Fe Fe2 Mask Gold With Iron?

[Chase Goldman]

51 minutes ago, GB_Amateur said:

Since you are one of the most precise posters here (maybe more than I ), have I caught you in an ambiguous statement? 

Good point, Chuck.  Theoretically either, but since the update that introduced F2, I have no use for the FE filter, the answer is F2=0.

1 hour ago, Tiftaaft said:

So I'm torn... in one case... passing these signals up as iron would be nice (and especially on Chase's comments that he hasn't yet been surprised by an iron false being a coin - if I am reading his comment correctly - and even if they exist, they are rare). 

To clarify, I haven't been knowingly fooled by a pure iron signal being iron + a non-ferrous target with IB engaged.  The point of engaging IB is to mitigate falsing in the first place.  It is not foolproof, but when it works, it is dramatic.  I encountered a deep, large ferrous target last week that rang out with a nice pure high tone and 30ish target ID at 4 khz, 5 khz, 10 khz  and 15 khz single frequency (the quality of the signal degraded at higher frequencies).  When switching to Field 2 Multi with IB engaged, the target rang up as pure ferrous.

It is the iffy mixed ferrous/variable TID signals you gotta dig if IB is engaged.  It could be falsing ferrous that still got through the "filter" but it could also be mixed ferrous and non-ferrous targets in the hole or a mixed metal target.  Gotta check it out in that case.  HTH

[Tiftaaft]

Thanks for clarifying Chase.   ~Tim

[bklein]

Hi all. Ok I uploaded the video along with several others I made in the same day. Some EQ600 with 15”, some 11”, and some my CTX-3030.  A fair example of what I’m concerned about is this one: 

 

Sorry for the wrong camera (phone) orientation, road noise, and low audio.  The other videos show it seems coin groups reduce depth vs single coins with the Nox but not CTX, some masking with CTX depending on coil and coins orientations. I hunt beaches and don’t see many nails usually.  I avoid fire pit areas.  My main worry is just how targets detect in blacker sands.  I don’t have any at home but wonder if the same issues exist with it.  For you guys that hunt inland I can see you getting tired of digging falling iron - if a ring or coin is by itself out of the influence of something ferrous, the FE/F2 modes can help.  
Oh, the older EQ800 videos are some of my aggravations with the EQ800 I first had and eventually sold. Some of these issues may have been resolved with firmware upgrades or were due to my clueless use of the detector. One main thing you can see by these later videos is I need to set sensitivity down to almost quiet.  That, noise cancelling several times, and making sure ground balance is good (and FE/F2 are set to zero).  After this, bare coin depth detection seems maybe an inch or so better than the CTX sometimes.  The CTX though has the Smooth mode that gives you a much better chance of recognizing you’re over a target.  There actually is some bad EMI in this area, but both detectors seem to adjust for it over time.

[EL NINO77]

BKlein..your video is / long stored long for a non-ferrous target / a typical example, how the higher setting of Iron Bias has a negative effect ..

This setting of Iron Bias has the task of attenuating very short signals / targets / in a longer tone signal / signal from a long iron /

If you place the iron in a vertical position / at a height = short signal / between the targets, then it should not be a problem to detect it ...

In the EQ600 test you have Iron bias set to the value 2 / u EQ 800 = 6 / which is already a really high value of this setting.
 I consider the setting of Iron Bias F2 somewhere at the value F2 = 3 max.

For iron bias FE I consider it a safe limit FE = 0 ..

Another good example is also a test .. 2D surface separation type "Monte Performance Nailboard Test".

 Another very important feature of the Iron Bias setting, however, is also the effect on the "Repeated" detectability of very deep target signals ...

 Try to go through the coil 10 times over a very deep target .. and then repeat this test at a high setting Iron bias ... the results will be significantly different .

[midalake]

6 hours ago, bklein said:

Hi all. Ok I uploaded the video along with several others I made in the same day. Some EQ600 with 15”, some 11”, and some my CTX-3030.  A fair example of what I’m concerned about is this one: 

Whats your recovery speed again? 

[bklein]

El Nino77 - I’ve seen some videos of going over the target for a length of time to see it resolve it.  My thought is you’ll miss a ring and falseing sounds just like normal background trash noise as you are walking around swinging - I’m talking beach hunting though.
Midalake - it probably was 3 but not sure.   
These are just quick and dirty videos of things I’m trying, obviously not rehearsed...  I just added a couple more showing how coin grouping has depth suffer vs coins separated.  I didn’t associated this to FE/F2 - I need to go back and test to see if it is.

