Questions about the 3 kHz coil....

[Ed in Mo]

I am debating on weather to buy one or not. I am as most would call a coin shooter. But the more I think about it the more I get confused. Maybe some of you all could help me understand and finalize my decision.

If the 3 kHz is more sensitive to copper and silver, then is it less sensitive to iron and metal or aluminum...such as trash? And how does it react to clad coins then? I realize it is not as good for gold, but can a ring/coin still be found, with in reason, based on size or depth?

I hunt older farm houses and a lot of parks as well. When I hunt parks tho, I usually hunt the "out of the way spots" that seem to have less trash. I am currently using the 10.5 DD, 7.5 kHz....and I am happy with the result from it. But, hunting some of the parks around St. Louis area is a challenge and would love to find that edge over some of the other hunters.

With running a pattern mode, which I normally do, would the 3kHz coil still be a advantage to me? And would it be wise for parks? I do not use the all metals mode as often as I would like. Seems to be more noise than I can handle, but I plan to use it more as time goes on.

Any and All comments are appreciated, Thanks all!

 

[crow-duck]

I would wait till they come out with the small coil.Did you get the standard coil with you x-terra if so use it.Just my thought.
crowduck

 

[NH Bob]

I agree with Crowduck, the small coil will be out soon.
The 3 khz as I was told is more of a relic coil. Digger likes it for coin hunting and likes it. It will sound off on higher conductive metals and that would be Med. sized to big iron and all aluminum.

 

[BarnacleBill]

This post might interest you.

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

My view/position "at the moment" is that it provides it's greatest benefit to me by ignoring shallow foil, rather than seeing higher conductors deeper or providing better discrimination.

As a prime example I relate the following. I have permission to hunt a children's summer camp where there are about 40 picnic tables adjacent to a dining hall. These tables appear to have been in the location for decades, so you can imagine the foil/tab/cap situation. Having hunted the area with the HF & MF coils, the foil response was pronounced. Then one day experimenting with the 3KHz to see if I could go deeper after higher conductors, I traveled through this area.

What I noticed was how much quieter it was, at first I thought there was something wrong with the coil or my settings. So I ran a few quick checks, burying a coin etc. After using the coil further there, it was much easier to "hear" the coins as the noise clutter was greatly reduced. I plan to go back this fall for more work in that area to further confirm my initial impression.

Even after a year, I am still experimenting to exploit the many facets the X machines can provide. Remember this is just my take on one aspect of the 3KHz X70 combo, others can probably tell you how they feel about their part of the elephant.

HH
BarnacleBill

 

[Digger]

Ed, I really - REALLY like the 3 kHz coil for coin hunting. Bill linked you to an excellent post he had made concerning foil. And I have made several posts concerning the sounds of iron with the 3 kHz coil. I encourage you to do a search of 3 kHz on this forum to get varying opinions.

To answer your questions, lower freq = higher conduct. And higher freq = lower conduct. Since TID is based on conductivity levels, the X-Terra will read a US clad coin the same as it reads the same denomination in a US silver coin.

As far as helping you gain an advantage over other detectorists at the local parks.... my opinion may differ from others. But you asked for opinions. I honestly believe there are more old coins hiding out there due to being masked by an adjacent piece of trash than due to depth beyond the reach of our coils. If you are stuck in the Pattern mode, you won't find many of them regardless of the coil you are using. If they could be found using much discrimination, they wouldn't still be hiding in the park! I have been using the all metal mode for over a year and have learned to filter out the tones. I recognize it may be easier for me because I seldom hunt modern parks. The trash in the places I hunt is usually iron. But to be honest, I believe you would benefit more from using a smaller than stock coil as opposed to shifting frequencies. And, reduce the number of notches you are rejecting and simply dig more signals. Especially those with mixed tones or deep readings. Unfortunately, the smaller coil isn't here yet. If you have the money for both, buy a 3 kHz now and buy the smaller coil when it is available. If you can only budget for one at this time, I would wait a bit longer for the smaller coil, regardless of the frequency.

