True or false Bigger coils have trouble with surface coins?

[Foilman]

When I first started detecting I read a book that said that people claimed that bigger coils miss coins near the surface. Well at first I thought hogwash but recently I found out something disturbing and maybe a useful tip. I found that my machine is much better in the all metal mode because I can hear the near misses on my swing, I then switch to a low level discrimination. Which I thought was working pretty good. However recently I have found that a strong signal in all metal and no response in the low level discriminate is sometimes quarters near the surface. Any guesses if this is normal. I think that it maybe isn't hogwash now.

 

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[Spitfire Reddie]

hmmmm....very interesting !

 

[Dick from IA]

Interesting, Foilman. I just finished a post on a Minelab forum about this very thing.

With my ML X70 I find coins consistently at 4"-7" deep, but not many shallow ones. Yet with my Garrett Ace 250 I go over the same area and get the shallow ones. I'm running at normal sensitivity; wonder if that needs to be reduced some; I'll try it and see

To be Continued..........

DFIU

 

[Foilman]

DFIU,
You got me thinking.Maybe it is worse with me having my sensitivity cranked up and it is like a null overload. I think in what I read though it had to do with round coils and the horizontal spread of your send and receive coils being concentric. It is a strange phenomena, because deeper quarters aren't discriminated until a 7,8,or 9 setting. I usually have it set at 1 or 2. Anyway I think the bottom line is I don't trust the discrimination especially when it is near the top and I am beginning to tell a surface object by listening. My machine doesn't indicate depth, not that the depth circuitry is reliable either. Don't know. A surface dig is relatively painless in the sand anyway. I bet a lot of people are have this happening and don't realize it.

 

[oldestjim]

Gosh... keep on posting... very interesting.

 

[Dick from IA]

OK, here is what I learned yesterday, using the stock 9" coil on a ML XTerra 70. I had been finding 4"-7" targets, but not the shallow ones. I was using the default sensitivity setting of 16. The X70 Owners Manual suggests 9 or less for parks with trash and shallow targets. Read the Manual again?; good idea it turned out

At this setting I was able to retrieve all shallow targets as well as even a Nickel at 7", which is good in my book. So it does appear, in my novice opinion, that reducing the sensitivity did help. Does it replace a smaller coil? Probably not, but it does make a difference using reduced sens.

If the site is overly trash laden, then the small coil would still be a must. I fortunately have an Ace 250 with the 4.5" Sniper coil, so can always rely on it for really bad areas.

DFIU

 

[LadyDigger]

Hmmmm...wonder if that is why I get the finds hubby misses? He tries to use the Minelab Exp II with the 18" coil. He complains because he says he's not finding much. I can go over spots he has detected and pull up coins. At the beach, I hit two spots he detected and pulled up several coins in both holes (of course I let him know )...no more than maybe 1-2 inches down. But he found quarters and an earring deeper than that (that I missed ). I use the Garrett Ace 150....

He has not practiced much with the 18" coil...has been using the standard coil that came with it. Keep telling him...practice makes perfect

He also said, it was harder to pinpoint with the larger coil...anyone have that prob or does that come with practice?

HH.........Ann

 

[jeff of pa]

False with the 15" Coiltec W.O.T. Coils on the Sovereign.

Don't know on anything else.

Only Detector I use a Large Coil on.

 

[Foilman]

Ron and Ann,

My stock coil was 8 inches. I have on it the 10.5 inch and find it much harder to pinpoint with the 10.5. One tip though. If you elevate the coil in the air , sometimes it helps when you do your x'ing to visually sight where you should dig but I find myself digging way more to find the target than the 8". part of that though is you are making more hits deeper.

 

[LadyDigger]

Ron and Ann,

My stock coil was 8 inches. I have on it the 10.5 inch and find it much harder to pinpoint with the 10.5. One tip though. If you elevate the coil in the air , sometimes it helps when you do your x'ing to visually sight where you should dig but I find myself digging way more to find the target than the 8". part of that though is you are making more hits deeper.

Foilman...thank you, will pass that on to him. That is what hubby says....when trying to pinpoint the location or doing the x'ing....he still seems to dig outside the actual target area. It can be so fustrating at times!!!

 

[Monty]

I think it depends on the brand of detector you are using or maybe it's just your particular coil. As far as I can tell none of my larger coils are missing shallow targets but of course if I was missing them I wouldn't know it! I know for sure I am picking up at least some shallow coins, so it must be working on them all right. Maybe that explains why I have gone behind some of the higher end detectors with my ACE 250 in a planted hunt and picked up coins that they went right over? At any rate I have over size coils for all my detectors listed below. I do find that they are a little harder to pinpoint than the standard coils and a little more tiring to use due to their added weight. Under water I use the heel of my Sea Hunter MK II to pinpoint and find it much easier to scoop that way. Monty

 

[Foilman]

DFIU,
Went out this morning. Amongst my finds were 5 surface quarters. 3 of them did not respond in low discriminate. Now I am wondering how many dollars in quarters I have left using this coil. I wanted to fiddle with the controls, but decided this time to just dig and go instead of wasting time. At least I am aware of it. I really don't want to turn down my sensitivity anyway. For now I will just dig all of the strong signals til I know what is going on and find the best way to cope with this.

 

[Foilman]

Update:
I think I found the problem. Operator error. Under Tesoro's web site tech tips there is a section about ground balance. It seems that I just so happen to be in a low mineralization area here in the northeast and usually my ground balance has little or no effect and I got so I hardly touch it. It says lo and behold that if it is turned to much clockwise it starts to reject non-ferrous items such as dimes, quarters, and dollars. Maybe it is harsh to say it is operator error because I don't think it says anything in the manual about this. If it is turned to much the left it could chirp. Well I know it was turned almost all the way clockwise. I am pretty sure this is the problem not the coil!

 

[Dick from IA]

Foilman: Glad you mentioned ground balancing; that was the other thing I did was GB it. Had been using the factory preset (27). 31 was the new setting; I'll bet that had a lot to do with missing shallower coins.

Now I'll increase sens. a bit and see what happens.

DFIU