Just a question, i am not getting around very well right now so i sit on the couch and read or play with detectors. Was air testing a f75 se , 2012 production date i think. Using the 5" dd coil, sensitivity 72, discrimination 17, 4 tone , bp process. Measured a new quarter at 9" air testing moving it rapidly back and fourth. Does this seem right? Never used it outside. Thanks for any info.