[midalake]

2 hours ago, bklein said:

Midalake - it probably was 3 but not sure.   
These are just quick and dirty videos of things I’m trying, obviously not rehearsed...  I just added a couple more showing how coin grouping has depth suffer vs coins separated.  I didn’t associated this to FE/F2 - I need to go back and test to see if it is.

Well these "gotcha" type moments, everything is important. Your coil speed relative to recovery and even how close you are to the targets. A few inches away??

I can tell you the odds of finding that set-up on the beach as you laid it down there is slim to none. 

Also difficult to hear really the audio response. 

 

[F350Platinum]

I was fiddling around with this today out in the field. Found this loud 16/17 target at 2", it was a huge iron ring about 5" diameter. I was in F2/0 at the time, switched to F2/2, and got a small iron grunt. Later I dug a 3/4" stainless steel nut at about 4". F2/2 and F2/0 did nothing. Solid 16! 😵

Maybe I just don't get it...🤔

[Raphis]

21 hours ago, EL NINO77 said:

Another very important feature of the Iron Bias setting, however, is also the effect on the "Repeated" detectability of very deep target signals ...

 Try to go through the coil 10 times over a very deep target .. and then repeat this test at a high setting Iron bias ... the results will be significantly different .

This!!  These statements aren’t talked about in the Nox manual, but I accidentally stumbled on this effect while fiddling with the new F2 IB when it became available.  I’m running F2-0 every hunt for ultra deep and partially masked/co-located targets passed over by many previous hunters (including myself) in heavy, non-ferrous trashy sites with moderate levels of deep iron, big and small, but I don’t detect in “blanket” ferrous sites that often.   At F2-0, I haven’t dug any more iron than I had dug with my Explorer SE for 9 years.  
 

If F2-0 IB is not considered “Off”, I wonder if there would be anything to gain if minelab offered a negative IB (i.e. F2 -1) ...possibly even better clarity/repeatability of ultra deep, whisper targets???

Also, at the sites I typically hunt, I’d rather hunt with the least amount of iron bias looking for ultra deeps, as opposed to try and lower my recover speed below 4.  In my typical ground I hunt, I don’t like the audio effect (more noisy/somewhat delayed) of signals when I try lowering recover speed below 4.  

[GB_Amateur]

12 hours ago, F350Platinum said:

I was fiddling around with this today out in the field. Found this loud 16/17 target at 2", it was a huge iron ring about 5" diameter. I was in F2/0 at the time, switched to F2/2, and got a small iron grunt. Later I dug a 3/4" stainless steel nut at about 4". F2/2 and F2/0 did nothing. Solid 16! 😵

Maybe I just don't get it...🤔

I don't get what you don't get.  😏  Are you surprised that the iron ring responded differently than the stainless nut? 

I view Iron Bias as trading off the two components of a signal -- effectively the ferromagnetic vs. the non-ferromagnetic.  Magnetite (the mineral in many black sands) is purely ferromagnetic.  Things like copper and its alloys are purely non-ferromagnetic.  Typical (non-stainless) steels give signals which are a combination of both components.  Iron bias adjustment trades off these two components by applying different weights to each.

There are many kinds of stainless steels and they have varying ferromagnetic strengths.  Some are effectively non-(ferro)magnetic.  I've never seen any that are as strongly ferromagnetic as pure iron and most types of non-stainless.  I think the most common SS is 304 (also called '18-8') and that one is slightly magnetic.  316 (more expensive and less corrosive so better near salt water) is completely non-ferromagnetic AFAIK.  Typically fasteners will be 304 designation since it's less expensive and does the job for most applications.  But I wouldn't expect 304 to see much if any change in signal by adjusting IB.

Having said all that, I don't really get Iron Bias (in a practical sense), period.   I was out yesterday, got an iffy (part ferrous, part non-ferrous) signal at F2=0 (in Park 1, Recovery Speed=4, custom 5 tones).  I switched to F2=9 and still got a combination of ferrous and non-ferrous response.  I dug down 8"-9" and recovered a very rusted 8-d common (modern circular cross-section) nail.