I'm constantly buying, selling and trading detectors and a few days ago traded for a like new 2200. When I tried it I found it reads down scale with both the audio and meter on a dime deeper than four inches and a quarter deeper than 5 and a half inches. By downscale I mean it drops from a dime or quarter signal to a zinc penny signal. The ground here is virtually mineral free, so it isn't the problem. I've had three 3300's and although the meter would only ID correctly to 7 inches or so they held a tone to their maximum depth. My question is do all 2200's drop a tone and meter ID on deeper coins. Thanks for any replies.