Ghost Signals

[Schmidt1989]

I'm a beginner, and I've been out with my Fisher F2 twice now for several hours. Once was on sand, the other was on soil that's mostly limestone (I'm in central texas, and it's mostly limestone). I got lots and lots of signals in both places, but whenever I'd dig, I couldn't find anything and scanning the area again would result in no signal. I've watched a lot of tutorials on the detector, so I feel like I have a basic understanding of proper scanning technique and the button functions on the detector itself including the different signal sounds/numbers/metal types. It was really frustrating to not find anything. I found nothing either time, not even a bottle cap or pull tab. Sometimes even pointing the detector towards the sky resulted in signals, so, what could I be doing wrong?

Thank you.

 

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[smokeythecat]

You are not necessarily doing wrong. I don't have a Fisher so can't give you much of an opinion on them. When I run into a problem I re-read the manual first. Make sure your settings are correct. I sometimes get "false" signals. Most of the time it's due to me whacking the loop (again) on weeds or corn stalks. At the beach a tiny piece of metal or a hot rock. Those hot rocks, mainly coal around here, just plain stink. I have had a few signals disappear temporarily, and then find them. Normally what happens is I've thrown it out of the hole farther than what I had expected, or it stuck to the shovel in muddy ground. If you're pointing to the air, and it goes off you could be getting electromagnetic interference. Make sure your connections are tight. If it keeps up, I'd also call the factory. Fisher stands behind their products.

 

[Joe-Dirt]

Try some air tests as well as what Smokey said to get a feel for it, set up some targets for yourself and see what happens from there.

 

[Kray Gelder]

Schmidt, welcome. I have had my F75 for nearly a year, and don't get out often enough. However, I have chased these gremlins myself. EMF interference is a nuisance in some areas, and I find searching in all metal mode, and listening for that good signal, and then seeing if the ID number is consistent. If the number is bouncing all over, move on. There are also mineral layers in the soil here, that give a good looking target, but disappear, or move when that layer is penetrated by digging. Look for a color change in the soil, or a band of color in the soil. You're going to get fooled now and then, and unfortunately, you're going to have to dig. I dug a quarter sized washer the other day, that was telling me I had 5 quarters in a rough circle about one foot in diameter. Thought I had a decent coin spill, but it was just a steel washer! When I dug it, the other targets disappeared. Go figure. Good luck.

 

[Loco-Digger]

I swung every F series fisher model except for the F5. Everyone of them would false if you are running the the machine too hot. Ruts in soil, walnuts, acorns, and hard weed stalks will cause falsing when you run too high of a sensitivity. To eliminate digging ghost targets, before I dig a target I double check it using an X pattern sweep. For instance if I detect a signal swinging my coil from North to South, I double check it by sweeping my coil over the target going from East to West. Hope this helps.

 

[Jim Hemmingway]

Hi Schmidt1989… your detector should not produce signals while the coil is raised in the air. Possible exceptions might include EMI generated from passing planes or traffic, or from industrial / residential electrical interference. Residential EMI is more pronounced during the summer months because air conditioners and pools are operating. It can make a real difference if searching residential parks. So ensure the coil connection is secure, and take smokeythecat’s excellent advice if this is an ongoing issue in areas that should be reasonably free of EMI sources.

In addition to the excellent comments above, let’s discuss ghost signals that are commonplace in the field, because normally there is a good explanation as to why such signals are produced. Let’s look at a few examples that most of us have experienced at one time or another.

A common scenario is a signal produced by disseminated / mineralized iron remaining
from iron junk that has rusted away in the ground. Rust is a form of maghemite, a powerful magnetic susceptible iron oxide that registers about mid-range on a typical ground balance scale. That is well below where your detector’s fixed ground balance is preset, and therefore it will produce such signals. When you dig and disturb the rust deposit, it will not likely be able to respond any further with an audio signal… hence we consider it to be a ghost signal.

A discriminated target occasionally signals in the dirt, but many will not respond once the
soil has been disturbed by digging, and / or the target has been brought to the surface. I don’t
know if this type of scenario applies to your detector because I’m not familiar with it. But I imagine it does. Keep in mind too that sometimes a small target falls deeper into the hole such that it can no longer be detected. A few more scoops will usually bring a target to the surface, but scan the hole with a pinpointer to be sure.

