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Digging the Deep Coins - "Flying Blind"



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Following is a little article I've written about digging the deeper coins;  I've given special consideration to using an analog, one-tone, audio-only detector.  In other words, no visual display, no tone distinction.  You have a panel with a bunch of knobs that controls everything. 

I consider this one of the enjoyable challenges of metal detecting.  It is pure sport, the exact opposite of what a lot of people would do if they could (i.e., buy something with a video monitor that shows a picture of exactly what's in the ground).


A Realization

Years ago when I had my first detector (a Coinmaster), I thought I was hot stuff with my target ID meter.  A needle would point to the word corresponding to what the buried object [probably] was.  This was the pinnacle of metal detector technology, circa 1986.    No pulltabs for me, no sir.   OK, maybe a few pulltabs.

Then one day I met up with some other hobbyists who had Fisher and Garrett metal detectors.  They didn't have target meters, just a bunch of knobs... yet they were finding coins.  In fact, they were finding more coins than I was!  How could this be?  They had no VDI, no depth indicator, no nothing. 

It didn't take me long to realize something I've seen reinforced many times over the years:  a purely knob-type machine in the hands of a pro will often beat the latest target ID technology in the hands of a neophyte. 

I also realized that a lot of old hands at this sport don't like to become too reliant on visual ID meters.  As experience slowly taught me, it's because the meters sometimes aren't accurate.  It isn't intentional;  it happens usually because the coin is deeper than the meter can reliably interpret.  Meters can also give false readings on objects that happen to have the same conductivity as the desired target.  Certain types of junk can fool the best of them sometimes.


Pick Your Favorite Site

Now that we have some background, let's go on a trip to find some deeply-buried coins.



This is the kind of machine I prefer for this sort of detecting.



We walk into the old park and pick a spot (after, of course, we make sure it's OK that we detect here).  Forget the wide sweeps and fast ground coverage that the beginners like to use.  It's time to slow down and stay in one area- preferably an area that has produced coins before.   Sweep width is going to be narrow, maybe two feet at first, narrowing even more when you get a blip.  Go back and forth ten or twenty times over that blip.  See how it responds when you vary the sweep speed.   Is it smooth?  Repeatable?  Sweep the target from another angle, maybe just 30 degrees to the previous axis.  Walk around the target and keep sweeping it from different angles.  Does the signal disappear?  Does it appear to move a few inches away when swept from another angle?

That smooth, repeatable sound we're getting:  what is it?  A coin, a pulltab, a piece of foil, or a nail?  Here we're not relying on LCD screens or multi-tone audio.  With a machine like the Tejon, the Vaquero, the Silver uMax, etc., we rely on the discrimination and the quality of the mono-tone (i.e., broken or smooth, hard-edged or soft, etc.).   If we're after the deep treasures, we also have to rely on stubborn persistence, digging many targets that others would leave behind because they didn't look and sound "just right" on the latest piece of equipment.  Guess what?  Some of these overlooked signals are coins!  The other detectorists thought they found it all.  I am always thankful when others are in a hurry to move on to other sites.

Don't worry about junk.   You're going to dig some of it;  that's all there is to it.  Long-buried square nails will often fool the discrimination- on any machine.  While there are usually differences in the signal, these can be extremely slight and will fool beginners often.  In practical terms, that means you will dig many nails.  In the typical "hunted out" area, there could be double handfuls of nails for every coin you find.  Perhaps you could hit a streak and get as many coins as nails.  Nobody can know what the day will bring.

We're after the deep coins, so we're listening for signals that are quiet and narrow.  Take your time!  Move just one inch off center and the signal isn't there.  The way to tackle this ground is to focus mentally on a small sub-area of the small area you've picked out to hunt.  Don't let your eyes wander all over the place-- look at a 1 foot square piece of ground at a time... really search it. 

It's all about the narrow, faint signals. 

Before we discuss the three types of coin signals, let's talk about the kind of signal that's probably not a coin.  Suppose you swing the coil two feet, and the beep seems to last for half that distance.  Let's suppose you pick the coil up six inches from the ground and still get a loud signal.  That is not going to be a coin.  With practice it becomes easy to tell when you're dealing with an oversized object.  It could be a beer can, a piece of sheet metal, a strap hinge, or almost anything.    Crushed beer cans at shallow depths will act "round" but give a loud signal even when the coil is held off the ground several inches.  If you're lucky enough to find a silver dollar and it happens to be shallow, you may think you're dealing with such an object.   For this reason, some coin hunters dig signals even after they say "yep, probably a beer can"... once in a great while these loud signals turn out to be something very interesting.  Recently I got one of these loud signals and decided to dig it "just to get it out of the way".  It turned out to be an old axe head, a relic definitely worth keeping.

