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9" 3 kHz Coil for relics?
- Thread starter Canewrap
- Start date
Reconmarine1984
New member
The 10.5 DD Freq. 7.5 is by far the only coil In use for Relic Hunting. I used 9 inch 3 Freq. which little deeper than standard coil. But Overall The 10.5 DD Coil is best on depth and super stable!!
nero_design
New member
Relics? Yes. But the main advantage is as follows: The lower frequency coils are better for greater depth whereas the higher frequencies are more sensitive to smaller targets. Lower frequencies tend to give you the best depth so this 3kHz coil should enable the user to find all sorts of targets that are possibly just out of range of the other frequency coils. I think you'll find the 3kHz coil is going to be particular sensitive to Silver so it's going to the the coil of choice for people hunting for Silver Reales (for example) in areas of Florida and the Bahamas. Most of those coins tend to be thicker than most other types found elsewhere in the world and, in many instances, larger.
But don't think that this is a coil that is only useful for certain types of metal... Any detector can find metal. This coil finds most metals at somewhat GREATER depth compared to the Medium and High Frequency coils. I suppose it could be used anywhere that you wanted good depth for average to large items. For smaller items, or items in mineralized soil or salt water sands, the higher frequencies are going to be favored. Since many coin & relic hunters don't have to contend with such soils (especially in central Europe), this coil will be favored by them. I can see them being used on the beaches too since this is a waterproof coil and it should still handle saline water fairly well in Beach Tracking Mode.
[size=small]Silver Spanish 8 Reale from 1770. My coin but not my find.
Found off the coast of Florida by a US treasure hunter
This would be ideal for the 3kHz coil at depth due to the size.[/size]
But don't think that this is a coil that is only useful for certain types of metal... Any detector can find metal. This coil finds most metals at somewhat GREATER depth compared to the Medium and High Frequency coils. I suppose it could be used anywhere that you wanted good depth for average to large items. For smaller items, or items in mineralized soil or salt water sands, the higher frequencies are going to be favored. Since many coin & relic hunters don't have to contend with such soils (especially in central Europe), this coil will be favored by them. I can see them being used on the beaches too since this is a waterproof coil and it should still handle saline water fairly well in Beach Tracking Mode.
[size=small]Silver Spanish 8 Reale from 1770. My coin but not my find.
Found off the coast of Florida by a US treasure hunter
This would be ideal for the 3kHz coil at depth due to the size.[/size]
nero_design
New member
Wait for Digger to reply when he pops by the forum. I think he's actually used the 3kHz coil recently and commented on the depth ...so he'll be able to tell you more. There's actually very little information about this new coil online. I'm thinking this might be your best choice for larger items if you're relic hunting, but wait for Digger's observations. Cheers!
Funny thing is, it doesn't have to be a nose heavy detector with these coils if they would just move some weight back under the arm. My MXT is over a pound heavier than this machine, yet its better balanced. I'm in the process of doing some mods to the rods on my Xterra 70 to make it less nose heavy. I'll post how it comes out when I'm done. I'm cutting a little weight out of the mid rod, while shortening it a little and adding some weight inside the rod, back behind the arm rest. I expect this to make it easier to swing the 10.5" DD coil and eventually when I get a 3 kHz it should help with that as well. I really don't know why Minelab is so resistant to change. Seems to me that if they changed something like this they'd sell more machines and they really need to make the shorter lower rod a standard rod and not make everybody buy or mod theirs to get it right. I guess the market for these kind of metal detectors is not all that big so its hard to recoup the costs. I wonder if the days of well engineered, well-built detectors is over and what we're going to increasingly see is the cheap mass produced junk being peddled by the big retailers.
I have had the 7.5 kHz 10.5 DD coil and now have the 18.75 kHz 10.5DD To me in my ground, the higher freq coil is deeper on brass & lead. Look at the coil chart in the FAQ section. And when you think about it, the Tesoro Tejon is at 17 khz and people swear by the depth and performance of it. I have dug 3 ringers and coat buttons at 12" in rocky ground here in Missouri. Also the TID of the Xterra usualy reads in the 40's when I get a deep signal. I hunt in 2 tone, all metal and use auto trac ground balance also...............MO
I am a big fan of the 3 khz coil. In my opinion, it is my "go to coil" for hunting the open fields around old farmsites and homesteads. Theoretically, lower frequencies are more sensitive to larger, deeper targets as well as targets with higher levels of conductivity. (silver copper etc) Conversely, the higher frequency coils are better suited for smaller targets and those with lower levels of conductivity. (gold etc) With that said, I don't see much difference in the depth of detection between any of the three 9-inch concentric coils. And I can't prove that the 3 kHz is more sensitive to targets with higher levels of conductivity. Again, any of the three will find silver, copper, gold, lead and brass, with very little difference in depth of detection. However, I do find that the 3 khz provides a very distinct audio response on deeply buried iron. As one who hunts in multiple tone, all metal mode, I listen to everything, ignoring the low tones of ferrous targets. What I have found is that iron gives a broken tone at the edges when using the 3 kHz coil. And, is far less likely to provide a consistent audio tone on deep iron. Especially when working the coil around edge of the target, listening for variances in the pitch.