We occasionally see similar results using PI units while prospecting for Ontario silver. A
perfectly good signal is dug and voila… no signal anywhere. Usually associated with sponge or disseminated or even with weak leaf silver, once out of the dirt it will simply not respond to the PI electromagnetic field. In all cases to date, a VLF motion all-metal mode has quickly located such targets in the dirt pile. Although this doesn’t apply to your circumstances, you might as well know about it.

We sometimes encounter signals generated by ground anomalies that differ both in type and
strength of mineralizations from the general terrain. Examples include former campfire sites producing a positive hotrock effect even if actual rocks are not present, electrically conductive animal urination spots, or other relatively conductive spots usually related to the occurrence of various (fertilizer for example) mineral salts. Sometimes an abrupt physical change to the soil type such as a small clay deposit with differing moisture, electrical and magnetic characteristics can produce a signal. But digging disrupts the electrical continuity or magnetic fraction such that it can no longer produce a signal, and it becomes apparent there is no metal target. Thus we describe it as a ghost signal.

Hotrocks are a separate issue that I wouldn’t characterize as ghost signals. They are very real and identifiable signals produced by rocks. If you would like to learn more about the subject, click on the following link and scroll down to the hotrock section.

http://www.treasurenet.com/forums/c...-magnetic-susceptibility-february-2011-a.html

The bottom line is that your detector operates with a fixed ground balance and therefore your options are more limited. Learn to identify the hotrock types that occur in your area. Where hotrocks are plentiful such that they’re a real distraction, use sufficient discrimination to eliminate their signals.

Jim.

 

[against the wind]

Welcome to the forum from Port Allegheny, Pennsylvania.
Rewrap your coil cord tightly around your shaft and show us a picture.

 

[Ammoman]

All good advice. If turning down the sensitivity does not help, you might want to try switching out the coil with another. It is possible you may have a bad search coil or bad connection from the coil to the box.

 

[digger27]

Try this, Fisher swears there is no factory reset on this thing but many have done it after changing coils, when it starts to act wonky or at high EMI sites and it seems to calm it down and bring it back into line.
Nobody knows why but we have seen that it just does.
Turn it off then hit the power button again but keep your finger depressed on that power button as it powers up and for about 15 seconds after it comes to life.
You won't see any indications on the screen or any beeps indicating it did anything but as I said many have done it and noticed an improved difference in behavior after they did.

Also make sure your coil wire is not flipping around down near the coil and even though finger tight on the connection into the control box should be fine I always gave mine just a hair extra tweak with some pliers whenever I switched coils and that seemed to help too.

You could have a bad coil or just picked an area with a lot of EMI if it is jumping a ton with the coil in the air.
Try turning the sense down a bit...in decent soil the thing still gets decently deep even with the sense on just one or two bars.

Keep in mind you are brand new and don't know much...this will change as you get more experience and chasing ghost signals is normal at first.
I went after plenty when I got mine even though I had hundreds of hours swinging other detectors previously.
It just takes a little time to learn the nuances of any tool whether you are a total noob or a veteran but have patience...it won't take all that long.

I loved using my F2 and I was super successful with it because I took the time to learn it to as deep a level as I possibly could and it was fun and productive all along my three year journey with it.
Mine paid for itself more than 10 times over in the time I used it and found more silver, gold and coins plus a lot more than most believed possible from a starter unit.
It is a starter unit and it isn't...it still has the DNA from its more expensive higher end cousins running through it and thinks it is a much higher more advanced model compared to its price, or so I always believed.
There is only a few settings and a pretty simple language to it but I found there is another hidden and deeper language there also once you observe its behavior over targets and really learn to understand it well.

I have written a million words in posts all over the net about how I used mine and the things I noticed, discovered, observed and learned that helped me, (and many others), get the best out of this thing.

Google...F2 review.. Final impressions below,.....
This is a simple review thread I started but grew into one of the longest most views threads on the net and has sold a ton of F2's for Fisher and helped many move along that initial learning curve much faster.
Tons of info and advice about using this thing in there from myself and others that were lucky enough to swing this thing.
My whole journey from my first day, all I learned as I learned it.
Take the time to read it...it might help.