lets have some coil talk on this forum

[Jackpine Savage]

tink, I liked the 3khz coil as well. I used it in some pretty heavily iron infested areas around old homesites and in empty lots where older buildings once stood with good success. Drop the sens down into the mid to upper teens on the X70 and use lots of overlap (pretend you are using a small coil). The lower sensitivity reduces the "edge effect" of targets off to the side of the coil and lets it pick silver out of iron that the small coils can at times miss. Raising the coil a couple inches off the ground works well when you don't want to have to fiddle with reducing the sensitivity.

Tom

 

[David]

trtkjd1, with the 5x10" coil in the coin and jewelry mode with tracking on and sensitivity turned down did not settle down the mineralization overloading in that (goldfields?) ghost town?? It sure should have. Try the prospecting mode in tracking with the iron mask turned up as well

Randy has also said more than once before he has tried to get Minelab to make a 6" 3khz LF coil without success. Was that in a DD or Concentric that you wanted it in Randy?

I wouldn't mind having a round 10.5" 3khz LF DD for iron infested old homesteads with large fields to cover in a day. I want to know would it be hard to pick up gold rings(or items), on old homesteads or anywhere for that matter, with any 3khz LF coil set in all metal, does anyone know? Also does gold sound off good and loud enough on the existing 9" 3khz LF Concentric coil or not?

 

[Digger]

I would settle for either small coil at 3 kHz. At the frequencies they are now, I like the DD better, simply due to what I consider to be better target separation. However, knowing that the 3 kHz coil currently available provides a distinct audio response on deep iron, I could live with a small concentric at 3 kHz. To be honest, when overlapped properly, the concentrics get better depth (around here) than a comparable sized DD. But a DD would allow me to work in the most trashy places. JMHO HH Randy

 

[tink]

Thanks for the Info Jackpine. Is there that big a difference bewteen using a 3kHz for seeking silver and a 18 kHz seeking the lower scale. I have heard people say the using a 3-7 kHz for silver definatley give you a big edge over using a 18kHz coil. As far as I am concerned you can find iron easy using any coil. But I would like to know what the actual effects a 3kHz has on silver either depth wise or solidness.

 

[Jackpine Savage]

On in the clear deep targets the lower frequency coils should give a better response. I cannot quantify the difference in exact terms, but it is there. Picking the proper coil(s) to use on a site is best done using your own experience with the detector. It is pounded into our heads on the forums that smaller coils either concentric or DD are best for trashy sites. While that is true I have never hesitated to use a large coil in iron/trash conditions as well to try and pickup a few missed targets. Target masking is our worst enemy and since each coil "sees" things a little differently they are all well worth a try.

Deeper coins on edge that are near to, but not completely masked by iron are just one example of why one should use stock or larger sized coils to help cleanup nasty sites and the lower frequencies are best for that IMO. Used with lots of overlap a "big" concentric or DD coil will find stuff the smaller coils miss.


Tom

 

[Relic]

n/t

 

[Digger]

In my opinion, the 9-inch 3 kHz concentric is very similar in depth to the TS800. At least on the higher conductive targets. I know that most people who have never used the Advantage may not believe an 8" DD coil will perform as well as a 9" concentric. But I've logged hundreds and hundreds of hours on each. And, in my moderately mineralized soil, that is the case. I find the Advantage is a bit more forgiving in faster sweep speeds. And I do like the additional information provided by TID and multiple tones of the X-Terra. But for open field hunting, I'd be happy with either combination. There are "tricks" to using either machine, to help verify targets before digging. Getting the most out of any detector/coil combination is a matter of understanding it's strong points and maximizing it's potential. JMHO HH Randy

 

[Digger]

In regard to the 3 different frequencies of 9-inch concentric coils, I don't see much (if any) difference in general depth of detection. And, any of the three will find silver, copper and gold coins. I equate what is commonly referred to as an ability to be "more sensitive" to higher conductive targets (silver and copper), is actually more useful (for me) in being "less sensitive" to lower conductive targets (iron). When you run your X-70 in all metal, with multiple tones, you can hear a very distinct "harmoneous break" when slow dragging a 3 kHz coil over a buried piece of old iron. Particularly as the iron enters and exits the detection field. The low tone is not steady and "flutters" at those audio points. JMHO HH Randy

 

[David]

Very, very good information to learn from Randy and also Jackpine Savage and tink. Talking about low frequencies. I used the 5 kHz Minelab GT 16000 VLF before 1995 when the SD PI's came out. The GT 16000 was a dedicated gold prospecting metal detector at 5 kHz!! I found small nuggets with it down to about 1 gram in highly mineralized soils. I remember my largest nuggets with the GT 16000 in 1989 were about 11, 12, and 14 grams easily sounding off. It had also had a true Auto-Trac GB about 20 years ago!!

