I was wondering if anyone can help. I live in ma and use the stock 8.5x11 coil and hunt alot of fields. The ground balance comes in the 80s area and it seems that deeper coins dont id all that great. Merc dimes at 5the inches or so come in from the 60s to low 80s. Alot of times i get really iffy signals as well. Would a concentric coil be better or a different size dd? Thanks for any help.