CTX 3030 Target ID

[Jackalope]

While I like guessing if something is a nickel or pull-tab, penny or dime, gum wrapper or gold ring, yet in the end the CTX is really just used to differentiate between ferrous and non-ferrous targets, guessing isn't good enough. If it's a probable ferrous target - no dig, otherwise dig.

For me, the real benefit of the CTX (and E-Trac) screen layout (Fe vs. Co grid) is it better identifies ferrous than the standard single-line VLF phase display. No matter what I guess the TID, if it is perceived to be non-ferrous then it gets dug - that I suspect it is probably trash doesn't make it any less important, because it could be a ring (rings and trash live together), and I'm not leaving a ring in the ground.

So, for me I'm only interested in identifying ferrous (nails, bottle tops, hair pins, etc) with confidence - all other targets that aren't ferrous get dug. That's all I need to know - though guessing non-ferrous targets can be entertaining - though not relevant in the end.

Jackalope

 

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[bottlecap]

I know what you're saying Jackalope, I also like to try to dig any non-ferrous target. I guess what I am kind of wondering is if you can tell the difference between a bottle cap and a dime(this is just an example), for instance on my AT Pro I could tell the difference, there was a distinct double pop you would hear on the AT Pro when a bottle cap was under the coil, just wondering if any of you have noticed any nuances like this with the CTX, just trying to ease the learning curve a bit. Before I bought my AT Pro I read thread after thread about them and sure enough I learned quite a bit, and the first time I encountered a zinc penny I had a pretty good idea what it was before digging it because someone had described the difference in sound on here. Being not as many people have a CTX as AT Pro the threads are much more limited so rather than reading old threads I have to be fairly direct in my research.

 

[Jason in Enid]

What type of bottlecap? The common beer bottle tops that twist or pry off? I never dig those unless they are in the hole with a good target. The aluminum wine bottle screw caps? CTX loves those things, they come in like quarters.

 

[tcornel]

The pull tabs will ring 12-15 to 12-17. Beaver tails generally ring 12-22, 12/23 range. Nickels ring 12-10 to 12-13. Pretty reliable on telling the difference. On the ATP that wasn't the case.
Of course I still dig the pull tabs on the chance they are gold.

 

[bottlecap]

What type of bottlecap? The common beer bottle tops that twist or pry off? I never dig those unless they are in the hole with a good target. The aluminum wine bottle screw caps? CTX loves those things, they come in like quarters.

Sorry I was referring to beer bottle caps, twist off, those are most common in areas I hunt, I don't come across too many other types.

 

[ChampFerguson/TN]

Some sites you will dig a 5 gallon bucket full of Al trash before finding an appreciable amount of coins. Places like old schoolyards where there is a negligible chance of a gold ring(I don't consider silver rings since FBS eats silver alive). Literally, you will dig more than the value of any gold ring there before you dig such a ring if you try the 'dig all nonferrous' method.

Now the beach is an entirely different story. Most beaches are much higher value to trash ratios.
Every site has its own uniqueness and our challenge is to hunt it the best way to maximize the targets that we are after. There is no one way to do it.

 

[Jackalope]

I was on the beach in an area that was used by teens at night, so there were plenty of assorted beer bottle tops. I had pulled quite a few out as they were near the surface. I got another beer bottle top signal on the CTX and thought about skipping it, but I'm too paranoid, and sure enough when i pulled it out it was a silver ring (woman's). You just kind of look at it in dumbfound disbelief and then chuckle. But that's the way it goes ... so though I suspect the non-ferrous to be probable junk, it gets dug.

Same thing with clad pennies ... they are everywhere and it is tiring to pull them out, especially when they are deep. But one time after recovering dozens of these worthless puppies I was going to just skip that clad penny signal. And of course, that one turned out to be another ring - again I'm staring dumbfound that it wasn't what I imagined it to have been.

I really hate pennies, but unless I'm completely exhausted I dig them. I have found other jewelry since in the penny zone, so it can be a surprise. I like when I get a penny out of a 12" hole a passerby stops and asks what it was, expecting something worthwhile for all the effort and the deep hole, and I show them a corroded zinc penny, to which they say "oh, good for you". Yep, it is good for me.

 

[bottlecap]

Silver rings come up very similar to a copper penny, I Hanne experienced that, I've never been tricked by azinc though, every time I think it's a zinc it is.

 

[cudamark]

Sorry I was referring to beer bottle caps, twist off, those are most common in areas I hunt, I don't come across too many other types.

Just about all the bottle caps (not counting the foil wrapped ones) will read 01-22 to 01-25 I ignore those altogether as I've never got a good target with those readings. Now badly rusted caps can read all over the place, but, are usually a scratchy sound, but not always. There's no such thing as a 100% accurate target I.D. Some targets are going to mimic others. You just have to decide based on your experience with the machine, the location, depth reading, and sound as to dig or not.

 

[Jackalope]

A few years back I cataloged where targets appear on the E-Trac/CTX and made the idealized target ID display below. Gives an idea where good targets could generally fall. The point being there are good targets in many zones where garbage sits too.

 

[bottlecap]

Very cool chart. I think the basic idea with the CTX or any detector is dig according to where you are and possibly what time allows. If I am hunting a place with significant history I am digging everything, in a park pretty much everything but I will cherry pick if low on time, beach obviously every little thing, those are the three major places I hunt, beach, park, relic and how I approach them. My experience may be different than others though, I have found many more rings and jewelry on land than I have in the water, I found an 18k gold necklace pendant that was also part silver, it was a very weird tone, and even with the little bit of silver it fell down more in the garbage range, glad I dug it!