So this is why I do not understand why Minelab does not put an Auto-Trac on the 5 kHz Musketeer Advantage(working in both all metal and discrimination)about 20 years later? IMHO it would make a great machine better but the Manual GB it has now is sufficient for most non-goldfield low mineral areas encountered for coins and relics.

Anyway the GT 16000's 5 kHz had no problem picking up small nuggets of about 1 gram at some depth in bad soils so what I am getting at, and I want know please, is with an X-Terra 70 will a 9" 3 kHz Concentric in All Metal(Coin & Jewelry) pick up small fine gold rings and fine gold chains with no problem or is there a big reduction in sensivity to very small gold items?? Does anyone have a 3 kHz coil to test this out or you have done this before and already know?

(I do not have a 3 kHz coil for my X-Terra 70 to test this out, but yes on thicker and bigger surface area gold coins it works just fine as Randy said.)

 

[BarnacleBill]

[attachment 117829 GT16000.gif]

3kHz is NOT a good choice for small gold......voice of experience. There's a reason the X70 has three different frequencies, and that is to optimize it for specific tasks. The high frequency is for prospecting with three out of the four coils for that frequency being DD's to use in high mineralization.

 

[David]

It is not a choice I am looking for Bill, a person never chooses to use a 3 kHz for small gold. But when searching out iron infested old homesteads would I still be able to find a small fine gold ring with a 3 kHz in All Metal??

When I used the GT 16000 in 1989 and then FT 16000 in 1993, I never knew what frequency it was at the time, nor did I care. I do not have those machines now. I still have a 12 elliptical for the FT 16000 in storage and at no cost, someone gave me a GT 16000 last year. The only way I figured it was running at 5 kHz was when I was looking to buy a CoilTek 15" WOT DD for my 5 kHz Musky, I saw that the 16000 used the same coil so I figured it was the same frequency as the Musky.

http://www.kamakazi.com/docsplace/coiltek/coils2.html
cl-15MD Sale $ 208
15 in. DD WOT coil for
Musketeer, 16000, Goldstriker
(Both using the same coil so I figured the 16000 also had 5 kHz the same as the Musky.)

I also wrote to Dick Shultz at Minelab to ask him if my 12 elliptical for the FT 16000 would work on my Musky and he said NO.

"No, that coil won

 

[Steve(MS)]

Fine chains are hard for most VLFs to pickup and especially if they are not real close to the coil.
You could use a static mode to find chains but if there is an abundance of other non-ferrous trash, you will certainly dig a lot of the trash.
On small fine gold rings, I am guessing you are referring to wedding bands with diamonds, most detectors can pick these up if they are not too deep, the conduct range is in the small foil up to the nickel level, say from 4 to 12 on the meter on the 70.
Of course detectors that operate at a high transmit frq should pick these up deeper but these tend to be more sensitive to nail falsing?
I understand what you are wanting to accomplish but there are always trade-offs, like advantages/ disadvantages.
Have you used the high frq 6" DD coil?
This coil will pick up tiny stuff which should favor small rings and it will hit strong on buckshot, like where I am detecting out in the cotton field, causing me to dig some of it.
As far as what the 3KHZ does since I don't have one, I will pass on trying to answer that.

 

[BarnacleBill]

Here's a post concerning the sensitivity of the 3kHz coil to low conductors. If you want to hunt fine gold with it, go for it.

http://www.findmall.com/read.php?55,431283,431283#msg-431283

Coils can be used at various frequencies depending on how they are designed. That doesn't mean they are as effective on all the various frequencies. There are trade offs with the switchable frequency detectors, which is precisely what the X-Terras were meant to overcome with a no compromise three frequency design. Each X-Terra coil is optimized for the particular frequency. Anyone hunting for fine gold/nuggets with an 8kHz detector, when higher frequency detectors 13kHz> are available needs to have their head examined.

