Let me start by saying this not a scientifically accurate test. I marked a dowel rod with 4, 8, 12 and 15 inch marks and buried coins(one at a time) at those depths. Coins were flat on the bottom of the hole, covered and the sand tamped firmly down to level with the top of the hole. In Pro Zero, I tested the Garrett Stock (8.5x11") coil first and then the coins were reburied at the same depths to test the NEL"BIG" Coil. The beaches here are very flat and except for the dune, which no digging is allowed, there is little dry sand. The top 2 to 4 inches is dry the rest is damp, near the dune. The deeper I dug the wetter the sand became. And, it is a saltwater beach on the Gulf Coast, Surfside Beach, Texas to be exact.
This was a test more to see if the BIG coil was stronger than the Stock coil so I tested the 8.5x11 to see how it acted and then tested the BIG to see if it did better. It DID.
I tested the 8.5x11 Stock coil first. I was able to pin point all the coins, but the deeper they were the fainter the sound.
Using a 1981 Copper Penney I first Ground Balanced on a clean spot, (the same spot for each test)reducing the sensitivity two bars, raised back to full sensitivity and tested on the surface. I got a normal strong signal with a 80/81. I the buried the coin at 4 inches and got pretty much the same, the sand being dry. At 8 inches I got a weaker but still GOOD signal with a jumpy VDI with numbers from 75 to 81.
A 2000 clad Dime. At 4 inches I got a expected strong signal with a VDI of 81/82. At 8 inches the signal was stronger/louder than the Penney, but the VDI numbers were slightly jumpy, hitting 81/82 most of the time.
A 1991 Nickel. A strong 53 at 4 inches. At 8 inches the signal was still strong, but numbers jumped from 48 to 56.
A 1988 Quarter. At 4 inches it was very loud and gave a solid 86/87 VDI numbers. At 8 inches it was a little weaker, but still strong, the VDI numbers were 85/86 jumping occasionally.
Next the NEL "BIG" Coil.
In a Nut Shell. It gave a louder signal with each coin at the same depths. The VDI numbers were still jumpy at 8 inches, but stayed closer to the normal VDI numbers. It was much easier to pin point, as the signal/sound was much louder. Louder in PP than search mode.
I did go to 12 and 15 inches with the Quarter using the BIG Coil. At 12 the signal was faint and VDI numbers very jumpy/erratic, going from 77 to 91, if I got one. At 15 inches there was an extremely faint signal when I got one, with no VDI number. I was able to adjust the Ground Balance -5 then to -10, getting a slightly stronger signal. But still no VDI.
Ground Balance for the 8.5x11 coil was 61 and for the BIG, 77.
Hope some will find this useful. I believe in deep dry sand the BIG Coil would do very well, getting much deeper and be more stabile. I intend on doing more tests under different conditions, for both if not all three of my ATP coils.
This was a test more to see if the BIG coil was stronger than the Stock coil so I tested the 8.5x11 to see how it acted and then tested the BIG to see if it did better. It DID.
I tested the 8.5x11 Stock coil first. I was able to pin point all the coins, but the deeper they were the fainter the sound.
Using a 1981 Copper Penney I first Ground Balanced on a clean spot, (the same spot for each test)reducing the sensitivity two bars, raised back to full sensitivity and tested on the surface. I got a normal strong signal with a 80/81. I the buried the coin at 4 inches and got pretty much the same, the sand being dry. At 8 inches I got a weaker but still GOOD signal with a jumpy VDI with numbers from 75 to 81.
A 2000 clad Dime. At 4 inches I got a expected strong signal with a VDI of 81/82. At 8 inches the signal was stronger/louder than the Penney, but the VDI numbers were slightly jumpy, hitting 81/82 most of the time.
A 1991 Nickel. A strong 53 at 4 inches. At 8 inches the signal was still strong, but numbers jumped from 48 to 56.
A 1988 Quarter. At 4 inches it was very loud and gave a solid 86/87 VDI numbers. At 8 inches it was a little weaker, but still strong, the VDI numbers were 85/86 jumping occasionally.
Next the NEL "BIG" Coil.
In a Nut Shell. It gave a louder signal with each coin at the same depths. The VDI numbers were still jumpy at 8 inches, but stayed closer to the normal VDI numbers. It was much easier to pin point, as the signal/sound was much louder. Louder in PP than search mode.
I did go to 12 and 15 inches with the Quarter using the BIG Coil. At 12 the signal was faint and VDI numbers very jumpy/erratic, going from 77 to 91, if I got one. At 15 inches there was an extremely faint signal when I got one, with no VDI number. I was able to adjust the Ground Balance -5 then to -10, getting a slightly stronger signal. But still no VDI.
Ground Balance for the 8.5x11 coil was 61 and for the BIG, 77.
Hope some will find this useful. I believe in deep dry sand the BIG Coil would do very well, getting much deeper and be more stabile. I intend on doing more tests under different conditions, for both if not all three of my ATP coils.