 

[jagchaser]

Im wondering if I messed up. I spent the weekend in Omaha hunting some old parks. I pulled a couple dozen copper pennies, an IHP, and a 36 quarter, but not one single wheat or nickel. After the first day, I got sick and tired of digging zinc, tabs, aluminum shards, and bottle caps of all kinds and so I tuned out everything below 12-33, and I passed everything between 37-41. Out west Ive never had a wheat ring up different than 12-44, but I wonder now if the numbers are a little lower there.

I will be going back in a month and will concentrate a little harder and dig those questionable numbers.

 

[Jason in Enid]

Im wondering if I messed up. I spent the weekend in Omaha hunting some old parks. I pulled a couple dozen copper pennies, an IHP, and a 36 quarter, but not one single wheat or nickel. After the first day, I got sick and tired of digging zinc, tabs, aluminum shards, and bottle caps of all kinds and so I tuned out everything below 12-33, and I passed everything between 37-41. Out west Ive never had a wheat ring up different than 12-44, but I wonder now if the numbers are a little lower there.

I will be going back in a month and will concentrate a little harder and dig those questionable numbers.

I routinely dig Wheats that read everywhere from CO-44 down to CO-35. Most come in around 39-40.

 

[ChampFerguson/TN]

fwiw, in my soils (dolomite/limestone derived), wheats show up at 40-41. A target covering those 2 #s is almost always a wheat.

 

[jagchaser]

I routinely dig Wheats that read everywhere from CO-44 down to CO-35. Most come in around 39-40.

Interesting! Im going to have to adjust my thinking when I get in the eastern part of the state apparently. Every 43-44 I did dig was a copper penny, but maybe those haven't had enough time to corrode like the wheats had. Out here its so dry I rarely see any corrosion.

 

[Jason in Enid]

Corrosion does seem to have a big influence in how much the CO numbers can shift. All of the wild numbered cents I dug were heavily corroded. For some reason, modern copper cents (1960 - 1982, not the zincolns) have the ability to read as a quarter under the right conditions.

One thing I noticed when I switched from the E-Trac to the CTX was that the CO numbers were more stable, even to max depth, BUT the CO numbers for each coin has a wider range. Even though a silver dime will read CO-45 when in good condition, the same coin being heavily worn down can read between CO 39 and CO 44. Its the main reason I tell all new users not to try to cherry pick silvers alone. If you aren't digging the copper cents, you will be missing a lot of silver.

 

[Jackalope]

It does make sense that corrosion or pitting of the surface of a coin would cause a lowered Co reading. If the FBS understanding is correct, the Co value is primarily the opposition resultant to the primary magnetic field by the secondary field in the coin's surface. The secondary field will be strongest in a high conductor and weakened by odd shaped targets or rough surfaces that do no permit eddy currents to flow freely. You could think of the secondary magnetic field that is created by those circulating free electrons on the coin's surface as a blocking force that neutralizes by having the opposite polarity, of the primary field of the detector. Think of it as a mini-force field that shifts the primary field off center of the coin. That shifting, to follow the analogy, causes an imbalance in an induction-balanced coil, which drives a current, which causes a signal on the non-ferrous target. The stronger the secondary field strength the more effective the primary is cancelled and the greater the shift and stronger the signal, all things being equal.

Interestingly, ferrous targets may have a weak eddy formation but their main driving force is that the electrons in the iron atoms can shift to match the polarity of the primary field, somewhat. As the primary A/C field switches polarity at the coil, the magnetic field drops to zero, which causes the magnetic domains in the ferrous target to return to their original orientation. That turning of the field to and away causes a secondary magnetic field in the ferrous target which does not oppose the primary field. It is the nature of ferrous targets to attract the primary field through it, unlike the non-ferrous target that repulses the field away. Bending into ferrous targets causes an imbalance in the I-B coil and drives the signal too.

But, ferrous targets that are slightly conductive find that the bending inward is greater, giving a ferrous signal but if you change the coil orientation a bit the conductive opposition causes bending away of the primary field - this back and forth battle will often cause a jumpy Fe value while the overall Co value will not move as much. If you lift the coil higher over a ferrous target, the primary field strength rapidly drops, the weak eddy currents in the rusted surface quickly die but the ferromagnetic nature of the target remains stronger. Thus, on raising the coil the Co values drop down and the Fe values rise higher, giving away the nature of the target (bottle top rather than coin).

I am surprised at times when a clear quarter coin target signal reveals to be a copper coin, which will register lower Co values when out of the ground. It may be that the soil conditions are better than average to create those eddy currents: perhaps wet soil and some conductive mineral salts help raise the Co value on a clean penny. Likely, those same salts and wet conditions will shortly ruin that same penny in the ground, and its Co value will drop a bit as eddy formation is hindered by corrosion. Certainly, when there are much ferrous minerals in the ground, the total volume under the coil of ferrous signal swamps the non-ferrous signal of the coin, and the Fe values will drop significantly, down to 29-30Fe. But if the coin is still in good shape, the Co value should stay in the coin neighborhood, depending upon depth of the coin and the angle of incidence of the magnetic field to the coin surface, with perpendicular field lines to the coin surface being ideal for keeping the Co values higher.

But it is still always disappointing to expect a shiny quarter and get a copper penny.

john