The Hot Spot On A Coil

[IDdesertman]

I was out last week playing around with the Makro Gold Racer alongside my GBPro. I've grown quite accustomed to the "hot spot" on the 5" x 10" DD Gold Bug coil right at the tip, maybe 1.5" back from the very tip, and with the Racer it seems the strongest signal is right dead center on the 5" x 10".

All coils have that sweet spot, but it got me wondering why it would differ? I've never dug into a coil and looked at the guts but it would seem to me that they are all pretty similar inside(of the same type of course). In other words, I would assume the inside of both the 5" x 10" DD coils on both detectors would be about the same inside, so why would the hot spot location be different? Curiosity got the best of me.

[auminesweeper]

If a coil is made properly then the hot spot should be in the middle, you will find many after market coil have the hot spots all over the place, The early SEF coils were hotter at the back giving them a front to back wedge shaped search pattern and they could not see small nuggets of 0.12 grams some times bigger, I test all my coils and with my machines I only use Whites coils because they are uniform,in their search pattern and I don't want to have to adjust my sweep to suit them, some of those older SEF coils would only see some items at about 3 inches at the front and about 7 inches at the back so that was a huge depth loss on a 12 inch coil, I won't use coils that are uneven because it is tough enough find good things let alone have to triple your sweep coverage to make up for it,

hope this helps.

john  

[IDdesertman]

I suppose calling it a hot spot is a bit confusing, but rather the sensitivity of the coil goes out further from the center. Thus, a small nugget will give a good signal, say 1" from the front edge of the coil, whereas the other might need to be 2" back from the front edge before getting a solid signal. Not a major difference, but something that takes a bit of getting use to with a new detector.

For what its worth I was quite impressed with the Racer and expect to be using it a whole lot more. 

 

[auminesweeper]

when a coil is sensitive at the front at the front that is a good thing what I described in my first post is not the same thing as you have found with your coils, having the TIP of the coil is good thing to have for getting real close to rocks and trees etc, So I would be more than happy with that.

john

[fredmason]

I have had several e-coils. My tesoro st was sensitive right to the tip which made it great for pinpointing. On my Minelab Pi's the coiltec UFO coils were sensitive right to the tip great for pinpointing and general hunting. My NF e-coils were  not as sensitive right at the tip but about an inch in from the tip...All the coils for the Minelab were mono. I don't recall on the Lobo...

Anyway, there are definite differences between makers and coils presumably because of how they are wired. DD coils would certainly have different patterns...i think.

fred

[auminesweeper]

Yes Fred I found  that DDs can be a bit wild when it comes to there search pattern I think the Lobo were concentrics with the round ones, my knowledge is pretty limited when it comes to Tesoro's apart from they are lethal on hammered coins even after all these years.

john