DD coil

Tom, question concerning coil size-- width versus length. Presently I am using a 6 x 10 Whites DD coil and a 2 1/2 x 9 Hot Foot coil (both DD coils)on a White's MXT. My question is how much more effect on depth, if any, does the width of the coil have? Secondly, in somewhat neutral soil (55) would a 6" concentric equal the performace of a DD? Thirdly, can a forum get any better than this? I don't think so.

Frank

Frank,

1. Primary concern/effect: With narrow coils.....increasing the 'width' of the lateral size of the coil....gives a non-linear increase in depth. Especially if the initial coil's width is extremely narrow to begin with. (((This ONLY holds true for air-tests))). There are other secondary (yet, important) factors/variables that come into play......such as: can the archetect of the electronic platform 'handle-and-process' the increased coil size (and signal strength increase) in a linear fashion......so as to 'show' the true resultant of coil width increase.
Now............if the coil config/width-size-change is to be measured using dirt......infinate variables come into play. The more 'neutral' the dirt......the better/more it'll mimic air-test results. If the dirt is heavily mineralized....increasing the width of the coil (and subsequent footprint) will then allow the detector to 'see' MUCH more mineralized dirt......and MUCH more target. To what extent???? This is where the criticallity of a test-garden in YOUR conditions ... is paramount. Mother-nature/geophysics prohibits me from giving a non-variable 'constant' ....for an answer.

2. This is mostly answered in "1." above. Plus.....I'm uncertain of the coils you refer to......as you state a 6" concentric after you refer to a 6 x 10 DD. Is this a third coil.....or are you IRT the 6 x 10 coil. If you have a 6" round/concentric coil (and are not IRT the 6x10 DD).........then my answer will bias slightly more towards the 6 x 10 DD coil for greater depth/performance........(over a 6" round coil).......as it is a larger coil; yet, 'sees' a limited amount of mineralization (even though your mineralization is somewhat low) due to DD configuration. Once again......even a simple test-garden with one clad dime buried at ...say.... 7-3/4" deep.........will instantly start to give you your answer in YOUR dirt.

3. Yes...... MUCH better. IF more time was available for all of us! (Thanks!).

Thanks for the reply, Tom. I'll try the dime test. I must say this, though, in this black gumbo soil of North Texas, no machine outside of a PI will find a coin 7 3/4" deep. Sandy or sandy loam, yes. But not here.Love the beach DVD.

Frank

Then I would venture a guess and say that your ground is more mineralized than you think....if 7.75 is the deepest you can detect.
In that case I would think a DD coil would do better than concentric. You should find out that a small DD coil has better potential
depth relative to its size than a given stock coil.

Correct. Sounds like fairly severe dirt mineralization. DD coil configuration would be the preferred choice. Once again..... I recommend a test-garden.