I have come to the conclusion that in some what trashy areas the 13x17 will do the job but often does not give quite as good of sounding signal as the stock coil. I arrived at this conclusion after cross checking the older deeper coins with Guvner's CTX with stock coil and same settings.
One thing the 13x17 coil excels at is covering large chunks of real estate in minimal time and still pinpoint very well.Not for extreme trash but it does very well in normal trashy public places for its rather large size.
One reason for less than perfect sounding signals may have been the iron in hole with the quarter and two of the dimes.The Mercury dime is very rust stained on both sides and the quarter and 1906d dime have rust stains on the back sides.
One thing the 13x17 coil excels at is covering large chunks of real estate in minimal time and still pinpoint very well.Not for extreme trash but it does very well in normal trashy public places for its rather large size.
One reason for less than perfect sounding signals may have been the iron in hole with the quarter and two of the dimes.The Mercury dime is very rust stained on both sides and the quarter and 1906d dime have rust stains on the back sides.