Adjustable coils?

[DetectorMoe]

I been thinking and I thought why havent any Metal detector company came out with a two in one coil. A 11" coil that can turn in to a 9" or 6" coil.. Could that possible?

 

[Carl-NC]

It was done in the 70's by Garrett on their BFOs. BFOs use a simple mono coil so a 2-in-1 is pretty easy. Not so with VLF, where the coils have to be carefully balanced.

 

[DetectorMoe]

It was done in the 70's by Garrett on their BFOs. BFOs use a simple mono coil so a 2-in-1 is pretty easy. Not so with VLF, where the coils have to be carefully balanced.

Wow in the 70s...
I think it can be done better in todays technology.