I just recieved a new minelabs xt505. I'm learning how to use it. I laid out some keys, pennys, silver and gold rings like the manual said to do to test detector. keys read on the scale 19 to 21, silver was 42 to 45, but the gold read21 to 27. is this were gold should read. I hope this is not a stupid question, but i'm new. if any one has tips on setting up a xt505 please help.