steve detector rods

Just buried 3 rosie dimes at 4", 6" and 8" so no halo effect. 10 x 5 and stock coil about the same on 4" and 6" but 10 x 5 got no signal at 8" and stock coil got just a high tone. Surprise, but should not be, TID numbers change with depth change on coins. Since I mostly relic hunt and dig all...