Again, I won't say that the 9-inch, 3 kHz concentric is any deeper than the 9-inch, 7.5 kHz concentric. But I will say that the distinct audio response of iron is much easier to decipher using the 3 kHz than it is the other two frequencies. It has saved me digging a ton of old farm implements! JMHO HH Randy
Again, I won't say that the 9-inch, 3 kHz concentric is any deeper than the 9-inch, 7.5 kHz concentric. But I will say that the distinct audio response of iron is much easier to decipher using the 3 kHz than it is the other two frequencies. It has saved me digging a ton of old farm implements! JMHO HH Randy
Digger(Randy), excellent, that is one of the best posts I have ever read.
I totally agree the 3 kHz concentric coil is a must have around old homesteads in iron infested areas in peat soil and deep black dirt(not highly mineralized).
Iron has been my enemy for along time and the best way to combat it is with the lowest frequency.
The lower the frequency(3 kHz) it is more sensitive to copper and silver and less sensitive to iron and gold.
The higher the frequency(18.75 kHz) it is more sensitive to iron a gold and less sensitive to copper and silver.
I sure wish they would make a 3 kHz 10.5" DD soon, for super stability in high mineralized ground looking for silver and copper with alot of iron in it while not prospecting for gold.
Randy, if I hear you right, you hunt in All-Metal on the 70 in old homesteads??
I totally agree the 3 kHz concentric coil is a must have around old homesteads in iron infested areas in peat soil and deep black dirt(not highly mineralized).
Iron has been my enemy for along time and the best way to combat it is with the lowest frequency.
The lower the frequency(3 kHz) it is more sensitive to copper and silver and less sensitive to iron and gold.
The higher the frequency(18.75 kHz) it is more sensitive to iron a gold and less sensitive to copper and silver.
I sure wish they would make a 3 kHz 10.5" DD soon, for super stability in high mineralized ground looking for silver and copper with alot of iron in it while not prospecting for gold.
Randy, if I hear you right, you hunt in All-Metal on the 70 in old homesteads??
I hunt in all metal mode, with multiple tones. With all the pitch variances generated by multiple tones, I can hear individual targets with much more clarity. Even though I typically ignore the low tones of ferrous targets, iron breaks off in pitch as you drag the coil away from being centered on the target. And coins (etc) sound off loud and clear. I won't say I have all the tones "memorized". But it sure don't take long to refresh my memory when I get on the hunt.
For those of you who haven't tried multiple tones, let me give you an experiment to "sharpen" your skills. I used my 6-inch DD at 18.75 kHz for these results.
Take a few dimes and read them individually. Pull out four of them that each read exactly 38 on the TID. Now, lay them down in a row, each about 8 - 10 inches apart. Notice when you sweep over them, they each read a high tone and register 38 on the TID. Now take the two middle coins and lay them so they are touching each other, leaving the two outside coins as they were. Now, sweep over the two coins in the middle and check the TID. If you dimes are like mine, when they are together, they will now read a 36 instead of the 38 they read when they were separated. (Hmmmmm? still working on that reason as my White's adds them together) Even though they now read a 36 when combined, didn't you still get a high tone? You should have. Now sweep over the single coin, the two coins, and the other single coin AND you will hear why I like the multiple tone mode. The tones produced by the single dimes reading 38 is a higher pitch than the tone produced by the two "touching" coins reading 36. It is tough to tell the difference when they are read "one at a time". But when you lay them out like this, and sweep over the three target masses, it is fairly easy to distinguish the difference in tones. This can be done with any denomination of coins you have. Quarters, dimes, pennies, nickels etc. Just find two of the same denomination, that read differently on the TID, and you'll hear the difference on audio as well. HH Randy
For those of you who haven't tried multiple tones, let me give you an experiment to "sharpen" your skills. I used my 6-inch DD at 18.75 kHz for these results.
Take a few dimes and read them individually. Pull out four of them that each read exactly 38 on the TID. Now, lay them down in a row, each about 8 - 10 inches apart. Notice when you sweep over them, they each read a high tone and register 38 on the TID. Now take the two middle coins and lay them so they are touching each other, leaving the two outside coins as they were. Now, sweep over the two coins in the middle and check the TID. If you dimes are like mine, when they are together, they will now read a 36 instead of the 38 they read when they were separated. (Hmmmmm? still working on that reason as my White's adds them together) Even though they now read a 36 when combined, didn't you still get a high tone? You should have. Now sweep over the single coin, the two coins, and the other single coin AND you will hear why I like the multiple tone mode. The tones produced by the single dimes reading 38 is a higher pitch than the tone produced by the two "touching" coins reading 36. It is tough to tell the difference when they are read "one at a time". But when you lay them out like this, and sweep over the three target masses, it is fairly easy to distinguish the difference in tones. This can be done with any denomination of coins you have. Quarters, dimes, pennies, nickels etc. Just find two of the same denomination, that read differently on the TID, and you'll hear the difference on audio as well. HH Randy