection in
highly mineralized sites. Coin hunters who are searching for those old silver
and copper coins will appreciate the stability of the 7.5 kHz version. Beach
hunters will nd the 18.75 kHz to be more sensitive to jewelry and small
targets than the 7.5 kHz version of this coil. Relic hunters should do well
with either frequency. However, I’ve visited with some relic hunters who
swear by the higher frequency coil for old buttons and lead. But again, in
my neck of the woods, with moderately mineralized soil, the depth of the
larger Double-D coils does not exceed that of the 9-inch Concentric coils.
I keep mentioning my moderately (magnetic) mineralized soil. Let me
explain how I determine whether or not I need to hook up a Double-D
coil... Keep in mind this is by no means scientic. Just something I’ve
come up with having used all the coils extensively. If I am able to properly
ground balance a 9-inch Concentric coil with a ground phase number of
28 or larger, I am condent the Concentric coil will hunt as deep or deeper,
operate with more stability, and identify targets better, than a comparable
sized Double-D coil.
Understanding your X-TERRA - Coils