I did a little experiment a couple of years ago in my test garden. I used the 9.5 imaging coil/GTI 1500, with the sensitivity set at max in zero discrimination. In my test garden I have many coins at various depths as shown
below.
<center><img src="http://members.shaw.ca/john_edmonton/test%20garden.jpg">
Now the six inch coin sometimes gave a belltone and or a quarter bouncing around occasionally. Well, I would have dug it anyways. I never turn down a signal that sometimes reads as a good target at 6 inches. 6 inches = OLD. Now, I tried the 8 inch and the 10 inch coin too. No belltone, no bouncing around for even a hint of a possible target. But.....there were a couple of constant variables. All the tones gave that low iron tone. The cursor sometimes moved around, say from iron to bottle cap. However, and here is the kicker, the depth always remained the same. It didn't matter if my coil coil crossed the target at different angles, the depth still remained the same.
Well, thinking I was on to something, I headed to a school built in the early 1900 and tried this scenario in the real world. I was at a goal post, and about 5 feet off to the outside of the metal post, I got one of those low tones, in the iron range. I tried running the coil over it from several directions, and sure enough the depth remained the same. It kept reading at 8 inches. I also want to mention, that metal detecting has been popular in Edmonton since the 70's, and this school has been hit hard. One only has to research schools at the library to find out where the old schools are. But, I dug down carefully and at about 8 inches was a nice 1918 silver quarter. Not in the greatest conditions, but it was silver, and deep. I tried the same scenario again, and sure enough, I got another low tone in the iron range, but a constant reading of about 8 inches also. Well, I dug up the target, and sure enough, a coin popped out again. This was an older Wheat Cent.
So, I normally would have past these signals up as junk because of that low tone. But, a constant depth reading of a deep signal requires further investigation. So, does a junk reading for a coin at 8 inches make a detector a poor machine? Nothing could be further from the truth.
I have always said, you are not efficient until you tell the machine what it has under the coil, not the other way around. Sure, if you like to dig coins in the top 6 inches (I do) and rely on the ID, Belltone, Imaging and Depth to get coins, you will get a good probability ratio using the Garrett 1500 for coins. But, you can push the the limits of the GTI 1500/GTI 2500 in the standard mode to get even deeper targets. But, it involves a lot of extra concentration, skills and even some deep digging....
Are you up to the task?
below.
<center><img src="http://members.shaw.ca/john_edmonton/test%20garden.jpg">
Now the six inch coin sometimes gave a belltone and or a quarter bouncing around occasionally. Well, I would have dug it anyways. I never turn down a signal that sometimes reads as a good target at 6 inches. 6 inches = OLD. Now, I tried the 8 inch and the 10 inch coin too. No belltone, no bouncing around for even a hint of a possible target. But.....there were a couple of constant variables. All the tones gave that low iron tone. The cursor sometimes moved around, say from iron to bottle cap. However, and here is the kicker, the depth always remained the same. It didn't matter if my coil coil crossed the target at different angles, the depth still remained the same.
Well, thinking I was on to something, I headed to a school built in the early 1900 and tried this scenario in the real world. I was at a goal post, and about 5 feet off to the outside of the metal post, I got one of those low tones, in the iron range. I tried running the coil over it from several directions, and sure enough the depth remained the same. It kept reading at 8 inches. I also want to mention, that metal detecting has been popular in Edmonton since the 70's, and this school has been hit hard. One only has to research schools at the library to find out where the old schools are. But, I dug down carefully and at about 8 inches was a nice 1918 silver quarter. Not in the greatest conditions, but it was silver, and deep. I tried the same scenario again, and sure enough, I got another low tone in the iron range, but a constant reading of about 8 inches also. Well, I dug up the target, and sure enough, a coin popped out again. This was an older Wheat Cent.
So, I normally would have past these signals up as junk because of that low tone. But, a constant depth reading of a deep signal requires further investigation. So, does a junk reading for a coin at 8 inches make a detector a poor machine? Nothing could be further from the truth.
I have always said, you are not efficient until you tell the machine what it has under the coil, not the other way around. Sure, if you like to dig coins in the top 6 inches (I do) and rely on the ID, Belltone, Imaging and Depth to get coins, you will get a good probability ratio using the Garrett 1500 for coins. But, you can push the the limits of the GTI 1500/GTI 2500 in the standard mode to get even deeper targets. But, it involves a lot of extra concentration, skills and even some deep digging....
Are you up to the task?