I put a dime in a seam in my garage floor which holds it pretty much straight up an down on edge. I was playing with the Deus and the 11 inch X35 coil in full tones. When sweeping with the coin edge parallel to the centerline of the coil, it gave a kind of double high tone. I raised the coil until I could barely get a good high tone, then started moving 90 degrees while keeping the coil centered so that the coin was perpendicular or sideways to the "knife edge" of the coil. The signal disappeared after about 45 degrees. At 90 degrees, I lowered the coil and eventually got a signal but it was iron to foil sounding.

Then I kept sweeping using the pull back method. At about 2 inches from the tip of the coil, I started giving a very good high tone. I pulled back until the tip was a couple of inches behind the coin, where the high tone quit. I pushed the coil forward. About an inch or 2 from the front tip of the coil, the signal went back to low tone, low number situation until the back of the coil got very close to the coin at which time the detector started giving a high tone again and the tone continued until a couple of inches ahead of the coin.

Result: With the coil in line with the coin, high tone in the middle of the coil and nothing at the tip. With the coin crossways, high tone at the toe and heel and iron tone in the middle.

I thought, "That's strange". I pulled out the T2 with a Sharpshooter coil. Same thing. Same with the Impact and small football coil and Omega with the 9x5.

Later, while detecting, I stuck a nickel in the sand (GB 86, mineralization almost maxed out) and found much the same thing, double nickel tone in line, good nickel tone on toe and heel and absolutely no tone in the center of the coil when the coil was cross ways to the coin. I have never read about this before. Before now, if I got a high tone and turned 90 degree and it turned to iron tone, I just moved on.

I thought, "this is where a concentric coil would be better". I put the 7 inch coil on the Impact. Now this freaked me out. It did about the same thing!

Any thoughts on why the signal disappears in the middle of the coil but reappears at the toe and heel of the coil? I noticed the same thing on small chains.

No engineer here...but isn't the shape of the emitted signal "conical" (top to bottom) and radiates from the outer edge of the coil? I suspect that may have something to do with you results?????

No clue, I've always found more 'on edge' coins with a concentric coil. One thing I do know is there are MANY times more coins masked than deep.

The reason for this is because the TX magnetic field is only vertical in the (geometric) center of the TX coil and curls outward and around everywhere else. This means a vertical coin has a peak response location that is closer to the edge of the coil. If you sweep in one direction you get a double beep. If you sweep in the other direction you get almost nothing in the middle and a normal response at the toe or heel of the coil.

It is kind of the same thing with small chains and small iron. I like to help clean tacks, screws, nails, etc. out of the kid's playground here. Pinpointing and finding them can be difficult but it is good practice. I used to chase them all over but knowing they usually only sound off at the tip has helped considerably.

Thanks again, for your replies. I don't think most people have a clue. I know I didn't.

I believe the concentric coil the emitting signal is cone shaped
on a Double D coil the emitting signal is in a blade shape from the center of the coil?

WV62 said:

We checked with both detectors and both quarter targets were gone. My brother is now a believer. LOL

Click to expand...

Me too! Before I would have dismissed it as iron on the theory that if it says coin one way and iron the other, it is probably iron.