One last comment on coin hunting.... take a different approach, literally. Don't always go the same direction when hunting a park. Observe the "traffic flow" and hunt perpendicular to the direction that people walk. Then hunt the same area at various degrees of approach. In other words, hunt it diagonally from several directions. You will be swseeping those targets from a different angle than others may have in the past. And it might just be an angle that lets you coax that old seated dime out from that bottle cap, instead of being masked. Most of the places I hunt, I have the luxury of being the only one to hunt it. That is not because of luck or because there are not any other detectorists around here. It is because I spend a lot of time researching and target spots that others may not have found. Quite honestly, when you find a wide-open, out of the way site like that, you could find those coins with many detectors being used today. But even in those sites, I use the X-Terra because I like the weight, balance, large LCD, adjustments and features for those sites. And, when I revisit those sites, even though I may be the only one hunting it, I walk across it at a different angle.
This is even more important when you hut areas that others are hunting. Approaching those suspected targets from a different direction is one of the most productive changes you will make to your technique. Detectors are an important tool, as are coil design, sweep speed, discrimination settings etc. But don't let yourself get caught up in hunting the same area, going in the same direction, every time you go to the park. Take that "different approach" and you might be surprised what you find. HH Randy

 

[NH Bob]

Hi Digger,
I had the 3KHz and 7.5KHz DD coils with my first X70 and sold it to Bavaria Mike last fall. Never used the 3khz but one day.
The more the subject of this coil comes up the more interested I get. I hunt like you, for old coins and relics.
I just ordered the 3KHZ coil about an hour ago. and its you and Bills fault I have a question for you and who ever wants to contribute.
First, the Beer caps that come in like a quarter here are a real pain. you have to dig them, specially when they are deep. They sound sooo good. How does the 3khz handle them? Is there any difference from the 7.5?
Second, How much of the lower conductive items get ignored? Where I hunt as with you there is always a chance for a small Gold coin.
And third, How easy or hard is it to recognize big iron over silver or a Large cent. In a side by side scenario with the tone. In other words, is the iron a different type of high tone than the silver or Large??
Thanx for any help that I get on these questions. I also know that Bavaria Mike would be much interested too.

 

[Digger]

The 3 kHz coil isn't a magic fix for any of the items you mentioned. When you have a detector that bases it's TID on conductivity, my opinion is that when the conductivity range and approximate size of any target matches that of a coin, it will likely appear as a coin on your TID. But, let me elaborate on each of your questions.

First, the Beer caps that come in like a quarter here are a real pain. you have to dig them, specially when they are deep. They sound sooo good. How does the 3khz handle them? Is there any difference from the 7.5?

There are lots of variables on bottle caps. I have one old fair ground I hunt that includes some caps that I just can't ignore. I have come to the conclusion that they were either manufactured during War time and the metallic content is different than most others. Or, they are some sort of "home-brew" and not mass produced caps. Regardless, they seem to have lots of surface rust but not much deterioration. In other words, they are round, the core is still solid, the outside has leeched into the ground and they have a metallic content that resembles a quarter. At least they fool ALL of my detectors into thinking they are quarters. All I have been able to do at this site is to take a depth reading and not dig the targets less than a couple inches. Actually, I can't do that! I still dig them and find that anything less than two inches is one of those darn caps. The 3 kHz coils doesn't lock on to them as tight as the 7.5 coil. But still enough that it could be confused with a coin on edge.

Second, How much of the lower conductive items get ignored? Where I hunt as with you there is always a chance for a small Gold coin.


The lower conductive targets don't really get ignored. They still beep and they still register on the TID. In 4-tone, all metal, their low tone just isn't as predominate as it is with the higher frequencies. Nothing scientific to base this on. Just my hearing. I swear I can hear a more abrupt start and stop on the tones with the 3 kHz. Not a smooth transition as I hear with the 7.5 or 18.75. I don't have a 2 1/2 $ gold piece, or a $1 gold piece to test with. But my $5, $10 and $10 gold pieces lock on hard. The 3 kHz coil may not be tuned to be as sensitive to small gold coins. But I don't think the minimal difference between 3kHz - 7.5kHz and 18.75 kHz is going to cause you to lose any gold coins with the 3kHz coils.

And third, How easy or hard is it to recognize big iron over silver or a Large cent. In a side by side scenario with the tone. In other words, is the iron a different type of high tone than the silver or Large??

