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Unmasking In Dense Aluminum With A Tesoro Detector


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I started a new thread on a subject that we were discussing in this thread.  In a post there, @kac said:

...When you get into can slaw and pull tabs you can easily just skip all that by cranking up the disc to the pull ring mark where class rings sit and most aluminum has dropped off and make an easy and quiet hunt for coppers and silvers.

This looks like what @dogodogwas saying he likes do when cherry-picking high conductor coins.  Sounds like you stil accept Zincolns.  Is that right?  Do you set the disc so that ringtabs are truly silent or on the hairy edge (giving ratty response)?  (kac continues:)

Hunting in the aluminum range the Tejon has the advantage of dual disc so you can work a tighter range but that can be just as tedious as hunting with a VDI machine and constantly checking numbers with the exception that as I mentioned before there is a pop to most aluminum.

Is the 'pop' dependent upon where you set the threshold?  I recall you (and maybe others as well) mentioning this previously.  Is this one feature that makes an analog detector superior to a digital (for that particular 'discrimination' technique -- I don't mean superior across the board)?  Is this something that you need to train your ear to pick up?

I think cut square tabs and nickels for me are too difficult to hear the difference and oddly their numbers are nearly identical on just about all my machines that have VDI screen.

I don't know what you mean by 'cut square tabs'.  Do you just mean modern racetrack shaped pulltabs broken off from the can?  So listenting for the 'pop' doesn't distinguish those from nickels?

If I'm expert at anything in metal detecting, it's aluminum drink can pulltabs.  I really like nickels and as you note, their dTID's (on detectors with digital Target ID readout) are in the same general range as pulltabs, sometimes with overlap.  Most of my experience is with the Minelab Equinox (to be specific I'm talking Park 1 or Field 1, 5 tones,  Recovery Speed = 4) and here is a breakout of the types of targets by dTID:

Nickels: (start with the 'wheat' and shift to the 'chaff'):  dTID sweetspot in the 12-13.  There can be differences depending upon such things as depth and amount of corrosion.  Shallow fresh drops are usually 13 while corroded ones tend towards 12.  Most of the time I get some 12's and some 13's.  Deep nickels (quieter on the volume scale and also more bars on the strength meter) can blip an 11 or 14, but still most of their dTID signals will be in the 12-13 band).  The signal strength is the key for me.  If I'm getting a rather weak nickel signal I'm not strict with the techniques below.  In my area pulltabs don't tend to be as deep as the deeper nickels so most of them give a pretty strong to very strong signal.

Rolled over beaver (only):  Have quite a bit of 11 along with 12 and a bit of 13.  In fact I can (most of the time) distingish these by going to Park 2, 50 tones, recovery speed=6 where they always give lots of 11.

Smallest (latest in series, so closer to 1975 vintage, particular the single piece ones as opposed to those with a rivet) ring+beavertail, extended:  mostly 12-13.  I end up digging all of these as trying to distinguish from nickels is too risky.

Modern punchout (near disk-like piece of thin aluminum that's part of the can lid and gets pushed into the can when opened):  almost completely in the 12-13.  These are pretty much impossible to distinguish from nickels, IMO.  Just dig 'em and cuss the idiot who went to all that trouble to remove them.

Bent over itself ring-only pull:  These are assymetric so probably give a 'tell' when picked up from different directions, but they tend to be strongly in the 12-13 sweetspot.

Modern racetrack pulltab:  Fortuantely these seem to be one of the easiest to distinguish with the Equinox as they give both 13 and 14 dTID's.  The 14 is in the long direction so if perfectly aligned you may get only 13 but you don't have to be much off that alignment to get the 14.

'Early' circular ring only (i.e. beavertail missing):  These are easily separated from nickels, somewhere in the 15-17 range but unless bent do not come close to the 12-13 sweetspot.  Of course these (and all others) are still a problem for jewelry detectorists and their symmetry (except for the rivet extension) make them sound really sweet, as if a nice fat gold finger ring).

Ring and beavertail (attached) but with tail folded over or even wrapped around the ring:  These tend to dTID lower than ring only, but still above the nickel sweetspot.  14-15 with maybe some 13 thrown in.

