Extra Large Coil to find Arillery Shells

[mrainbolt]

I have a White's TDI-SL. I am thinking about building a 4x4 or 2x6 foot 3 wheel drag cart/coil with pvc, elevated 12 to 18 inches above the ground. Hoping to recover grape shot size and bigger.

Is basic design doable? If yes, what are the limitaions or problems with this design?

Fred

[Reg]

Fred,

To answer your questions, the answer is yes, it is doable. As for limitations, well you won't be able to operate at minimum delay. So, even if it seems to work, you want to turn the GB off and advance the delay until the signal becomes obviously stronger. Note that setting of the delay and use it or a later delay with the GB on or off.

The reason for using the GB off is with it on, there are two channels of information being processed, the main signal channel and the later channel used for GB. What can happen at a short delay is only the GB channel is late enough to be processed. If this happens, the detector will appear to work but signals will be reversed. By selecting the GB off, only the main channels is detecting. If a coil is too large and won't work at the delay, the signal may still be there but be very muted. Thus, advancing the delay until the signal suddenly becomes strong will provide the minimum delay at which that coil will work satisfactorily.

Factory coils are about 300 uh but a wide variation will work. So, you can try most anything within reason.

I would start out with a larger than normal coil and work my way up until you build the largest size you desire.

You can search this site and find info about building larger coils for the TDI. Yes, the SL is a TDI when it comes to coils.

Reg