For 35 years, I have been "avoiding" those nasty old large cents. Since my part of the Country wasn't settled until the mid 1850's, all I find are those pesky IH cents. But, I have found some large silver. The pieces of iron that are round (I call them horse rings, pic attached) are very difficult to differentiate from large silver when they are in the ground. Sizing with the Prospect mode doesn't help a lot on targets the size of some iron rings. A bit different story once they are exposed. But in the ground they come in at 44, 46 or 48. Flat pieces or odd shaped pieces are not such a problem. The ID may indicate a big piece of silver. But when it is a sizable target, I flip to Prospecting mode and get an idea of the size and shape. If the target is coin sized, I dig it. If it is long and narrow or HUGE, I leave it in the ground. Those I dig are usually either coins or more of those horse rings. I have a theory on the round iron rings.... I dug an iffy signal when I was first testing the X-Terra. (wanted to see what everything was). It turned out to be half of a rusted horse ring. My theory is that, when a target is round and iron, it will be hard for any detector that bases the TID on conductivity, to tell them apart from coins. When it is broken, it can get a better idea of the composition. You can see a similar thing with gold jewelry. Rings whose bands are intact will read one way and those with broken bands will read much lower. You can prove this if you have a ring with a broken band. Read it with the band separated and you will get one reading. Hold the broken ends together and you will get a much higher reading. Same metallic content and same size and weight. The only difference is the complete circle of the round ring. Similar findings to what I have learned with those darn horse rings.
HH Randy

 

[NH Bob]

Do you notice any better depth??
You prefer the 3kHz over the others for a reason.
Excuse my choice of wording. This is usually what people missunderstand about me. Thats why I took my grumpy face off and put the coin on.

 

[Digger]

I haven't found any coins using the 3 kHz that I couldn't have found with the 7.5 kHz due to depth. But I have dug less iron using the 3 kHz, due to the audio differences I mentioned before. And, I am convinced I was able to "unmask" several old IH cents from iron infested ground that I wouldn't have with the 7.5 kHz. So as to not leave any frequency out, I don't use the 18.75 kHz much because the sensitivity is too hot for the types of places I hunt. If I have to lower the sensitivity of the detector to compensate for a "hot" coil, then what is the point if I am coin shooting for silver and copper? When the X-50 and X-30 were introduced, all I used were the 7.5 kHz coils. In fact, if you search the first 12 months of posts, you will likely find some posts I made saying that I preferred the 7.5 and couldn't tell much (if any) difference in comparing detection depth between coils or detector models. For the most part, I still feel that way about the three detector models. However, just as with the X-70 itself, the more I use the 3 kHz coil, the more I like it. Theoretically, the 3 kHz coil should be more sensitive to copper and silver. And, I swear I can hear a subtle difference in the audio produced by iron targets with the 3 kHz coil than I can the other two. So, to "not really" answer your question again, I guess it is just my preference based on my hearing the tones and interpreting them. That and I want that low freq/high conductivity theory on my side! HH Randy

 

[OldeTymer]

Here is a link to some X-Terra tips on the Minelab Owner's website, if you haven't seen them, that might help this discussion:

http://www.minelabowners.com/xterratips.pdf

I found the information quite useful.

Good hunting,
OldeTymer

 

[NH Bob]

n/t

 

[NH Bob]

n/t

 

[Ed in Mo]

I will order mine in the morning. I think it is something worth checking out and it was made for a reason. It has been haunting me for weeks now and was hoping no one would talk me out of it. The link you gave is very good reading as well, explained a lot. Thanks for all the great info guys, you all are great!

 

[Jackpine Savage]

Hi Ed,

I think you will like the 3 Khz coil for your use I found it to be a very versatile coil. Its great for covering the fringe areas for the deeper older coins IMO. With high sensitivity settings it has a fairly wide sweep pattern down to decent depths but you still need to overlap to get the deeper coins. For the iron trashy areas simply reduce the sensitivity, slow down and increase the overlap of your sweeps (pretend your using a smaller coil). I was amazed at how it pulled coins out of iron at a couple sites by using lots of overlap.

Tom

 

[Wirechief]

I had to wonder about using the 3Khz coil for awhile but finally installed it at the end of last Summer and haven't taken it off since. I realized in a hurry that I had more depth over the 7.5Khz coil and still had the sensitivity for coins. I went back over some areas that I had used the medium coil on and found more and deeper coins with the 3Khz coil. I also work these small areas from all directions too. So the 3Khz coil is worth the money and not useless as I read on one posting. Happy huntin all and God Bless.

John Tomlinson,CET
John's Detectors