Question for Tom (10.5'' coil construction vs 8'' and 12.5'' coil)

Hi Tom,

I looked but i couldn't find an answer to this 2 part question.

Part I.

I was wondering why the design of the CZ 10.5'' coil is so different from the 8'' coil and the other concentric coils like the Sunray 12.5 inch coil. It looks like an elliptical coil inside a circle. There must be some kind of benefit in having a design like that? Is there greater depth or perhaps better target separation or improved recovery speed over the basic spider coil of the same size? (I have also read somewhere about the so called wrap around affect, does that have to to with the size of the coil or the specific design of the fisher 10.5 inch coil?)

Part II

The reason i ask is because i just acquired through a trade the FZ-12.5'' coil, i haven't tested it yet since it's still in the mail, but i was going to sell my 10.5'' coil right away. I know you mentioned that there is no difference between the two, (although i have read that some users report a tiny improvement in ground coverage and depth) so if the two coils perform the same and weigh the same, there is not reason to keep the 10.5'' coil is there? (I will be using it in wide open fields.)

Thank you very much for your help,

Yev



Edited 2 time(s). Last edit at 08/23/2009 07:12PM by Idreamin3D.

1. The transmit coil is the outter 10.5" ring. The receive coil is the 5" x 9" elliptical coil in the center. It is specifically designed to give a good compromise of the best of both worlds. 5" width for better separation,,,,, yet large enough to give better depth.
....Yes; a larger coil does have a electromagnetic wrap-around effect due to the nature of the EM footprint.
If you have time, you could read "Head-to-Head Comparison Testing" and "Coil Size Myths" found on the homepage of this web-site.

2. If you can, I would recommend you perform a definative head-to-head comparison between the 2 large coils. Also..... test a bunch of nickels (in an air-test) with the 12.5" coil.....and make sure it's ID is as accurate as the 10.5" coil.

Thanks Tom, i have read those articles before several times, but it was good to read them again, it seems like i get a little more every time i read your stuff.

I will do the head to head comparison once i get the coil, but I was wondering, how did you come to the conclusion that the two coils analyze the same amount of soil, is there a way to measure that?

Thanks,

Yev

I have access to a RF/EMF field-intensity meter w/scope.... and can volumetrically analyze.... with fairly precise accuracy.