A lot has to do with marketing, and some has to do with people who state something or put it in print in a book or magazine (for those of us who remember those good old days of magazines), and naturally in brochures or other printed forms to include on the Internet. Sometimes things were incorrectly described by a manufacturer owner or other 'important person' and handed to a secretary to type out for a manual. The manuals used to, and still do, have some incorrect info because the write and the typer didn't know correct from incorrect. Today, if we have more design engineers involved in manuals and marketing we see improved information to not lead us astray.

Examples might be Minelab's nutty comments and pictures of their BBS units calling them 17 Frequency and the FBS models at 28 Frequencies, an showing all sorts of arrows pointing down from the coils. So many people believed they worked at all those frequencies, and not two, and that they generated a signal, or EMF, projected straight down from tip-to-tail. Wrong, wrong, wrong.

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jmaryt
apparently all the the info I have gleaned about this over the years is incorrect!

No, not ALL the information, but we have all been subjected to wrong information and we just need to learn and understand some of these things.

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jmaryt
results would be inconclusive in freshly disturbed soil. would be of little consequence

Depends on what 'results' you are referring to. Target response and detection depth can vary between undisturbed ground and disturbed ground if the same coin-type target is positioned at the same depth and orientation. There have been times i have found a coin deeper in both hard-packed and undisturbed ground or in loose, plowed ground than it tested after recovery doing an 'air test'. A lot of variable involved we have no control over, and plenty that we do. Detector circuitry design, search coil size and type, and using very functional settings or not having things set up right all makes a difference. Also, since you're referring to 'ground', it is important to have a good working Ground Balance when possible Remember, some makes and models are 'fixed', some are 'fixed' wrong, and some have no user control over a particular mode's GB.

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jmaryt
I have recovered coins down about 8" or so with the Mojave, but I believe I would have missed them if I did not overlap sweeps by 50%
I'm just sayin'

Certainly, any overlapping is better than no overlapping, and an a coin can be missed at that depth without a good overlap or else the detector (EMF detection field) won't 'see' t.

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jmaryt
in addendum: air tests can never be positively relied upon as the soil matrix is missing!

Sometimes, you are correct. But as UtahRich responded below, you can 'test' or learn what a nice-and-proper Electro-Magnetic Field might appear like under ideal, 'in-the-air' conditions. Ground mineralization and the influence of nearby masking trash can 'warp' the field to a degree and that can alter some results. The particular shape and orientation of a target can, as well, as it also warps or influences the 'shape' of the EMF.

In the end the side-view of the functional portion of the EMF is wider near the coil and much smaller at the farthest point from the coil, so the shape might appear 'cone' like or more of a bowl-shape, but still the strongest at a much smaller point or area the farthest from the coil.

Monte

"Your EYES ... the only 100% accurate form of Discrimination!"
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Metal Detector Evaluations and Product ReviewsI'm now 'back home' in Farr West Utah monte@ahrps.org ... or ... monte@stinkwaterwells.com 503-481-8147Detector Outfit: A selection of my chosen makes and models, with the best coils mounted for the tasks I'll take on.F-19 * F-5 * Racer * Racer 2 * V-540 * Relic * Silver Sabre µMAX * Bandido II µMAX * XLTPinpointers: Garrett AT Pro-Pointers .. Headphones: 'Hornet' .. MS-3 Z-Lynk .. ML-80 *** All working well today to make memories for tomorrow. ***