Now let's talk about the signals that might be coins.

The "textbook" coin signal is "round".  What I mean is that the signal will have the same characteristics no matter what angle you choose to scan it.  As you walk around the target while swinging the coil back and forth, the sound will still be smooth and repeatable from all angles.   If it beeps for half an inch one way, the "round" signal will also beep for half an inch every other way.  In other words, it "sounds" the same size no matter what angle you choose to scan it.  This "classic" coin signal also has well-defined edges (on most detectors);  it begins and ends at obvious points rather than fluttering, hesitating, or fading in and out gradually.   However, it is not "clipped" unless you're at the hairiest edge of detection depth.

Dig every one of these "textbook" signals, especially if your discriminator knob is set at "pulltab" and they're still good.

Here's a hint.  Just because this signal is solid and smooth doesn't mean you won't miss it.  You could hunt a ten foot by ten foot area several days in a row and still find you've missed a few.  The signal is solid, and when you hear it you should recognize it as good, but you might not hear it!  If the coin is 6 inches deep, the active portion of your coil's field is only a couple inches in diameter.  You could swing right by it and not get that "hot spot" right on top of the coin.

Remember, some nails and other junk can occasionally mimic the classic "coin" signal.  Rusty washers are notorious for this.  Don't let this discourage you.  After enough practice, when you get a signal that makes you say "that HAS to be a coin", you will be right more often than not.


Some Goodies Don't Sound That Way

Next is the "iffy" coin signal.  I don't know who coined the phrase "iffy signal", but it's in wide use among detector hobbyists now.  Exactly how the "iffy" ones sound (as opposed to the good ones) will vary between detector brands and models, but you will learn them by experience.  The iffy signal may not sound quite like a coin.  However, it should be repeatable along at least one axis.  You may scan it east-west and it sounds good;  approach it from north-south and it may disappear or break up.  Most of the ones that sound great along one axis but disappear altogether from another are nails;  however,  coins can and do sound this way sometimes as well.

Beyond this is the "very iffy" signal.  Not only isn't it consistently good from all angles of approach, but it also doesn't really sound that solid along any axis.  It doesn't sound like a winner no matter how you scan it.   This one is probably junk, but there is a chance it may be a coin... perhaps on edge or next to a nail.  A nearby zone of heavy mineralization may be distorting the field.  It could be any number of reasons.  

If you have found any coins at all in an area, dig ALL these signals in the immediate vicinity.  You may be pleasantly surprised.  Recently I got one of these highly "iffy" signals and decided to pursue it.  The previous dozen or so of this kind had all been nails, but I was running out of daylight and really hoping I'd finally hit a coin.  Well, that's what it was.  It turned out to be a 1912 Barber dime at a depth of 9 inches.  Badly worn, it's maybe a $2 coin on a good day... but finding a Barber coin, any Barber coin at all in the ground, is one of the thrills of this pastime.  

Finding a Barber coin at 9" deep, especially in a hunted-out area, is an experience money cannot buy.    $600 can buy you a machine that can detect the dime at 9", but it cannot buy you the skill and patience that guarantees you put your coil on that exact spot and decide to dig it.   In this way it's similar to golf, billiards, fishing, and a number of other sports- one can easily buy all the right gear but not use it to its fullest potential.

After you cut the soil plug and fold it away from the hole, scan the hole again.  Sometimes the signal goes from questionable to very solid just from taking this couple inches of dirt out of the way.  This is a highly encouraging sign.   Every time this happens, I tell myself "this could be a coin!"  Well, often it's still just a nail-- two or three inches off to the side of the hole, no less-- but at least you know you're not chasing a phantom when this happens.  On the other hand, if the signal goes from highly iffy to nonexistent after folding back the plug, chances are it's a small bit of foil or other trash that's very shallow.  You'd do well to extract it from the plug and get it out of the way so you don't re-detect it at some later point.  This kind of work can help un-mask coins in the future, as well.



All of the rusty iron pictured at left gave very solid signals that didn't discriminate out.  As soon as the earth was disturbed and the rust halo broken, the signal deteriorated. 

A big chunk of iron at 10" deep can sound just like a coin at 6" deep.    The only way to tell is to dig it.

(I should add that with experience, you will dig less iron... there is often something different about the tone, but it's easy to miss.)



Weird Stuff

While we're on the subject of signals that change when the hole is dug, I'd like to talk about something odd that I've noticed. 

