Instruction manual
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My Circular Discrimination Theory
76
Earlier, I mentioned the discrimination dierences between the three
models of X-TERRAs. As I pointed out, the TID numbers on the X-TERRA
30 & 305 range from a low of -4 to a high of +44, the X-TERRA 50’s TID
values range from -9 to +45, the 505’s TID values range from -9 to +48 and
the X-TERRA 70 and 705 range from -8 to +48. Although I was glad to see
the discrimination expanded on the 505 (compared to the X-TERRA 50), I
believe these notch segment numbers may be more than simply numbers
assigned to the “high end” and “low end” of the available Discrimination
Scale. When scanning a coil over a small piece of ferrite, I found the
X-TERRA 50 will lock onto a -9 TID reading.
When I passed that same piece of ferrite under the same coil connected to
the 505, 70 or 705, none of them will lock onto a stable reading. Instead,
the TID of the ferrite target would bounce between -9 and +48 on the 505.
And bounce between -8 and +48 on the 70 and 705. Because of this, when I
am hunting an old farm site, I usually notch out the +48 segment and leave
all the other notches open on these three models.
Doing this allows me to better determine if a target is more than just a
piece of deeply buried iron. Is the -9 on the X-TERRA 50 or 505 more than
just a number? Or by adding the additional +48 “notch segment” to the
505, is it “allowed” to provide the same “bounce” on the most ferrous targets
as the X-TERRA 70 and 705?
Based on these questions, and my tests in the eld, I’ve come up with what I
call my “circular discrimination” theory.
Understanding your X-TERRA - Technology