:confused:CONCENTRIC 7.5KHZ or DD 7.5KHZ

[migleca]

hello everyone, I live in Portugal and wanted your help in choosing the coil 705 for my xterra, here where I live the groundbalance varies between 40 and 48, I look primarily for Roman coins and other relics, which of these coils would be best choice, concentric or DD 7.5khz
thank you

 

[7centsworth]

You will not see a whole lot of depth difference with the two. I have ground at 40 -55 and I get a little better depth in places 1 inch or so and other places I see no difference.

 

[Digger]

Although there is an inch and a half difference in diameter, I don't think you'll find much difference in depth of detection with your soil conditions. Therefore it is a matter of preference..... a concentric will provide a more accurate TID. But you don't have to overlap the swaths of a DD coil as much as you should a concentric. Therefore the DD will cover more ground with each sweep. The concentric is waterproof and the DD is water resistant. The 9-inch concentric is better balanced than the 10.5 inch DD. Another suggestion I would offer......if are looking for old copper and silver coins or bronze relics, and your soil is moderate enough to allow using a concentric, you might consider the 3 kHz concentric at 9-inches. I find it to be most responsive to higher conductive targets. JMHO HH Randy