Some more unusual varieties (at least in my area) are the early 'squaretab' which rather than racetrack is closer to rectangle, and even kind of butterfly shaped sometime.  These dTID higher than nickels, and in fact a bit higher than the modern racetrack 'cousins', especially when not on-axis (meaning you're coil trajectory isn't solely along the narrow part).  Another less common are the small ring+beavertail (intact) which contain a rivet.  I'm not confident these are easily separted (dTID-wise) from nickels.  Finally, there are many varieties of ringtabs associated with other cans such as Pringle potato chip cans and some automotive fluid cans.  Those are larger and still further distance from nickels.  One last word of caution:  a fair amount has been written about Wartime Nickels ("silver nickels" which have no nickel content but rather quite a bit of silver and some manganese).  In my experience they signal with the same dTID's as standard nickels but some have reported their TID's going up even into the Zincoln zone.  In those cases, discriminating against pulltabs can lead to missing those.  I do think they are rare but maybe I've passed over some??

So, kac, after all that, how does your Tejon respond to these various pulltab types, and do you set your threshold so as to be able to ignore all of them?

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Cherry picking coppers and silvers is the easiest on just about any machine that has some sort of threshold discrimination or notch discrimination because they are above the ring pulls. This is even easier with a concentric coil when there is flat iron in the area that can ring high because flat iron stays lower on the scale with a concentric whereas a dd coil will put them up in the copper and silver range. So in the case of hunting in areas with flat iron with a dd coil, having iron audio option can help as you can hear the iron signal off the tip or tail of the coil (fringe of detection) and also your detecting the edge of the target. Larger iron like old bolts etc can be tricky and may not give an iron signal at all.

Zincolns can vary in break depending on how degraded they are and how deep they are so they can sit between the tab mark and the one above. I tend to accept them if they sond ok and keep 2nd discriminator at or just below the tab mark for much of my hunting. Old ground where small silvers could be such as half dimes and trimes the disc should be just above the mark between nickel and tab. This will also include flying eagles.

When I mean break on a target I mean set the discriminator so it breaks on that object with a broken signal and NOT whipe it out.

The older oval square tabs ring in at that line above nickel but if they get mutilated by a lawnmower and are folded or cut they will ring in lower at or near the nickel mark. The really beefy tabs will be heard well into the copper range. Square tabs in general like good chunks of can slaw will have a flat sound that takes a bit of practice to recognize as there is a slew of factors that can change the sound from depth to orientation or how dry the ground is. In general the audio is flat and has a small pop as you swing over the target almost like a subtle click and nickels are bit softer. Gold rings are very soft and can have a skip to them depending on orientation. That audio nuance is based off of the discrimination mode so in a typical target check I will hear a pop and flat tone i'll keep moving. If hear something different I will check range by pushing my trigger forward to tell if its in the copper+. Knowing what range the metal is in I can then use the pinpoint (all metal and listen to the size of the target and determine the depth (this is where the endless hours of digging junk can pay off) as this takes some good practice. Nickels at med depth will have a bit of a bark to them, deep cans have a long sound and can be heard even when the coil is lifted. Tabs have a flatter tone same with most can slaw. Object of different proportions can sound bit different depending on the angle you swing over them but often tricky to tell, this is where a VDI machine is handy as you get different numbers in different directions.

Open ring pulls sound like small rings and do have a softer tone than the squares but shouldn't be ignored on any machine because class rings are similar. So in a school yard or ball fields definately pay attention to them.

The pop isn't dependent on threshold. Threshold is only useable in all metal mode. Nothing fancy here just run it so I can just get a slight stable hum and use that for ground balancing.

Sensitivity on the Tejon and I believe most Tesoros adjusts the threshold bar so increasing it you pick up more ground feedback and decreasing it you drop the ground feedback. So in the field I typically raise my coil up and set my sensitivity so It is just quiet (no chatter) then as I hunt I may have to adjust as the ground may have bits of iron or coal that I want to drop out.

This is different than Gain which controls the overall power of the machine. One of the problems I run into with my Kruzer is it has the sensitivity cranked way up and can be really chatty in bad ground and dropping gain drops my depth. This is also true with the Apex and other machines.

 

 

 

 

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  Great amount of info guys, but your driving up the Tesoro marketplace with all this! Now how am I gonna find a good one at a reasonable price?!🤣👍👍

 

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1 hour ago, kac said:

The older oval square tabs ring in at that line above nickel but if they get mutilated by a lawnmower and are folded or cut they will ring in lower at or near the nickel mark.

Yes, I forgot about that.  I don't know what 'older' has to do with "oval square tabs" though.  (Would you explain?)  I wasn't aware there's a way to tell age if they are indeed oval (what I call 'racetrack' shape).  But, yes, broken modern racetrack tabs as well as ones bent over onto themselves dTID lower, typically enough nickel sounding to make me dig them.  Fortunately, like the pop-outs, they are pretty rare.  But some people seem to have nothing better to do with their time than remove pieces that were designed not to be removed, bend them, break them, and finally toss them on the ground.  'Idiots' is too nice of a word for them.

