Which coil will give me the best depth?

[jraven]

I have the Concentric Standard (7.5kHz) and the Concentric Low (3kHz) coil. So far it seems there is no difference in depth between these coils.. I was wondering if the 10.5" 18.75 DD coil will give me the best depth??? Thanks for the help!

 

[Digger]

It depends on where you are hunting and what you are hunting for. Lower frequencies provide better target response on higher conductive targets such as silver or copper coins. Higher frequencies provide better target response on lower conductive targets such as gold coins and jewelry. Lower frequencies will provide better depth on larger targets. And higher frequencies will provide more sensitivity to small targets. Concentrics will go deeper in moderate soils. And DD coils will penetrate highly mineralized soil better than concentrics. Like you, I don't see much (if any) difference between the depth of any of the three 9-inch concentric coils. However they do provide different responses to varying amounts of conductivity and ferrous content. As I've stated before, the 3 kHz provides a much more distinct audio on ferrous targets such as deeply buried iron. Although I think my 18.75 is a bit "hotter" than the other two, I find I have to lower the sensitivity a couple of settings to get it stable. Kind of a wash, I suppose. In my opinion, if you are hunting in an area with higher levels of mineralization, the DD coils will provide more depth as DD coils will neutralize the effects of the mineralization. In my soil, if I am able to ground balance my X-70 or 705 with a ground phase setting higher than 28, I don't find the larger DD coil gets me more depth. It will provide better target separation. But as a rule of thumb, if I can GB with a setting of 28, I use one of the concentrics. The only exception is when I use the 6-inch DD at 18.75. I don't use it for the frequency. But in my opinion, the 6-inch DD separates targets much better than the 6-inch concentric at 7.5 kHz. And if I am using a 6-inch coil, separation is more important to me than raw depth. JMHO HH Randy

 

[pvampire]

Thank you Digger! I spent quite a bit of time last night on the net trying to figure out exactly what you just addressed as far as coils go, with no luck. You made this clear to me! thanks!