Is there a coil for the F75 that's smaller than stock with equal or more depth?
Ronk
F-75 or most any other detector, no difference when it comes to coil performance. Some. Possibly, but it gets down to a coils geometry, the strength of the EMF field, and the size of the anticipated target you are searching for.
You will hit a point where coil size starts to loose performance on smaller-size targets like coins and rings. Start getting bigger than that point and target-depth decreases. Naturally, ground mineral make-up and the particular detector settings used will come into play.
Personally, I very seldom use a coil that is 'standard' size for quite a few years and have favored a mid-size coil to get 'practical' or 'functionality depth. Some examples:
Round 8" Concentrics on most White's offerings since about 1990. Elliptical DD's on most other brands such as a 5X8, 5X9.5 to 5X10, 6X11, and 7X10. In most applications these coils were better balanced and worked in and around most environments that the 'satndard' size coils most folks consider. And I also seemed to get a bit better and tighter VDI responses and lock-ons.
My reply is how coil selections have worked for me when searching for smaller-size targets like coins, trade tokens, jewelry, and smaller-size artifacts such as buttons, thimbles and such.
Monte