Hunting old coins in bad ground

[Daniel Tn]

I was wondering if anybody had any setup tips or techniques for coin hunting in ground that isn't so metal detector friendly.

Here is what I am running into: If I am out in the field, running manual sensitivity, with any setting above 12 or so, I get more the less a constant threshold null if I am running any discrimination pattern. If I run an open pattern, then it is a rapid fire machine gun of iron grunts. At the first site I hunted, I assumed that it probably was iron in the ground. But this has been at every site I have hunted thus far...including the majority of sites that I have been to with previous detectors. Including pulse machines...which ran smooth and did not encounter the thick iron like the CTX leads you to believe might be there.

So I began trying different things and ultimately, put the machine in auto sensitivity just to see what it would do. Well in auto sensitivity, the machine only wants to run at about the 6 to 8 level. BUT...the threshold is smooth as can be, and there aren't any of those iron grunts. Even over the same ground. So I know it has to do with the ground being highly mineralized.

The problem with running the machine in auto, and only getting it to around 6-8 in sensitivity...is obviously the depth loss. In this soil, I can take a silver dime and bury it at 5 inches...and with sensitivity on 6 or 8, that dime is non existent. I can bump the sensitivity up in manual and get it to pick the dime up, but at the same time, I am living in that constant null range to be able to do it. I was wondering if any of you had ever encountered soil like I am describing, and what you did to hunt in it.

I'm hunting old sections of town....mostly vacant lots, parks, etc looking for silver coins. I have all 3 coils for the machine and am going to try the 6 inch coil tomorrow in one of the same sites, and see if it goes any higher on the auto sensitivity with that coil.

Other wise, I am running the machine in the "training" programs that I downloaded from here at Findmall, and have been tweaking on things of my own.

I have always been a relic hunter, and just recently got the CTX and wanted to get into hunting old coins. We deal with the same soil in relic hunting and we have learned to either go with pulse machines or to hunt in all metal mode. The bad thing about this type of soil is that it generally masks the better finds...no matter their conductivity...and makes them read WAY lower than what they might normally read. For example...a civil war bullet will ID into the zinc penny range on most detectors. In this dirt...bullets often read down into the iron or foil range if they are past 6 inches deep. So I have a bad feeling that silver and copper is probably going to do the same thing...meaning that getting a proper ID on them will be very tough and might even be impossible. In the sites I am hunting now, it is not possible to dig everything like we do when relic hunting.

 

[oregon_dragonfly]

I will try to describe how I have mine set up on the screen first I have the first bottom boxes blanked then I have the right corner blanked off about 5 boxes up and 5 boxes from the right and form a stair step to the right 5th one to start with that and fill in or remove as I go then I run ferris coin, and watch the screen because there will be times you will get a good number with no noise when working in iron with multiple targets I also have the sound set to 5 tone and move them to separate copper, silver, nickels, and iron where they mostly hit with silver hi and iron lo but this is a personal choice and has nothing to do with performance. I run in manual as high as I can push it, but auto +3 works also. but most of all if you are in a lot of trash use the 6'' and go slow. an if it sounds ify dig it it is better to dig up a little trash than walk away from a treasure, and besides you will find out why it is acting that way so next time you will know..and I use the exchange to set every thing up, it's a lot easier and download it to your machine dfly

 

[Chris(SoCenWI)]

Danial,

This has been discussed on the Minelab explorer series forums for a decade and a half. I own an original XS and the CTX. I almost always hunt ferrous open screen with manual sensitivity as high as stable. At almost all the sites I hunt I also hear a constant drum of low conductors, (or constant null if any iron discrimination is used) Over the years it was assumed by many that this noise was the detector reacting to ground mineralization.

I'm not so sure; I think it may be that there really is that much iron junk in the ground. Up at our lake place built in the eighties I was putzing around with my detector, near the cabin the familiar sounds, but once I got farther away from the building site pretty much a rock solid threshold. This is ground that has never been built on, never farmed, pretty much the only signals you get are few and far between shell casings. The ground near and farther from the cabin is the same soil type, but huge difference in the back ground noise. There have been a few other sites where I can detect with a fairly constant threshold at higher sensitivities but they are few and far between and almost always out in the sticks. (I'm wondering if presence of EMI- electrical noise from power lines- may also play a part).

