Although I wouldn’t recommend comparing different machines using “in air” depth tests, comparing different coils on the same machine would in my opinion give a very good comparison of the depth capabilities of each coil.Looking at the above figures its pretty obvious to me the MXT performs better “in ground” than “in air”, this is based on depths of finds out in the field, for instance the MXT fitted with the 14 incher found a hammered penny on rough plough at 11″ with a good strong signal, but would only get it at 10″ in air. The figures also show what a cracking little coil the 5.3 is, matching the 10″ X 5″ DD on three of the targets even though its only about half the size of that coil. In my write up about the 14 incher I reckoned it had a 2″ to 3″ gain in depth over the 9.5 stock coil, seems the bigger the target the bigger the gain. These tests were done after the machine was ground balanced and then the tracking “locked”, the gain was set to max (+3), discrim at 1.9, in fact it was set up exactly as I use it in the field, all measurements were taken while still getting a good two way signal using headphones. |
Obviously this test is only a rough guide to compare the coils capabilities, and certainly not set in concrete,it obviously doesn’t take into account mineralised soil, or the presence of iron, if someone else tried this test they would probably come up with a different set of figures, there are so many variables when doing these tests, like the amount of interference, type of headphones used, where the cut off point for a good signal is etc etc, but it does give a reasonable idea of performance for each coil.
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Designed by Corinne Mills 2005
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