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I'll try to make this as brief as possible.
My goal is to find the last of the deepest silver dimes and wheat pennies. Sure, I could have gotten a Minelab CTX3030. However, it seemed to me that if I didn't care about jewelry I didn't need a general purpose detector, just one dedicated to finding these targets in my moderate to highly mineralized soil (I'm in Oregon). According to theory (and George Payne) a detector operating at 2.7KHz and a coil of approximately 8" is optimal for a dime sized object.
Ok, so I got an X-terra 705 and a 9" 3KHz coil. (In fact a DD coil would be superior as I found out, for its separation abilities).
I made a test bed of mineralized sand (Lowes "Play Sand"). When dry it is moderately mineralized, when wet it is highly mineralized. In any case, it isn't far off from the ground around here.
Firstly, I noticed a silver dime buried to 7" depth (when this test bed is dry) read as +48 (on a -8 to +48 wheel of this detector). Not surprising. My MXT Pro with a 10"DD coil hits this target but reads $1 TID of 94. This I can buy. Even a Classic III with Mr. Bills mods hits it.
However, when the soil gets wet, even though the MXT (15KHz) still reads it as a positive hit, albeit shifted to +94, the X-terra now reads it as "-8"! It wraps around to iron! I thought this was the advantage of 3KHz, better discrimination of high conductors in mineralized soil!?
Can anyone comment on these findings?
George
My goal is to find the last of the deepest silver dimes and wheat pennies. Sure, I could have gotten a Minelab CTX3030. However, it seemed to me that if I didn't care about jewelry I didn't need a general purpose detector, just one dedicated to finding these targets in my moderate to highly mineralized soil (I'm in Oregon). According to theory (and George Payne) a detector operating at 2.7KHz and a coil of approximately 8" is optimal for a dime sized object.
Ok, so I got an X-terra 705 and a 9" 3KHz coil. (In fact a DD coil would be superior as I found out, for its separation abilities).
I made a test bed of mineralized sand (Lowes "Play Sand"). When dry it is moderately mineralized, when wet it is highly mineralized. In any case, it isn't far off from the ground around here.
Firstly, I noticed a silver dime buried to 7" depth (when this test bed is dry) read as +48 (on a -8 to +48 wheel of this detector). Not surprising. My MXT Pro with a 10"DD coil hits this target but reads $1 TID of 94. This I can buy. Even a Classic III with Mr. Bills mods hits it.
However, when the soil gets wet, even though the MXT (15KHz) still reads it as a positive hit, albeit shifted to +94, the X-terra now reads it as "-8"! It wraps around to iron! I thought this was the advantage of 3KHz, better discrimination of high conductors in mineralized soil!?
Can anyone comment on these findings?
George