I have written this dozens of times but somehow people seem don't quite understand it, so here goes again anyway.
NEVER, NEVER, NEVER SCRUB the #$%^&%& ground with your coil!
UNLESS you are using an induction balance (IB) or old TR metal detector, And even then you have to be careful not to dislodge the coil windings. Don't do it with a BFO or a BB detector either. And if you don't know what a BB detector is - then you CERTAINLY should heed this advice.
Now why have I write this so many times? Well, it's because most people do not understand how a metal detector works, even though they may have been using them for the last 30 or 40 years.
I have posted little graphs, charts, etc, but still this goes misunderstood.
So here I go one more time;
When you operate your metal detector, internaly there is a set of parameters that allows you to operate below and above a certain null (null meaning "zero"). If you go above it you begin to operate into the positive. If you go below it you begin to operate into the negative. Anybody knows that operating this way loses depth. It's true with ALL detectors, PI's, magnetic imagers, VLF's, Multi-frequencies. magnetic spectrometers, etc, etc. If you were to be able to ground balance your detector right on the ground then you should also be able to scrub it on the ground too - and keep the same affect. WRONG! WRONG! WRONG!
The surface of the ground often has more disruptions of magnetically and linearally/randomly distributed minerals of varying types than are found even just below the surface. This is not a joke it is a fact. Many of the surface minerals come from plant life, and many of them are acids (positive) , and many are salts (negative) too, some are even neutral. If you ground balance (AKA "rough discriminate") the detector to within the first 2 inches of the soil surface (1 inch soil, plus 1 inch of grass, etc) then you have ground-balanced the detector to it's max, and I mean it's MAX. If you GB it right on top of the ground though, and use it right on top of the ground - you then have additional interference ("noise") to deal with. This will cause you to lose a lot of depth + plus the normal functions of your discrimination control (AKA "fine-tune ground balance) will suffer too, because the phase shift has been too greatly distorted. . This is not a joke either, it's how your detectors operate. When ground balanced to 1-2" above ground anything past 1" then acts as a surface blanker too, and that in turn makes your detector quit it's heavy breathing by some margin.
Additionally, the null that your detector is working hard to maintain is NEVER (perfectly) balanced to the ground surface, not even for a nano-second, but instead is ground balanced to only somewhere near it periodically, as in maybe 1/1000 of a second off and on, and besides that, the circuitry is being overdriven to begin with - by the initial surface overload configuration of mass times matrix = resistance. This means simply put, that the detector actually gets less depth dragging it on the ground surface than if you ran it 1" or 2" off the ground. The magical number is this: If you hunt in bare dirt then 1" off the ground is optimim. If you hunt in short grass, as in a well-kept lawn then the depth of search should be 1" of dirt + 1" of grass, or, 2" of search away from the ground. And if you have manual ground balance you should balance it the same too. In other words STAY AWAY FROM THE SOIL. Even with automatic ground balance the same rules apply. Remember, that ALL detectors have at least a little automatic ground balance built into the circuitry, and of not they would never stay tuned, not in a hundred light years. It's just how it is.
When you fool with Mother nature, she gets even. When you fool with physics you might lose a lot more than a decent paycheck. Having an "opinion" about this does not cut it. Having the facts puts you ahead by one horse's length in a race. DO NOT scrub any of these modern detectors on the ground, unless you just want to wear out the coil cover fast and lose depth, are a meanie enjoying being rough on your detector, or maybe just want screw up your discrimination abilities too.
You can find the same thing in Jack Gifford's (Tesoro Metal Detector's) notes, and also George Payne's detector engineering notes - about optimum search height. Here is what Charlie Garrett says too. in item #12.
http://www.brent-krueger.com/garrett2.html
'Nuff said. Now I'm going to eat some chocolate chip cookies and drink some of this Arabian coffee.
EasyMoney
![:-\](https://www.treasurenet.com/smilies/undecided.gif "Undecided :-\")
