VLF DD nulling

[T.C.Boise]

I have a large coil project for my Whites MXT, I was first trying to make a separate recieve coil and transmit coil like a two box. I have the millihenrys and the ohms close to the stock coils. The first coils were six foot long 3/4 inch radius, I could not get them to null at all, the detector was not able to be turned up at all without an overload signal. Now I think that the DD would be better. Has anyone made a VLF DD five foot long coil ? Thank you. Tim

[Geo]

Ohh very very difficult. A 5 foot coil is needed for large objects only. So why you don't try a PI detector with a 2x2 m mono coil? No need Deep Nuling and shielding.