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F2 Iron Bias Non Ferrous Targets


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Thanks for posting this Jeff.  I have a site I’ve been hunting on Sundays for a couple of months now.  I always start out near the parking area and have done well.  I’ve mostly been using park one in 5 tones set up to my liking.  Iron bias on f2 usually set from 4-6, but never 0.  Recovery speed almost always 5 or 6.  This area used to have mill houses that were torn down back in the late sixties.  Needless to say there’s lots and lots of iron and quite a few pieces of coke from the coal burning furnaces that were used back then. There’s even a lot of surface coal from when the houses were razed.  It reminds me of when I grew up in the coal country of Southwestern PA.  But this site is in Western NC.  Anyways a couple of weeks ago I decided to try F2 set at zero.  I started out from the parking lot as I normally do just swinging randomly working my way to a new area as I’ve hit this area by the parking lot three or four times already and wasn’t getting much.  This time however with f2 at zero I immediately hit a wheatie.  Then another and another.  Then a few more.   Then I get a solid 32-34 and out comes a silver Washington quarter!   After a while I went back to the car to take my sweatshirt off since it was getting hot.  There’s this 10’ wide strip of grass between the car and a service road.  I’ve hit this area before with both the 11” and the six inch coil.  I scored two silver dimes with the six incher and covered the area really well or so I thought.  This day I had the 11” coil on and low and behold I get a nice solid 28-30 and out pops a silver rosie, but in the same hole before I found the dime was a pretty big (3”) rusty nail and then a rusty steel washer about the size of a quarter which was what I thought for sure was giving me the good signal.  After I pulled it out I rescanned the hole and still got the 28-30 so back in with pinpointer and there’s the silver rosie!   
 

I can see missing one wheat or two, but I think I got 6 or 7 wheats and the silver GW out of that one area that I had pounded previously.  Then the silver rosie out of the other tiny area that I had pounded with both the 6” and the 11” before.  

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Thanks NCtoad.
From some of the responses so far it does appear that using too much F2 iron bias can result in missed deeper non-ferrous coin sized targets from some of your experiences. For me, I don’t think too much iron bias has an effect on depth of non-ferrous coin sized targets. I do think using too much F2 can seriously skew towards iron how a deeper non-ferrous target audibly responds which for me is definitely an issue. There is plenty of natural and human made deeper iron where I often detect. I trust the Equinox so much that when a target sounds like iron I may move on to the next target. After today I will only do that if I have F2 on zero.  

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There are two things that this thread drives home, at least for me.  The first is that we all have our preferences, more specifically targets we want to make sure not to miss and those that we don't mind if we (occasionally?) miss.  We all hunt in different soils with different histories.

The second point is that the ML Equinox has so many 'knobs to turn' that it's really many different detectors in one package.  So each of us can set it to cater to his/her preferences, soil conditions, drop history,....  (The list is much longer but the highlighted apply most directly to this thread.)

 

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1 hour ago, Jeff McClendon said:

. I trust the Equinox so much that when a target sounds like iron I may move on to the next target. After today I will only do that if I have F2 on zero.  

That is where having the custom profile button on the 800 comes in handy.  For Beach hunting I have been experimenting with audio and frequency settings that best enable irregularly shaped aluminum targets  (e.g., can slaw, crushed cans, and broken/bent pull tabs) to be revealed through hollow-sounding tonal "distortion" and similar to using the Deus in full tones.  What I discovered was that this was best accomplished using single vice multi frequency.  The drawback is that by going to single frequency, you lose iron bias which really helps to ID crowncaps. So there was no way to set up the Nox to give me the best of both worlds.  The solution was to search in Beach mode with IB at my default setting which enabled bypassing crown caps easily but to use a single frequency setup stored in the custom profile slot that could be called up at the touch of a button to interrogate iffy mid conductive targets to determine whether it was likely aluminum junk or a probable ring or nickel.

A similar setup could be used to search with non-zero IB settings and then interrogate ferrous signals with a custom profile program with MF and zero IB or simply a single frequency variant of your main search program.

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54 minutes ago, midalake said:

Hi Jeff

When you say you hunted in Zero Discrimination do you mean horseshoe mode? 

Yes.

Dave, I have no idea how any of what has been said here would apply to the saltwater beaches you hunt in Mexico.

Personally, I don’t mind digging steel crown bottle caps. 

I have hunted east coast USA beaches where a nickel stays in the correct numerical and tone ID all the way down to a foot deep and the same with other non-ferrous targets with FE or F2=0 or 1 using Beach 1 or 2 in 5 tones. At some San Diego area beaches I have hunted, everything sounds like iron after about 6” depth no matter what FE or F2 is set on. I usually just hunt there in 2 tones and dig it all.

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As someone who hunts in a part of the world where in a park or beach situation I'm about as likely to find a gold ring as I am a nail or bit of iron I couldn't care less about iron bias.  I set it to F2 0 and I'm all good.

Bottle tops are my only problem but they're not all that much of a problem either with not all that many of them to cause issues, the most common sort are alloy off some types of carbonated drinks which are going to be an issue to anyone. 

I've soaked up the information in this thread just in case I need it someday though if I hunt in a more populated area of litterbugs.  In saying that, I bet Metal detector users are the least likely people in the World to throw their bottle caps and pull tabs on the ground after having a drink 🙂

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1 hour ago, midalake said:

Hi Jeff

When you say you hunted in Zero Discrimination do you mean horseshoe mode? 

OK. I have thoughts.

So I have done some testing of F2, but still hunt in FE.  After a whole year of testing FE6 and FE4 there was no difference in targets that were dug. 

I am going to guess that there may be different reactions in different modes do to frequency weighting?  I don't know this for sure, but is plausible.  

So when hunting in beach 2, when it comes to very deep targets I have learned to identify them as ferrous and non ferrous by the telltale fact that a ferrous target [at depth]  will double ring/ and or breakdown as you work around the target.

So I am convinced that things like Black Sand and Salt Water have a distinct effect on the Equinox ability to show a correct VDI number at depth.  Throw in a little EMI, it is even worse. 

I am working in FE because I found F2 does not double ring on ferrous as crisp. 

To see how well this works, when I had deep targets I thought were nonferrous I then switched the Equinox over to Discrimination. All of these fringe deep nonferrous  Never even registered in discrimination.  Not even a little beep or tick of a sound. 

Personally I have not made a connection to higher IB numbers masking targets.  I fully plan to work on this more when back on the machine. 

 

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Dave, at least from my testing and experience, the F2 version of Equinox iron bias is much more aggressive than the original Fe version. Also, similar to your situation, on beaches where there is plenty of black sand, using any iron bias setting doesn’t make much difference on non-ferrous targets since they start to all sound like iron past a certain beach specific depth.  That double beeping on iron targets, especially nails, is a very common telltale on most VLF and PI gold nugget detectors too. It is not foolproof but for shallower iron it can usually be trusted. On deep stuff………..taking a chance.

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10 hours ago, Jeff McClendon said:

It is not foolproof but for shallower iron it can usually be trusted. On deep stuff………..taking a chance.

For some reason on wet sand I am getting this done to incredible depths and the faintest of audio. The reliability factor has been high. Also can run 23-24 sensitivity most days. 

I also have been running the threshold on a position or two. While this does not create a true audible threshold, it seems to enhance deep targets. 

Jeff, I think you said you were restricting the lower iron bin. Maybe since deep targets both ferrous and nonferrous do not come out of this bin, restricting it might have consequences with hearing the right sounds? I don't restrict the bottom bin. 

Can anyone remind me what FE6 would be in F2 settings? 

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