Long story short when detecting in town or around any sort of building site, and even in many fields, the machine gun iron grunt sound is the norm. And like you say in Automatic modes the detector will detune itself to try maintain a more constant threshold and this can result in a huge depth loss. Before the Etrac and CTX there was no way of know what the actual sensitivity was in Auto mode and there were a great many debates on what was going on and whether it mattered. I don't think there is much you can do. In highly mineralized soil you are definitely limited on how deep you can detect and/or ID a target. In high iron trash, but milder mineralization I still run the sensitivity as high as I can. Depending on the angle you hit a target at you can still sometimes pick up deep finds between the nails, but the majority of the targets are still probably masked by all the other junk.

Chris

 

[foreign object]

I think the small coil will help a good bit. Also if your auto sensitive is running 6-8 try switching to manual and run 10 points higher. 16-18

Not sure if you are using GB or not but try both ways and try ground coin instead of ferrous coin.

I have read where some guys use the saltwater water setting also in bad ground.

 

[Daniel Tn]

I don't doubt what you are saying at all, and you may indeed be correct. I'm gonna say that I've ran the Whites TDI machine in some of these same spots, and if there was a piece of iron anywhere around, that TDI would latch onto it. It's an iron magnet, especially small iron and nails. The thing I noticed about the CTX is that when its doing these iron grunts I spoke of, they will not be a repeatable signal...not one you can move the coil back and forth over and pinpoint, like you can do if its actually an iron target in the ground. That's what leads me to believe that it may be the ground noise in a lot of these places.

I have dug a great amount of trash so far, even running a small discrimination window for high conductors. I know that some trash will need to be dug to get to the coins, but a lot of this trash has came in at the copper/silver range and I'm talking about half of a 5 gallon bucket full of trash I've dug as of now. I don't know what it is about it...but it seems like I am digging a lot more trash that IDs as coins with the CTX than I ever did with the eTrac or Explorer. With the eTrac or Explorer, if it gave that silver tone and locked in, 9 times out of 10 it was something silver. On the CTX...well the junk bucket is getting used a lot. In some ways I feel like I'm back to using a beep/dig machine.

 

[sube]

Daniel your problem may not be ground noise at all I think it's similar to where I hunt. For # 1 put the 6 inch coil on that thing one thing I notice when you have a machine gun like hits in a area it is iron the 6 inch well give you the same depth as the stock coil in these areas .
What I have found is those targets that are not repeatable that you pickup using more sense than the machine calls for are tiny pieces of rust .I have some areas that have a million bottle caps that are almost rusted away little pieces of caps everywhere .Put that dime back in the ground and try the stock coil and see what depth you get with it set on auto plus 3 than put the 6 on and see what you get I also enable seawater mold which in my ground makes the machine run higher #s than without it enabled . the 6 should get that dime deeper than the stock coil because it well be able to run higher #s than the stock coil .
The stock coil well be picking up many more times the signals as the little 6 so the 6 will be doing a lot less work than the stock coil making it easier to separate targets and here them.
So what you need is a magnet and go dig those perfect false hits and see what you get 9 times out of 10 it will end up being a small rusted pieces of rust .As you use more and more sense you well here more and more of these signals . As you turn down your sense farther and farther you will see less of this.
So how do you run hotter in these situation what I do is use the 6 inch coil this will save your ears and give you a chance in this environment .Open screen iron set at 26 tone 100Hz Seawater on target trace and target trace pinpoint fast on combine on ferrous coin, the only 2 bins I care about are from 10 to 15 and 30 to 50 which I have set at 1000 Hz this makes it very simple to hear and than glance at the screen.
When I hit a target that hits in the 40 to41 range my wheat penny false I call it which usually ends up being a piece of rust or iron falsing is first x the target dose the depth change one way or the other if it's off a lot this is your first clue as to iron long items well depth read different than a round item the round item well be stable both ways or not but the depth will stay the same ,same as square items. To get rid of the square iron objects which hit and id as coins look at the ground where you visually see the spot on the ground dose it move from where you pinpoint or dose it change if it moves it's iron if it stays it's nonferrous . The square iron will false on a point of it giving you a high chirp and as you sweep the other way another point will high tone giving you another chirp which moves the pinpoint to a different location .
What I am looking for on target trace is a cursor that moves horizontally across the screen and stays on the 12 line not up and down this well tell you have a nonferrous hit
So to run hotter and get deeper you will have to check more falses listen to more junk and here more little rusted pieces of crap and x them away but the 6 will make this a lot more pleasant than the stock could even try to do .
You may think your not covering any ground but you are analyzing way more targets in this location than in others it just takes time because of all the signals
To give you a example where I hunt fairgrounds I found a area that had just loads of rusted caps when I sweep it would just turn the screen red all over the screen like a meteor shower looking at the screen was useless and I started hunting by sound alone . When I got a good high tone I x it and if it stayed were it was I dug it I ended up digging 16 mercury dimes
So my advice is do some testing with the coils and see what happens take your time .Also give your brain a rest every now and then :thumb .

