COIL QUESTION

[kneedet]

it is my understanding that larger coil will go deeper only on larger targets. so if I want to go deeper for jewlery will the larger coil matter or will higher frequency give me more depth. thanks

 

[DirtAngler]

Usually a larger coil will give increased depth. You must also consider that a DD coil will do better in more mineralized ground. As far as frequency, lower frequency will hit better on silver, higher frequency on small jewelry and gold. This is a general rule of thumb. Sometimes smaller coils will be much better where targets are masked or the ground is littered with metal trash.

 

[kneedet]

will you loss depth when using a high frequency coil

 

[h2oyo]

Its my understanding that the small coil wont go as deep as the larger ones. I used a 4 inch coil on my whites in parks that are really trashy. It does help find items between all the trash. I was told that you may loose a little depth but its the trade off and the depth is minimal.
H2

 

[kneedet]

but does frequency have anything to do with depth?

 

[TerraDigger]

"but does frequency have anything to do with depth"

Yes it does. As a general rule, with single frequency detectors, as mineralization increases coupled with an increase in the operating frequency of the machine = less depth

 

[kneedet]

"but does frequency have anything to do with depth"

Yes it does. As a general rule, with single frequency detectors, as mineralization increases coupled with an increase in the operating frequency of the machine = less depth[/quote
So assuming there is no mineralization and two of same detctors with same size coil will the one with lower frequency coil go deeper?

 

[JimGilmore]

it's realitave.. if you expecting to find the back of a gold earring. going bigger on coil size is unllikely to help. because as the coil get bigger the object is going to becime an even smallersize compared to the sample size.
Now if we were looking at a large enough object for easy identification with a small coil. then a larget coil will usually get more depth. Providing the masking of multipl targets is not going to affect the signal.
So going big is not a straight simple answer.Your better to start small and reduce discrimonation. removing all signals and then go to a bigger coil.

 

[Critterhunter]

As a general rule of thumb I've found that a concentric's max coil size to still be sensitive and show more depth on coin sized targets is about 10". Any bigger and they don't seem to hit as good on coin sized targets so they don't show an increase in depth, at least in my somewhat mineralized soil. Now, some say about 12" is max concentric size to still see gains in depth, but I bet that's in good low mineral soil. DD coils tend to hold their sensitivity to coin sized targets as they get larger, and also see less ground so they handle the minerals better at those bigger sizes. I always guessed by reading posts that about 14 to maybe 15" was the max DD coil size to still show improvements in depth on coin sized targets. However, I found the 15x12 got less depth in my soil on a dime than even my stock 10" coil. Just seeing too much ground signal and washing or degrading the target out with it, even though it would run at very high sensitivity settings....As I found a lower setting gave better ID at depth in my soil with it. The 12x10 does show improvements in depth over my stock 10" coil in my soil, so I'm now guessing either 12 or 13" is about the max size a coil can be in my soil and still show improvements in depth on coin sized targets. The 12x10 has such a sharp and less "fuzzy" field that I feel it actually rides on and sees less ground than even my stock 10" coil, so I'm not even sure a round 12 or 13" coil might show increased depth over my stock 10" coil because conventional round DD coils will see more ground signal than the 12x10 in my opinion. Some guys even say in really bad soil their 8" coils get more depth than their 10" coils.

 

[Tom Slick]

Usually the lower the frequency, the better the depth if using the same size coil. The frequency is not determined by the coil. In other words, changing the coil size or shape doesn't affect the the frequency. A higher frequency usually allows a detector to see smaller targets. As an example: 2kHz will go deep on silver and copper coins, 15kHz will get good depth on gold jewelry like rings, 50kHz will detect very small gold nuggets near the surface. Manufacturers use frequencies that will be a good compromise based on what the detector is designed to do. Gold nugget detectors usually run an 20kHz - 60kHz, general detectors for coins and jewelry about 10kHz - 20kHz, and coin machines from 2kHz - 10kHz. (all kHz's plus or minus a few kHz's). Also, lower frequencies handle higher mineralization better but then you get into the difference between factory set ground balance verse adjustable ground balance (either automatic or manual).

 

[gmanlight]

Keep in mind larger coils will see more ground and trash at the same time.
Not a big deal at the beach or open fields , but in Hi trash it can be a problem .