Learning not to get fooled by "good" signals

[MickTwin]

I spent about 3 hours this afternoon on that trashy lawn that I found several silver coins. It's loaded with rusted nails, screws, and bolts.

Taking my time and digging everything that gave a promising signal, I came up with nothing but junk. Using my trusted Delta 4000 and stock 8" concentric coil, set up accepting everything that discriminate mode allows, 10 and above (I think this is just a little bit more discrimination than all-metal) and sensitivity set at 8.

I think I discovered a problem that I've been having. I was getting blips in the dime+ 80's and would excitedly dig... but kept finding rusty iron. Those of you who read my last posting http://www.findmall.com/read.php?58,1420282 will see how lucky I was that I dug the jumpy signal that I got. Today, I dug plenty of jumpy signals, but EVERY target was a rusted nail, screw or bolt.

Why did I keep hearing/seeing signals in the high 80's - 90's???

I finally discovered that - after pinpointing accurately, the target centered below the coil always grunted low tone iron sounds (and showed 10-20's on screen).

BUT if I moved the coil so that the target (rusty iron) was below the EDGE of the coil, I could get a jumpy signal from teens to 90's!!! All these "good signal" blips were actually just the detector reading the close proximity to the rusted iron.

To solve this, I'm learning that after hearing a good signal, first pinpoint the target accurately (center of the coil), and then sweep over it in discriminate again. Many times in trashy areas a great signal is bogus because the trash is fooling the 8 inch coil - It's near, BUT NOT CENTERED over the target.

If anyone else can verify or refute my findings please add a comment. Thanks, MickTwin

 

[Elton]

Mant times iron causes a wrap around effect on detectors. This wrap around causes the detector to see the target as a high range signal and not the true low iron target it really is.
You can try turning the detector coil 90 degrees. then swing over the target as you turn full 180 degrees.and many times this will give your electronics a better view of the iron and cause the low ID and grunt signal. It happens with many detectors, and to the best of the best..so don't get discouraged..A little practice and you will overcome that small issue. You are going to dig some iron..no matter what you do. Even if you run high discrmination.

 

[Big Boys Hobbies]

Sounds like your getting a handle on it. Iron is very tricky. If I cant get a repeatable original most every time its usually junk. Then it pinpoints way off.... Its junk!

 

[capt.]

Your doing the right thing Mick. For me the best way to ascertain the targets identity in the ground is to center it under the coil and then sweep it from different angles. Also use Monte's EPR (Edge Pass Rejection) technique and you will drastically reduce the Iron and rusted caps you dig. One will still fool you every now and then but it beats digging all of them. Sounds like you are getting the hang of that Delta!

capt.

 

[NE Digger]

its VERY important the find the exact center of the target....and then do a nice crisp sweep over that center to evaluate the target. This will provide MUCH better I'ds . Also............checking the footprint is very telling. Coin size objects will have a much smaller footprint than most iron will. Iron ramps up different too when pinpointing. good post..................