 

[Daniel Tn]

I setup a program with your setting suggestions and can't wait to get back out and give it a shot. We just had 8 inches of devil's dandruff (snow) dumped on us here and this is the 3rd snow we've had in a weeks time. No chance to get out and play. BUT...I have been running various trash items under the coil with your settings and think it is going to work great. I keep a bucket on my porch and empty my trash from my finds pouch into it after each hunt. I had been digging a lot of trash that I thought might be coins. Using your tone suggestions and category resizing...I wouldn't have dug 3/4 of that trash by the audio it now gives.

 

[trojdor]

sube,

I think you've spent more time testing the various settings of the CTX than anyone else I know (including me)!
I've been curious to ask;
I notice you recommend turning on the saltwater mode...what/when have you found to be the advantage/effect of that?

thanks for your time,

mike

 

[sube]

trojdor
I started using seawater after Randy (digger) sent me a e- mail to try it out about 2 years ago .I tried running the ctx in the regular auto plus 3 mode and my #s were 21 to17 after the ctx settled down and found it self takes a couple of minutes of detecting before this happens , Than I switch to seawater enable after the ctx ran a couple minutes the #s would go up to 23 to 19 or 24 to 20 which gave me a higher sensitivity this is what the ctx wanted to run in without over driving the machine such as using more sensitivity than what the ctx deemed usable .
I started checking signals with it enabled and on the deeper coins when I would switch back to seawater not enabled the coins would sound weaker and some did not give any audio at all .
The way I decide to enable seawater is to see if your detector goes up in sensitivity this usually takes a few minutes for the #s to change , if I see a differences in #s that is when I enable seawater you should be in auto plus 3 for this test . When my #s go up then I will switch to manually .
Using the 6 inch coil my fave my # start out at 23 to 19 in auto plus 3 after I enable seawater they go to 26 to 21 this is in auto plus 3 so I switch to manually and push the machine all the way to 30 and the machine is a little sparky at that setting but not to bad if it gets unstable I will lower my #s to 28 and the ctx just smooths out doing the same with the stock coil my manual settings will in up being 24 to 26 without it being sparky .
As you can see the 6 inch runs hotter than the stock coil giving the same depth or more depth and is less sparky than the stock coil because it is seeing less ground witch makes it run more stable than the stock coil .
(what/when have you found to be the advantage/effect of that?)
It just goes deeper than when it's not enabled so check your #s like I said and see if it changes for you , my soil is moderate mineralization.
(Make sure you let your ctx run for a few minutes before you change to seawater and than a few minutes after the change to see if the #s change)
One other thing I will mention about target trace it has the same intensity as audio meaning if the audio is weak the target trace will be weak so if you can run more sensitivity the target trace will be clearer and same as audio .
But with pushing sensitivity higher than what the machine calls for you will get more falsing So you have to get better at calling falses and seeing the differences in falsing and a coin signal .
Chirps don't really interest me there usually falses What I'm looking for is a longer smoother signal that is coin like .
Do I get fooled you bet I do but when I dig that false I learn something every time and you should to .
A lot of people say it does not change there #s but I wonder if they ran the ctx in that setting long enough to see a change 2 minutes would be good . Then again it might just be there soil and mineralization involved.So only you can see how it works in your soil . sube

 

[trojdor]

sube,

Thanks for your response and explanation. I'll have to admit, of all the time I've spent fine-tuning my settings, and trying all the options, I've never even tried turning on seawater.
The thought had never occured to me...I do live in the highest land-locked state in the contiguous US...seawater is something I only see on videos!


mike