A poster on the etrac forum solved my problem ..I was getting a null when I passed over a piece of surface trash then a buried coin 8 inches away...My sensitivity setting was too low (auto) so I increased it to where it was little bit unstable (23) and it picked up the dime 3 inches away with the 11 inch stock coil.. I maxed it out to 30(really unstable) but I was almost able to pass the coin under the 3 inch glass test with a pulltab on top..Try increasing your sensitivity in trashy areas to get coins next to the junk