best inland coil for the gt

[Critterhunter]

I think the main reason why most detectors come with an 8 to 10" coil is that this is the best size for general purposes. They have decent trash seperation and decent depth. A happy medium between both worlds. That is not to say that a smaller coil isn't better at seperation in shallow trash, or that a larger coil isn't better at going deeper in cleaner ground. Ask yourself this...How many Sovereigns would Minelab sell if they all came with a 5" coil, or a 12-14" for that matter. That's why I think they have a winner in the 11" coil being sold with the Etrac. It's a machine meant for maximum depth, so they figured they'd push the size of the coil to what most people would still be willing to buy. If that thing came with any bigger of a coil from the factory it would hurt sales.

 

[kered]

"The way I understand it double D designs handle ground minerals better because of the way the TX/RX coils are positioned in relation to each other!"

exactly , having the coils side by side limits the amount of ground that is analised at any given time

 

[Critterhunter]

You may in fact be right about that....limited vision of ground so it will see less ground minerals. I've never heard that, though. I do know that a smaller concentric will often handle ground minerals better than a larger one. I've used machines that simply wouldn't ground balance right in really bad ground but going to a smaller coil corrected the problem. I'm guessing that's due to the smaller coil's ground "load" being less than a larger one, putting it into the window of balancing ability for the detector.

I've always assumed/implied from what I've read that the better ground balancing of double D's was due to the tx/rx coil orientation, not directly related to the signal shape. They are much easier to tune than a concentric, so more people opt to build them at home than the more specialized calibration tools needed for a concentric. I guess I just always assumed it was due to the somewhat picky configuration of the tx/rx/bucking coils in a concentric. The least bit of movement or signal distortion in the ground (caused by minerals) will give them problems.