F5, 11" DD coil and pinpointing

[djcnTexas]

I'm a new member, so please forgive this basic question.

I'm using a new F5 with an 11" DD coil and am having trouble determining exactly where the best spot on the coil is for pinpointing. I've read all about the stock concentric coil pinpoint location (with the golf ball trick) and at least 60 pages of searches for pinpointing and more than half of Mike Hillis' posts on the F5. I'm still corn-fused...just slow I guess...

I had been using an F2 with the 8" round coil and that seems simple in comparison to the new machine/coil. However, I really like the bells and whistles that the F5 has.

Thanks for any help!

 

[jim tn]

When first getting started with the 11" DD coil, it does take a little practice. On the top of the coil just in front of where the lower shaft connects to the coil there is a dot. That dot is the sweet spot and target should be right under it. HH jim tn

 

[MarkCZ]

With the 11" DD coil when pinpointing you will get a very narrow field from side to side, but from front to rear you have a MUCH longer field. That's because the detection field is a long narrow bar shape. So, you can detune it from side to side but you can't shorten heel to toe very much. But with practice you will pinpoint down to near the little round mold dot on top of the coil, but don't expect it to detune down like a cone shaped detection field from a concentric coil. But the 11" DD on my Omega I get much better target ID and even better ID at depth (the F5 and the Omega has the same platform or to say they can use the same coils).
When you move the coil across the target from heel to toe you just get better at judging the center to off target in both directions, side to side will detune better than a concentric, the problem is that heel to toe.

Mark

 

[djcnTexas]

Jim and Mark, thanks so much guys! Both answers were GREAT! Next time out maybe I won't hafta dig such wide holes. I was thinking I might need a round headed shovel instead of the sharpshooter I've been using. Now, maybe I can step down to a regular digger and maybe even smaller...

 

[Mike Hillis]

For shallow targets you can just wiggle the coil back and forth in very short sweeps (2 inches wide) over the target while pulling the coil back toward you until the signal drops off the toe of the coil. Then the target is just at the end of the tip of the coil or just back under the tip of the coil. This is easy to do and learn and will work for all DD coils. Take some time to practice and you'll be proficient at it in no time. You can even learn to do this with deep targets but it takes longer to get good at it as the field shrinks inward at depth and you have to learn how to judge this.

So for deep targets it is easier to learn to detune your pinpoint. You pinpoint the target, then while over the target you release the pinpoint button and then activate it again. (You are desensitizing the target response, in essence making the target smaller, thus requiring more exact coil placement to find it) Now you may or may not still hear the target. If you don't hear the target, press your coil more firmly to the ground and see if you can pick it up. If not, press the coil to the ground all around the original spot until you pick it up again. Once you got it back, turn ninety degrees and find it again. As has been said by Mark and Jim, that mold mark is a good reference point for center. If you loose the target completely, just release the pinpoint button, move off the target area and re-engage the pinpoint and move back over the target and try again. It doesn't take long to learn how to do this either.

On real deep targets, where the detune looses them and even pressing the coil to the ground doesn't bring in back, then just do the ninety degree check twice. Pinpoint, turn ninety degrees and pinpoint again, then turn ninety degrees one more time. Why twice? You may find that the real deep target moved, and if it moves you don't have to bother digging cause it will be elongated iron falsing off the end. Pretty easy to tell moving targets with a concentric coil but the 11" DD doesn't display them quite so clearly.

HH
Mike

 

[djcnTexas]

Thank you Mr. Mike! Like I noted above, I've read a whole bunch of your writings and am quite impressed with your knowledge, along with numerous other knowledgeable people that post on this site. I found this site doing searches about F5 reviews, etc and really like it.

I had read much about detuning and have been practicing it for several weeks. It works! However, I really appreciate the advice that you provided above. Pinpointing with this coil makes much more sense to me after you posted it all in the same place.

I live in far north Texas, close to the Red River and out in the middle of nowhere. Today and tomorrow are looking to be really nice weather to get out and pratice, practice, practice! It's supposed to be around 70 today and 80 tomorrow. I may have to break out a short sleeved shirt tomorrow! Don't mean to denigrate (or tease?) those who are still struggling with snow and frozen ground. Hang in there! When it thaws out and turns nice in the north, it'll be hot here and I'll be looking for a tall glass of ice tea HH, Dale

 

[dbax]

Listen to Mike Hill and let me add a couple of things. For awhile I thought I could retire my pinpointer the DD coil was so good at pinpointing. Mike has it right in his first paragraph and in everything else too, as well as other. I have used the technique of short sweeps back and forth as you pull the coil back toward you -- but what you need to do first is determine how deep the machine says the coin is. If it is withing the first 2", then you will indeed find the target within 1" of the tip, but if the target is below 3" you will find the target further back toward you, closer to the shaft. Example, the signal says 4", you swish back and forth, finding the center line, start pulling back and the signal get weak and you lose it, you move forward again, relocate, now dig but not right where the coil sounds but back about 2", or at least and 1" further back than you think. I am sure you have already found that when you dig a deeper target you find it almost always at the back of the hole toward you. You do not have to mess with detuning and no lose of signal. The reason for this is that as the signal along the center line of the coil moves deeper into the soil the signal profile becomes weaker or less in volume from tip to heel. It is widest at the tip or heal and begins to arch through the ground, about 1" wide !0" long and for every inch of penetration, depending on soil, the signal arch will drop back or lessen about 1/2" for every inch past 2" mark. Yes, i still use my pinpointer as some of those clads look the same color of the ground, but really, that DD coil can really spoil you.

 

[djcnTexas]

Thanks to all!

I was out perfecting my pinpointing, left the sharpshooter shovel in the shed and only carried an old Garmin digger. I got this really weird signal that kept going from iron to dime to quarter to just about the entire scale, but didn't overload the F5. I dug around a bit with the digger and at about 8 inches and still getting the same signal I decided I just had to know what was causing the varied readings. I went back to the shed, got the sharpshooter and dug down past 12 inches. Out came a very old pistola! The barrel, cylinder and hammer were a mess of rusted steel. However, the entire frame was made of brass that had been plated with chrome or silver or something and is in good condition. Looks like a 25 or 32 caliber, not a toy.

I live on about 20 acres in an area where there are a LOT of very old home places. Usually there is little left except for foundation rocks or maybe the remains of an old chimney or cellar or something. It's one of those old towns where the railroad went a different direction and the town dried up (ghost town?). Where I was hunting was only about 50 yards from the house. Now I guess I'll hafta mow down the tall, thick weeds and grasses and see what else I can find. There are 6 to 8 old places where there were houses, etc. on my land and I've still got a lot of looking to do. No coins or other valuables yet, but I'm still lookin'!