Thanks for your detailed response.  It confirms my previous thoughts that running an analog or analog-like detector is all about listening carefully to the multitude of sounds it makes.  I'm learning that backward, but hopefully I can still learn it.

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Guess the tabs I am referring to are not like the giant ones found on the energy drinks. They are a bit thinner and around here tend to be a few inches down so maybe 80's 90's?

Couple things with the analogs in particular the Tesoros is there is more audio changes not only to the target response by conductivity but also by depth and orientation so it takes a bit of learning curve. I noticed that digital machines still don't have those nuances and probably because they tend to run the gains higher to get better tid's at depth which I believe can flatten the audio.

I wish someone would make a VDI that gave you independant control with gain and sensitivity so you can really cut close to the ground phase and pick up those fringe targets and not get chattered to death.

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GB, Kac has pretty much summed it up with the Tesoros. His Tejon has multiple disc which is a great benefit to target ID. For the Much more simplified machine like the Compadre, Mojave or the silver umax, They still are quite efficient at target separation. Most people will tend to drift to the max depth and gain settings to help them find more coins, And in doing so they can punch past shallow targets and get a signal that they will sometimes bypass. Tesoros will still be fooled by big iron and aluminium or should I say still hit on. As Kac was eluding to, aluminum pull tabs square or round, anodized or not will cause some issues with your settings. Just look at some of the aluminum you dig with your 800, VDI's will be all over the range.  I have found that not all Tesoros are the same in regard to disc. and need to be air tested with trash, coins ect. that you have dug out of the ground. This will give you a real life test for you to set a disc pattern to break in a way that will be best for each site.  I mark with a sharpie the areas of disc I want to hunt with on the face of the machine. I also have a bag of misc. coins and trash I use at the site to help me fine tune the machine. (laugh all you want but it works). Kac is right when saying break your disc so you hear a crackle of your unwanted target. Tesoros are not super great on depth but I can tell you from experience that they dominate on disc and separation. THE most important thing to remember is depth is not king. Most of my silver finds are shallow in nail infested areas that the 800 masked out. The tones can take a long time to get the hang of, But lucky for you if you disc right it doesn't matter. Dig what it's hitting and you'll find yourself picking up some stuff that others are walking over. This being said it's not the greatest detector in the world, But another great tool in your bag that most people forgot about. No great mystery with the Tesoros just good old fashioned technology in it's simplistic form.

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1 hour ago, dogodog said:

I also have a bag of misc. coins and trash I use at the site to help me fine tune the machine. (laugh all you want but it works).

Who's laughing?  That's a common ploy of natural gold detectorists.  Thanks for the details of Tesoro operation.  I have some work to do to get up-to-speed with you analog detectorists.

 

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The Tejon with dual discriminators is more or less a luxury but not by any means necessary. Alternatively the Deeptech machines use 2 tones which make them very effective so instead of flicking a switch to hear a target range you can simply change your tone break and with the Vixta X they also added dual disc.

If I had the Vaquero I would first crank that sensitivity until I hear it chatter then back it off just until it is quiet. The sensitivity essentially changes the break point where ground mineralization and targets are audible nor not. In other words an area with coal fragments that can be not only sensed by the machine as ground mineralization but some of the bits can be heard as targets. Decreasing sensitivity you can essentially shift the bits that are audible into the mineral range whereby ground balancing takes over.

Next ground balance the machine. I used to run my Tejon hot but find if I keep an accurate ground balance the audio is better. This is where a nice low threshold as low as you can go and still hear it and have a steady tone. Fluttering is usually a good indication of EMI.

Key break points for disc for most hunting is just above iron for iron infested areas, just at the foil mark where there is can slaw, between the high 5 cent mark and tab mark for small silvers, coppers, etc. Flat iron breaks just below nickels with concentrics, much higher on a dd.

If you have some really good headphones that would be awesome. For years I had mediocre headphones on mine and once I tossed a pair of Garrett ms-2's it was a world of difference. I can see why people spend much bigger money on headphones. MS-2 work well and I like the volume adjust on them. They are also not expensive and I tend to break them when hunting in woods as I often get snagged up.

 

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  • 2 weeks later...

Reading the title of the thread and it not sure if it is correct for what we are babbling on about. Aluminum is a mid to high conductor and outside of using a concentric coil to combine or average the conductivity of 2 different targets your not really unmasking. DD coil you will need a small coil and a machine with good recovery speed to pick through the targets but anything below will be hidden.

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