Technical information desired

[markg]

Question in relations to the F75 coils.
I would like to have an illustration of the signal pattern transmitted from both the standard 11" DD and the 5" DD coil.

From what I've read the concentric coil has a so called cone shaped pattern but what about the F75's coils?

 

[Alimo88]

it's a cone shape in one direction but the width of the coil in the other. Sort of like a wave shape before it breaks. The wave is under the common part of both loops the widest front to back and is wide as you sweep.
do an image search on "dd coil"
I THINK

 

[Alimo88]

Read this

coil info

 

[markg]

That's a fantastic illustration
Thanks

 

[tvr]

Knowing that the 11 inch coil for the F75 series is a DD coil ... what baffles me is why it still pinpoints in the center? That molded in spot near center on the 11 inch (that some people paint a bright color) is a dead on pinpoint; and not off the toe or heal of the coil.

All the DD coils I have for my other detectors pinpoint off the center of the toe and heal of the coil where the two D's intersect. That off the toe or heal pinpoint behavior is in line with expectations if the signal field kind of lines up with the diagrams at the link that Alimo88 provided.
tvr

 

[marcomo]

I've wondered the same thing about that Fisher 11" DD, TVR.

 

[Alimo88]

Maybe it is not perfectly flat on the bottom of the wave but is more like a slightly rounded wave? and it pinpoints at the little crest?

 

[tvr]

I'm wondering if it is really a modified DD winding pattern of some sort to make it peak slightly at the center. Curious, but not curious enough to cut the coil open and have a peek.
tvr