I've done this test with my SE Pro and can honestly say the horizontal nails hide the coin.
On the following video, the E-Trac also fails the horizontal nail test.
Check it out at 1:40 of the vid:
http://www.mlotv.com/view/387/e-trac-iron-test/
Why wouldn't the E-Trac sound off on the coin between the horizontal nails in this video? Because the user was using too much iron masking. When he placed the iron on top of the coin, he still got a response from the coin. That small amount of iron placed on top of the coin was not sufficient enough to shift/bounce the coin into the masked/discriminated area (I elaborate on this "shifting/bouncing" effect in paragraph 3 below). Also, when masking is involved, you have to elaborate a little on the recover rate of an Explorer. It will take an Explorer longer to recover from a nulled threshold from masking than from a positive/non-nulled response. When nulling occurs, the machine has to come back to threshold before it can signal another positive response. I read somewhere that a return back to threshold isnot necessary between two signals that aren't masked that are swung over. Thus, there's going to be a naturally slower recover rate when a masked target is swung over first, followed by the un-masked target. I've been hearing that the E-Trac is supposed to have an faster recovery rate than the SE, meaning it's turnaround time from a null to threshold to postitive response is much quicker.
Just as IP stated, depending on the amount of iron mask you set, allows the operator to either hear or null the coin next to iron. That's why people who are using a ML default coin program will never be able to pull any good, deep targets next to iron because the good signal will bounce/drift more toward the iron/masked area, and cause nulling.
Too much masking/iron rejection/discrimination = nulled response on high conductors next to iron.
Setting your iron reject just at the threshold of your common iron items in your ground, or in other words, at the lowest discrimination/mask possible to barely null your iron = a much better chance for getting a repeatable/positive response on high conductors next to iron. While hunting in Conductive sounds, your desirable high conductive target in this case would not change its tone when it is next to iron because the "bounce", or shift of the target moves on the Ferrous axis and stays fairly level on the Conductive axis. Now that same desirable target with Ferrous Sounds set will give erratic bouncing ferrous numbers, thus changing its tone response quite a bit. This is because the bounce/pull of iron seduced signals happens mostly on the Ferrous scale and not the Conductive scale.
There's no way to null out all iron in the ground if you want to get those high conductors that are hiding next to it. Even the best Explorer hunters will dig iron, because certain pieces will false sufficiently enough to give a positive, repeatable reading. I'd rather dig an occasional tricky piece of iron than to miss a good high conductor sitting next to iron because of too much iron masking/iron rejection/discrimination.
HH,
CAPTN SE
Dan