In the following post I demonstrate, test, & establish that the 6 inch HF DD will outperform the other X-Terra coils in picking through iron, sensitivity to low conductors, and ability to see through severe mineralization, including black sand on a saltwater beach.

http://www.findmall.com/read.php?55,571137,571137#msg-571137

 

[David]

Thanks Steve, "You could use a static mode to find chains..." What is a static mode?

"On small fine gold rings, I am guessing you are referring to wedding bands with diamonds, most detectors can pick these up if they are not too deep, the conduct range is in the small foil up to the nickel level, say from 4 to 12 on the meter on the 70." YES, exactly Steve! Such rings lost around Homesteads that are iron infested. Nobody answered my question yet if a very fine small wedding band with diamonds will beep with the 3 kHz coil in All Metal? BUT both you and Bill recommend the 6 inch HF DD coil instead for this task. I thought a bigger coil with 3 kHz would be better for large fields coverage.

Thanks Bill, you have very good posts that are helpful, a person never, ever hunts fine gold with a 3 kHz on purpose but on iron infested Homesteads while looking for old silver and copper coins would I still be able to pick up a very fine small wedding band with diamonds, or there would be no signal in All Metal??

According to your post Bill, it looks like the coil to have and use is the 3 kHz for seeing below aluminum can slaw to see coins. "Only using the 3kHz coil would there be any consistent indication that a higher conductor was below the foil."

Does anyone have a 3kHz coil that they could run a very fine gold ring under it in All Metal and see what the reading number is if any and what the tone is like or broken up, thanks??

 

[Steve(MS)]

Thanks Steve, "You could use a static mode to find chains..." What is a static mode?


Static mode is better known as non-motion all-metal mode.
Different brands have different feature for their static, for instance, Whites has SAT which stands for self adjusting threshold.
On the XT-70, the prospecting mode is a static mode and it has both a SAT plus VCO.

"On small fine gold rings, I am guessing you are referring to wedding bands with diamonds, most detectors can pick these up if they are not too deep, the conduct range is in the small foil up to the nickel level, say from 4 to 12 on the meter on the 70." YES, exactly Steve! Such rings lost around Homesteads that are iron infested. Nobody answered my question yet if a very fine small wedding band with diamonds will beep with the 3 kHz coil in All Metal? BUT both you and Bill recommend the 6 inch HF DD coil instead for this task. I thought a bigger coil with 3 kHz would be better for large fields coverage.

Yes, a bigger coil will certainly help with coverage but if you are in "iron infested" places, you will need a small coil to get in between trash hopefully to make a good find.
The reason Bill and I recommend the 6 HF is because it is more sensitive to low conductors.
Also, small coils tend to hold their potential depth better than say 8" to 10" coils.
I am sure the 9" LF will signal on a thin ring but the question is rather how far away does it start to lose sensitivity to the ring.
It could be that the 9" LF would do what you want provided the lost ring isn't very deep or surrounded by too much trash.
If the ring is surrounded by trash, the 6" DD is definitely the way to go.
Today while using the 6DD, I got a 10 to 12 reading so I figured to dig it up, it turned out to be buckshot down 4" in the ground, now that is what I call sensitive to low conductors.
HH.

 

[Digger]

As you can see in the picture, it is a very thin gold ring with a small ruby. I found it last year with the X-Terra 70 and 6-inch DD coil. In the picture, it is next to a US dime so you can get an idea of it's size. [attachment 117929 goldring.jpg] When airtesting it tonight, I find it reads a solid TID of 8 when using the all metal mode. Switching to the 9-inch concentric at 3 kHz, it bounces a bit between 4 and 6. Depth wise, it will hit at 4.5 inches on either coil. However it locks on better with the DD. If we hadn't just received another 7 inches of snow yesterday, I would have done the testing outdoors. But this will have to do for now. HH Randy

 

[xwyokid]

Found this with the 5x10.

 

[David]

Thanks xwyokid!

6-inch DD coil vs 9-inch concentric at 3 kHz on a fine small gold ring

Randy wrote:
"When airtesting it tonight, I find it reads a solid TID of 8 when using the all metal mode. Switching to the 9-inch concentric at 3 kHz, it bounces a bit between 4 and 6. Depth wise, it will hit at 4.5 inches on either coil. However it locks on better with the DD."

Thank you, for doing that test for me Randy it is appreciated! Shows to me the 9-inch concentric at 3 kHz WILL detect and find a fine small gold ring with the LF. Also will find small gold nuggets, if need be, if they ever make a 3 kHz DD someday.