Yep, Jason about covered it. To increase depth use Manual sens as high as it can go without falsing/chattering excessively. Rid the screen of as much unneeded DISC as you can - the sensitivity to targets decreases as you add DISC which will effectively loose depth. Use headphones. Go slow. Expect deep target signals to be pulled toward higher iron values. The penny at 12-44 near the surface will be 27-44 at 6-7" in magnetite laden soil or decayed iron-ridden soil. It is also more likely to be masked by iron flakes above it and near it, the deeper the target. Which means you have to go slow and circle around to try and get an angle that gives at least a one-way repeatable audio. The TID becomes less reliable as targets get deeper so concentrate on the audio. Which is why two-tone anything will be fine for all but the deepest targets but for the deepest you need 4-tone or Multi, which allows you to hear the variations in audio that two-tone wont. Lastly, you'll need to be patient and expect to dig deep holes that reveal iron junk instead of non-ferrous coins. The ratio of junk to good is going to rise exponentially the deeper your targets get, especially at the fringe depth. Its more work to dig deep and get nothing - so be patient. The oldest coins are more likely to be deep if the soil is subject to liquefaction (rain water filtering) or years of overburden padding that buries them out of reach of other detectors. Lastly, it is likely that you are going to have to remove the nearer surface falsing iron junk in a gridded area first before anything deep will reveal itself. The shallower targets are going to overpower that feint deep coin so they must be removed first. Did I mention it is a lot of work to intentionally seek out those deep targets? Even if you don't, probability has it you will occasionally dig a deep target even if you didn't intend to and it will be an old coin, happens all the time. But it takes more effort to go looking for them.
