PI coil, why

[Mark-VA]

Comparing the White's TDI 7 1/2" dual field coil and the Super Scan 350:
Why is the 7 1/2" coil so much better than the Super Scan. You would thing the Super Scan, being a larger coil would out preform the smaller coil, hands down.
Why.
Ohm readings are almost identical.
Could it be the number of windings?
Inductance?

Why

Both were designed and manufactured by the same company.

Actually thought about disassembling the super scan just to see.

Only intelligent answers need to be posted

[Mark-VA]

Would like to add a couple more things to my post. The actual diameter of both coils are basically the same. I'm guessing it has to be an inductance difference. Comments

[dbanner]

maybe the 350 coil was designed for a different type of searching in mind. For "niche" searching of particular kind of target. Not as general all rounder. It might perform better on tiny gold, for example.

[Carl-NC]

What is a Super Scan 350 coil? Not familiar with that one. Maybe post a photo of them side by side.

[dbanner]

I found a Super pulse 350 for TDI. Couldn't find a "Super scan" 350

[Mark-VA]

Sorry, Super Pulse 350

[Carl-NC]

I think the Super Pulse 350 is a 14" (350mm) elliptical, right? Effectively, that's a bigger coil than the 7"DF. It should hit big targets deeper, but not so for small targets. So it depends on what targets you used for comparison.

I don't remember if the SP350 is a mono or DF, that will also make a difference.

[Mark-VA]

The Super Pulse 350 is the elliptical. I bought it when Whites had a garage sale. It was marked mono. Measuring the diameter of the two coils, they look to be the same width. I use a US nickel, medium gold band, large gold band, engagement ring, small 10K white gold ring and a large class ring.
My main motive is to find the best coil for my upcoming beach trip. My last tdi beach hunt yielded some good finds, that week I was using the 12" dual field. Now that being said, my understanding a true mono coil is the best for both relic and beach hunting. That was the main reason for the comparison question. After building a 16v battery I was looking to see a good deal on improvement with the Super Pulse but didn't. But the 12" dual field had about a 30% performance increase compared to very little difference with the Super Pulse and the 7 1/2" dual field.
I guess I'd really like to know why the 12" dual field coil did so much better when using the 16volt battery over the other two coils

[dbanner]

The Super Pulse 350 is the elliptical. I bought it when Whites had a garage sale. It was marked mono. Measuring the diameter of the two coils, they look to be the same width. I use a US nickel, medium gold band, large gold band, engagement ring, small 10K white gold ring and a large class ring.
My main motive is to find the best coil for my upcoming beach trip. My last tdi beach hunt yielded some good finds, that week I was using the 12" dual field. Now that being said, my understanding a true mono coil is the best for both relic and beach hunting. That was the main reason for the comparison question. After building a 16v battery I was looking to see a good deal on improvement with the Super Pulse but didn't. But the 12" dual field had about a 30% performance increase compared to very little difference with the Super Pulse and the 7 1/2" dual field.
I guess I'd really like to know why the 12" dual field coil did so much better when using the 16volt battery over the other two coils

All things being equal, the 12 inch dual field coil also contains a 6 inch mono in and of itself. But I suspect it's the 12 inch portion of the coil that's giving the extra depth.
Also I don't think the sizes would be the only parameter. The SRF may vary between the various search coils, which could imply different capacitances, which, for a given PRF implies different currents flowing in each coil at higher voltages, which could account for varied performances. It all would depend on the individual characteristics of each coil. Just some thoughts.

[godigit1]

The dual field in my opinion is a very good coil for beach hunting and targeting jewelry. Its kinda the best of both worlds.
Deep and still sensative enough to get small jewelry.
Its been a while since I had it on the scope but its fairly fast.
Old picture dual field on a stock MPP



There are better new coils out there but If you can find a old one or used coilteck 17 x11 DD wallaby is pretty good on the TDI quite sensative for its size.

[Mark-VA]

I thought about disassembling the Super Pulse and taking the same coil windings, intact and installing it in a round housing. That way the inductance doesn't change.