Coil use and falsing

[machineman]

I went to an old town site this weekend. I used my 705 with the 9" mf and the 10.5" hf coils. There were a lot of nails. So much so that I would get 5 or more low tones on each sweep mixed in with a lot of highs. I didn't bring my 6" mf coil so I didn't have a chance to use it. I know there are good targets down there but I didnt find anything. All the targets had iron tones mixed in so I had trouble deciding what to dig. I'm not sure I had the detector setup right being that it is new to me. The soil in the area is red iron clay, is it possible that with the sens. set at 25 the detector was falsing on the soil? I went to a river later and had similar problems. I found some coins there but only a few had no iron tones mixed in with the highs. I plan on getting the 6" HF DD coil also, between the 2 6" coils which one do you think would be best for an area like the one I was at? Thanks

 

[Old Longhair]

The soil in the area is red iron clay, is it possible that with the sens. set at 25 the detector was falsing on the soil?

Absolutely! Excessive nulling or falsing is often due to the SENS being too high for conditions. The larger coils see deeper and large concentrics look at a bigger area, so the accumulative effect of seeing all of that minerization is overwhelming with the SENS set high. A DD coil of equivalent size will always our perform a concentric in high minerals due to the narrower slice of ground that it's looking at.

I plan on getting the 6" HF DD coil also, between the 2 6" coils which one do you think would be best for an area like the one I was at? Thanks

Hard to say for sure. You can see what each ground balances at (higher numbers are better), or you can use your stock MF coil to measure ground minerization per BarnacleBill's procedure to determine just how "hot" your ground is.
Given what you've said about the conditions and what you're looking for, I'd stick with the 6" MF if possible. It will hit on coins harder, and it will give the most honest TID. In iron rich soil with lots of iron debris, an HF coil which is more sensitive to smaller targets, and that sees low conductors (like iron, lead, and gold) better might not be the best option. But if the ground is "scorching" hot, a small DD might be the only thing that will work.

[size=large]Procedure in Normal GB mode with GB Tracking "OFF" and Sens=20:

A. Auto-noise cancel in the area you will hunting with the coil held 3 feet above the ground and parallel to it.

B. Locate a target free area of soil.

C. Engage Normal GB & remain in the GB screen.

D. Place coil on the soil. Do not press the coil against the ground! This will distort the coil shape and give an inaccurate result. Simply allow the weight of the machine to lightly keep it against the ground.

E. Press the Auto GB button and raise coil about two feet above the ground before Auto GB has completed. If by the time you reach the apex of pulling the coil up to two feet it doesn't complete, then pump up and down from just above the ground to two feet high as accurately as possible. Recall that Auto GB signals with a tone when completed.

F. While still in GB mode press and hold Patterns button to get the numbers. The numbers are six digits in length but read out in three groups of two that will repeat if the Patterns button is held down. Therefore 99 99 99(almost a million) is the largest number possible and 0(00 00 00) is the smallest. Forty-six thousand would appear as the following sequence, 04--60--00. Make a note of the numbers which we will call the "IRON NUMBER"(Magnetite...Black-Sand).

G. As a reference, numbers in the thousands are mild ground, medium grounds tens of thousands , and hot hundreds of thousands. For clarity:

1. 0(zero) >> 10K mild ground.
2. 10K >> 100K medium ground.
3. 100K >> 1M hot to scorching.[/size]

 

[machineman]

Wow that seems like an interesting process. I will try it, thanks. I plan on getting the 6"dd any way for nugget shooting so I will be able to test them against each other. I think I had a GB of about 60 which I thought was low mineralization but the way it was falsing made me think it must be the soil. I was running about 25 sens. What do you normally run? Sad that I probably wasted those 4 hrs running around with the sens too high. When the XT falses does it usually false in low tones?

 

[Old Longhair]

I never get GB numbers anywhere near that high, and other than when I can run the LF coil, I'm using a DD of some sort. I also like running in AM, so I'm listening to Threshhold breaks too, My SENS is set as hot as I can w/o excessive nulling or falsing. You can get used to the occasional blip, but the machine should run stable to keep you from losing your mind, and/or keep you from wasting time chasing ghosts

If you experienced substantially more falsing than nulling, then I might be inclined to consider EMI as another possible problem. A dirty cell phone, an underground fence, a neighbor's Wi-fi, or a number of other things could have caused it.

If you experienced substantially more nulling than falsing, then I would speculate that you were possibly swinging too fast. If it happens again, try slowing down. One reason that I hunt in AM is because it teaches you just how slow you need to go to isolate good targets hidden in trash. By listening to the null and going slow, you can tell if a false is related to the edge of a larger piece of rusty trash. If after slowing down you still have excessive nulling, then you have a choice of either dialing the SENS down further, or switching to a smaller coil. The more that you listen to what the machine is telling you, and the less that you try to convince the machine that it's a good target, the more time that you will spend retrieving worthwhile finds.

One more simple thing to do, is to remove the coil cover and clean it and the coil. Small amounts of minerized dust trapped in there can raise all heck too.

 

[machineman]

Thanks, sounds like I need more time just learning the machine.