Ground Balance Changed

[Augustinus430]

Hello all:

I began to hunt in a yard and followed the suggested procedure prior to ground balancing. I went to AM>nothing under coil>Ground Balanced>came up with 38. I ran all of this with Coiltek 6" "digger" on. I thought that I should change to a concentric, so I broke out the ML 6" concentric (trashy area). When I ground balanced again, I came u with 16, what gives? Was this supposed to happen? I contemplated going back to a "DD" coil since from what I have been reading, this highly mineralized soil would be perfect for this scenario. I'm confused, I have read Randy's book many times. Cheers.

 

[Old Longhair]

In highly mineralized ground a DD will always perform better than a concentric. It has to do with the total volume of the detection field. A DD is looking at a much narrower "slice" of ground, so it has less to compensate for.

 

[mapper65]

I agree with Old Longhair. I've also noticed that whenever I change coils at the same site I will typically get a different ground balance numbers.

When you have time put your detector in ground balance tracking and then press the ground balance button and watch how ground balance can change as you make your way through an area. For the most part you will get slightly varying readings but from time to time it can wildly swing. That could be part of the issue that you are seeing unless you ground balanced in the exact same spot as you did originally.

 

[Old Longhair]

unless you ground balanced in the exact same spot as you did originally.

I did exactly that when I tested the new Coiltek coils last fall. At one point in the test I GBd the exact spot at three locations with four different coils. At one of those locations the stock 9" 7.5kHz concentric coil GBd @ 19, the 6" 3kHz Digger GBd @ 18, the 15" LF GBd @ 22, and the 15" HF GBd @ 28. And at another site the same coils GBd @ 27, 27, 24, and 35 (respectively).

Different size, frequency, and configuration all play parts in what optimal GB will be.

And it may have been a fluke, but at one point I experienced a scenario where EMI seemed to affect GB. I was near power lines, and the only explanation that I could think of, was that stray voltage was somehow effecting the magnetic minerals.

 

[Digger]

I'd stick with the DD coil as, based on what you've said, it sounds like everything is working as I would expect it should. A DD coil will provide a lower ground phase number than a comparable sized concentric, due to the design characteristics of the coils. That is why I recommend using a DD coil whenever your ground phase number is 28 or less, while using the stock 9-inch concentric at 7.5 kHz. (first paragraph of page 51 in the eBook)
Your 6-inch concentric at 7.5 kHz should provide a similar ground phase number, compared to the 9-inch at 7.5 kHz. HH Randy