AKA SOREX PRO Operating Manual page 21

Position of some metal targets on the VDI scale(for 7 kHz searchcoils).
VDI Scale
From -90 to -86
From -86 to -70
From -70 to -50
From -50 to -35
From -35 to -10
From -10 to +10
From +10 to
+30
From +30 to
+50
From +50 to
+70
From +70 to
+86
From +86 to
+90
As we see, even in the "nonferrous" VDI sectors , "trashy" targets are found with
valuable objects side by side. In other words, any valuable target may always have
nonferrous trash with similar characteristics.
Besides, do not forget that target's VDI is truthful in the reliable detection zone
only and if there is no other metal object nearby. For example, iron underlaying golden
chervonets of Nicholas II may "take" its VDI from standard +37 to "plug's" +18/+22. At full
sensitivity limit in the ground it may suddenly sound like deep copper coin with VDI +85.
It is a common feature not only for your device, but for all devices of this type.
So, any "cut-off" and no-dig of the "potential trash" is a compromise between
comfort and loss of valuable catch. You never know, may be that hundredth "kind of
plug", you did not dig after 99 of dug-up ones, was a rare princedom age coin.
Warning! When using searchcoils with a low frequency of excitation current
VDI parameters will have lower levels. And vice versa, higher frequency gives higher
VDI.
AKA LLC +7(495)623-4026 621-0481 http://aka.2000.ru aka_md@mail.ru
Selective Metal Detector SOREX PRO. Operating manual.
Objects
hot rocks, incorrectly set up ground.
small nails and other metal scrap.
medium size wrought nails, small arrow heads.
large wrought nails, medieval knives, flat arrow heads, horseshoes,
locks and other fairly big iron objects.
in this "iron" sector ferrum is hardly presented, and nonferrous
objects masked by iron come across, small odd-shaped objects made
of low-conductivity nonferrous alloys (bronze crosses, thin golden
earrings, chains).
Pay special attention to arrow-like and thin loop-like hodographs in
this sector.
foil, small bronze crosses, small shotgun pellets, small pieces of gold.
pre-Peter Russian coins ("flakes"), "sailor hat" bottle caps;
1,2,10,15,20 kopeks USSR coins, minted before 1961.
Golden chervonets of Nicholas II, screw plugs; USSR 3.5 kopeks,
minted before 1961; Horde dirham.
poula, "flake" of the Copper Riot, small coins of the Russian Empire
and early USSR, billon coins of the Russian Empire and early USSR,
small silver coins of the Russian Empire of the 18th century and the
beginning of the 19th century
Large copper coins, silver rubles, as well as large flat or spherical iron
objects (helmets, kettles, plows, axes etc).
ground on the unbalanced device, hot rocks, as well as very deep
large objects made of high conductivity metals (for instance,
aluminum bowl, big silver salver).
Hot rock is notable for stretched "rubber" signal, while signal from a
metal object is usually concentrated in a small point.
21