Which frequency coil for the wet-salt beach ?

[Tom_in_CA]

Hey gang, I'm shopping for a 705, to use in iron-ridden ghost-townsy type environments. Because when used with the HF 6" coil, it seems to do quite well at seeing through iron. And am wondering if the machine would work at a backup, for if I ever intended to use it on regular turf, beach, etc.... And for comparison sakes: My main machine of choice for turf and the wet beach, is the Explorer II. Ok, so here's the question:

I notice that the 705 has auto-track. As opposed to the 305, which doesn't. I'm assuming that the HF coils would not be well-suited for moderate to high mineralized beaches, right ? But how about the mid frequency and low frequency coils ? (3 and 7.5). Which of those is best for moderate-mineral wet-salt beaches ?

For purposes of this question, the 2 factors are:

1) ability in wet salt minerals

2) does the lower frequency 3kHz retain sufficient ability to pick up smaller gold items (earings, etc...) on the beach ? Or does the fact of going to a frequency this low , mean it will favor high conductors , and start to wain on the lower conductors ?

 

[Old Longhair]

Wet salt is problematic for all single frequency VLF machines. The 705's Beach Tracking mode can help, and Prospecting mode is also worth a try.
With a 3kHz coil you can kiss all small gold goodbye. Larger pieces it will find, but small stuff just isn't discernible from iron with that frequency. I would stick with HF or MF DD coils, HF being the most likely preference.

 

[Tom_in_CA]

old-long-hair: thanx for the answer. Yes I realize that a 705 will never compare to an Explorer (or sov, or excal, etc...) on wet-mineral-salt. Hence it's not meant for wet beach hunting.

I was just thinking that since it's got auto-track, and since a LF coil is available, that it might suffice. But it sounds like you're saying that even with the LF coils, and auto-track, it still leaves room-to-be-desired on the wet beach, eh ?

Ok then: How about for land hunting on turf? If a person was the mid frequency 7.5 kHz , how would he do in turf for silver, when compared to the main-stay explorers ? Or would the 3 kHz be a better choice at turf ?

 

[Old Longhair]

For inland hunting for high conductors like silver and copper 3kHz is the hot ticket.
The MF coils are a good all-around choice, and the most honest across the detection range due to their virtually uniform target segment bin widths.
To understand target segment bin assignments by frequency better, check out page 82 in the E-Book.

 

[Tom_in_CA]

Ok. Great info. A few followup questions:

a) if the 3 kHz is the "hot ticket" for turf-hunting high conductors, then 1) how would it compare to depth, with commensurate coil-sizes, when compared to the Exp. II for turf ? 2) and even though it's not going to be as "hot" on low conductors, I'm assuming it can still effortlessly get nickels, right ? (if a person elected to chase low TID targets too) , right ? Ie.: the ones it will start to waffle on is going to be smaller lower targets like foil, little charms, etc.... right? But nickels still sufficient, right ?

b) I have seen first-hand how the 6" HF coil was deadly in seeing through and around iron, in ghost-townsy type iron-ridden sites. But how would that same coil do in something like this: Underneath old bleacher-grandstands, where the objective is not-so-much "seeing through iron", but also in seeing through and around foil, tabs, etc.... to get high conductors in those type sites? I typically reach for a 2-filter machine like a silver sabre for such tasks. But how does the X-terra compare in such tasks? Can a person put the disc. up high enough to knock out tabs (for examples), and still get coins hiding next to or under the tabs & foil ?

 

[Old Longhair]

Okay...
a) - 1) About the same as the Exp II given commensurate size coils. 2) Not very good on nickels. Nickels take a lot of practice to learn to interpret the combined audio and ID to be consistent with a 3kHz coil, because they are such low conductors.

b) Target resolution on high conductors suffers with the HF coils (again due to bin widths). Under bleachers it would be fine for cutting out foil and iron, but it will find you more folded over pull tabs, nuts & bolts, and crown caps than you ever knew existed.

 

[Tom_in_CA]

N/T

 

[oneton]

I would say it will find everything the exp 11 will find