Silver is the most highly-conductive metal on the discrimination scale.  It should not discriminate out, right?  Certain hobbyists will claim that silver does not form a "halo" in the soil.  Explain the following situation, then: 

You get a broken signal;  You fold back the soil plug and the signal becomes smoother;  you dig a bunch of soil out of the hole, the signal disappears;  then you scan the soil you've piled up next to the hole-- no signal there either.  Wait, what??   You scan the pile again and notice there is in fact a faint, broken "junk" signal you missed the first time.  It was probably a nail, and it's acting this way because you broke the rust halo, right?

You turn the detector to All Metal mode and get a loud, repeatable signal. 

This time it's not a nail, though.  When you finally pick out the culprit, it turns out to be a silver dime!

I've had this happen at least a dozen times.

If we're to assume silver coins produce no halo in the soil (actually, they do), then I can't imagine why this happens.  Ground balance has a limited effect on this strange occurrence, but fiddling with the settings suggests it isn't the main factor.  Why should the discriminator circuits reject a silver dime that's only a couple inches from the coil and not covered by any intervening dirt or minerals?  Nobody has explained this satisfactorily.


How To Get The Most Depth

A good metal detector for deep coins should have three features:

- Adjustable Sensitivity

- Manual Ground Balance, rather than factory-preset.

- Manual Threshold adjustment

Given these controls, there are three different ways to get more depth:

1.)  Turn up the Sensitivity.  If you turn it too high, you'll get false signals.  There will be some optimal setting for the particular conditions you're using... you just have to find it.  A really experienced operator can learn to ignore most of the false signals.  On Tesoro machines, crank the Sens to the red zone and you'll get quite a performance boost.

2.)  Adjust the Ground Balance to be neutral or slightly negative.  If your GB is positive, you'll overlook a lot of stuff.  However, a lot of beginners are told to set their GB slightly positive so they don't get a lot of false signals. What works best will depend on your soil conditions.  A slightly negative ground balance means the threshold will get quieter as the coil is lowered to the ground.  If it does not change at all, that's a neutral ground balance, and if it gets louder as you lower the coil, that's a positive ground balance. 

3.)  Supertune the machine.  Do this by turning the Threshold all the way up (clockwise) in Discriminate mode.  You can't use All Metal mode while a detector is supertuned, but the Disc mode will now hit much louder on deeply-buried coins and other objects.  Faint to moderate signals will sound like they're near the surface.  You might not be prepared for the amount of digging required to uncover that "shallow-sounding"  beep you just heard...


Which Detector For Deep Coins?

If you're after the deep coins and you have the patience, I think analog is still the way to go.  I say that having put in a lot of time with digital detectors, including Minelab, White's, Teknetics, Fisher, BH, etc.   To be sure, you can meticulously hunt deep coins with a Teknetics T2, a Minelab E-TRAC, or a Fisher F75.  Nothin' wrong with that at all, but this article is primarily about the "old school" types of machines.
 
Master the techniques, and you may become one of those people who can go into sites that have been pounded with Explorers and F75's and still find coins with your beep-dig machine.  If you listen to some of the guys with $1500 detectors, this shouldn't even be possible.  

Here are four current-production detectors I'd choose without any hesitation.

Tesoro Tejon  (currently about $595 here).

Tesoro Vaquero  (currently about $450 here.)  The next best thing to a Tejon.

Fisher 1270X (goes for about $595 here.)   (Note:  This was current when I first wrote this article, but it has recently been discontinued.  Fisher decided to go in an all-digital direction, leaving only Tesoro to keep making quality machines in this tradition.)

Tesoro Outlaw (currently about $552 with the three-coil bundle).    Go for the bundle... you'll eventually want those other two coils anyway.  The Vaquero will go somewhat deeper, but a lot depends on how you set the ground balance.  

If you're on a smaller budget, get the Tesoro Cibola (about $362 here) or the Tesoro Silver uMax (about $258 here).  Either of these can reach pretty deep, with the Cibola being quite a high-performance machine for the money.  The Silver is no slouch either (full review here).  As far as I'm concerned, either of them will outperform any of the fancy "digital" detectors in their respective price ranges.   However, just remember that if you want maximum depth, you'll need a machine that has manual ground balance and manual threshold adjustments.  That's why I'd go for at least a Vaquero or an Outlaw.  When you go with preset machines, you WILL lose considerable depth under certain conditions, and you won't be able to adjust.

Want surprising depth for not much more than you'd pay for a toy?  Get the Tesoro Compadre with the 8" coil.  Price:  about $160.  Here again we're talking about a preset machine, but look at the price.  The Compadre also lacks the ability to change coils, but you can't beat it for the money.  (Don't get the one with 5.75 coil if you're after maximum depth.  It's ideal for high-trash areas, though.)

With a Silver uMax I went through a place "cleaned out" by an experienced BH user.  I found some really cool stuff at depths he couldn't seem to reach.  I had to use the techniques discussed in this article, which means I moved slowly.   You could probably pull off some brag-worthy feats with a Compadre, too, as long as you get the one with the 8" coil. 


Putting It All Together

In this article, I've written about what I think is the most valuable set of techniques for finding older coins.  Some people will say success is all about research.  They are correct in a sense, but... even if you research the stuffing out of a place, you won't find that deep coin unless you put your coil over it and listen carefully. Even sites that have never been hunted may lack any shallow coins;  it depends on the ground conditions, erosion, leaf deposition, and a number of factors.  Recently I hunted a site where I knew the only coins had been dropped in the late 1970's.  They were already 4 to 5 inches deep.

If you don't dig that "iffy" signal, you will be leaving something in the ground that might be a deep coin.  It's probably junk, but you'll never know until you unearth it.  Consider Schroedinger's Cat.  If you don't dig the signal, then as far as anyone is concerned, the target remains a superposition of all possible metal objects that could produce that sound. You have to collapse the probability states and make it be something definite.  (Ok, so perhaps it's not technically a Schroedinger's Cat situation, but it works for me.)
 
You have to dig it to know what it is.


Take your time, move slowly, have patience, and you will eventually find cool stuff.  Don't get frustrated if you feel like your fast-moving friends are cleaning up.  Anyone can pendulum-swing a Bounty Hunter through a site and find the easy stuff in the 1- to 5-inch depth range.  Anyone with enough money can get an E-TRAC and sweep through a site for the obvious "high tones".   Sure you can get one of these machines with a giant steering-wheel of a coil and windshield-wiper you way across a field to cherry-pick the easy coins... but that's not really a challenge.  Digging the deep coins that others have missed... the deep coins that might be next to a bunch of nails... now that's a challenge.

One last thing, for beginners who may not know already: 

Digging every signal in a small area can turn a place into a mess.  Don't try to "clean out" an area of all its metal in one day!!!  After you dig a few holes in one general area (and fill them back in), give it a rest and let the grass recuperate.   Turning someone's land into a muddy mess is not going to get you invited back, and it may damage the hobby in the long run.  If you are working a spot and really want to "grid" it and dig every signal, stretch it out over a span of months if possible.  Hunting the deep coins is a long-term proposition.  Nobody goes into a spot and cleans out all the deep coins in one day- it's just not possible nor even a good idea to try.  Take your time. Enjoy each swing of the coil.  Learn from it. 

Be sure to FILL ALL HOLES you dig, and make sure you tamp the grass plugs down firmly.  Wild animals often come along and tear out plugs that aren't tamped down securely.  Skunks, racoons, dogs, and even squirrels will dig up plugs in search of things to eat.   

Filling holes back in without leaving obvious traces you've been there is THE most important part of the metal detecting hobby.  Without a doubt.  If you can't do this right, you'll ruin the future of the hobby for yourself as well as for everyone else.  Practice in your own back yard until you can cut a grass plug, extract the target, fill the hole, and put the plug back so nobody will even know you were digging there.  Avoid digging plugs in very dry weather.   Also, don't try digging when the ground is mush.   It should be damp but not soaking wet.

When you dig a plug, don't sever all the grass roots- try to leave the plug attached to the rest of the grass along one edge, like a hinge.    If you know the coin is shallow, instead of digging a plug, make a small incision with a screwdriver and pry the coin up from the ground.   Practice these techniques before digging on any property you don't own.  And above all, ask permission before you go on someone else's land.


Let's Keep 'er Goin'

The article you've just read contains a lot of hard-learned information.  (It's been more useful to me than what I've found in most books.)  If you found it helpful, there are two ways you can help me out in return.... donate through the Paypal link (below), or use any of the links on this page to buy your metal detectors (or anything else, from hair products to socks.)   Help me keep bringing you the best in metal detector articles & reviews!



Your kind support helps me keep this site going and adding free content.  Thanks!!







Thanks again for visiting!

-CHRIS


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Here are some good choices for the kind of detecting I talked about in this article.  Help me out by purchasing your detector through these links...


Tejon




Vaquero









Nautilus DMC IIBa w/ 10" coil




Fisher 1270








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