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I don't know if I'm right on this but I've found my Teknetics T2 to be a good guide to mineralisation at an area, I use its Fe3O4 meter as a guide.

 Would I be right in using that as a guide?

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On 8/6/2018 at 12:52 PM, phrunt said:

I don't know if I'm right on this but I've found my Teknetics T2 to be a good guide to mineralisation at an area, I use its Fe3O4 meter as a guide.

 Would I be right in using that as a guide?

Well, all I can say is other than putting some kind of number out here for comparison purposes I have never found an Fe3O4 meter to make any difference in how I tune and use a detector. I listen to how my detector reads the ground and tune appropriately. I did this for decades before there was such a thing as a Fe3O4 meter and when they showed up my habits did not change. I find them extraneous to the way I work and basically don’t pay attention to them. I would rather the Gold Bug Pro or G2 show a large target id while in all metal mode and lose the little “speedometer arc”.

The Fe3O4 meter started in the White’s GMT (a Dave Johnson design), and is now featured in many Fisher and Teknetics models that Dave had a hand in like the T2, F75, Gold Bug Pro, G2, etc. Nokta and Makro have similar meters on many models, as do others.

The following link goes into the meter in great detail....

 GB Numbers = Mineralization?

This function has been promoted as a “follow the black sand” feature but I personally believe the usefulness for tracing black sands is minimal. The effect is so limited to surface readings I find my eyeballs to be the better tool for deciding where to pan for gold.

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On 8/6/2018 at 3:52 PM, phrunt said:

I don't know if I'm right on this but I've found my Teknetics T2 to be a good guide to mineralisation at an area, I use its Fe3O4 meter as a guide.

 Would I be right in using that as a guide?

Hi Simon… you are quite right that the Fe3O4 feature is useful to evaluate soil ferromagnetic mineralization. Use the Fe3O4 readout in conjunction with the GB readout for a more complete evaluation of what general type and strength of soil minerals exist beneath the coil.

I also agree with Steve insofar as the Fe3O4 readout has never influenced my ground balance procedure either. But it does help newcomers to the hobby, some otherwise may never grasp the fundamentals of evaluating ground mineral effects that experienced hobbyists have employed for decades prior to the introduction of the Fe3O4 (and GB) readouts.  

These readouts can offer newcomers some confidence in selecting suitable coils to search tougher mineralizations. Such ferromagnetics are more easily handled by using DD coils and smaller coils, or both. However as an aside, I see little or no difference between concentrics vs DD with my smaller 6” elliptical coil configurations. The smaller coils also permit using higher sensitivity / gain adjustments compared to larger coils when detecting over tougher ground minerals.

Steve’s example to illustrate ground effects on ground balance adjustment is excellent. You will find that as the strength of ferromagnetics increases, there will be less latitude available in coil height movement in order to keep the coil ground-balanced when compared to light / moderate ferromagnetic strength soils. You will observe that the coil can be raised and lowered to a greater extent over lighter ferromagnetic strength soils before losing proper ground balance.

Or viewing it another way Simon, there will be less latitude in the GB control adjustment to keep the coil properly ground-balanced to tough ferromagnetics, whereas there is more leeway in the GB control adjustment over lighter magnetic susceptible mineralizations. 

This discussion should help to emphasize the importance we so often reiterate on the forums about the need for suitable coil selection, for proper coil control, and  to suitably adjust the sensitivity / gain control, especially when ground-balancing to and searching tougher ground mineralizations.

Jim.  


 

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34 minutes ago, Jim Hemmingway said:

Hi Simon… you are quite right that the Fe3O4 feature is useful to evaluate soil ferromagnetic mineralization. Use the Fe3O4 readout in conjunction with the GB readout for a more complete evaluation of what general type and strength of soil minerals exist beneath the coil.

Thanks Jim, I very much appreciate your detailed reply and the time you took to author that for me, I learnt quite a bit from it.

I have tried to use my Gold Bug Pro's Fe3O4 meter to follow a black sand layer to assist me in getting good gravels for my sluice and it appeared to work, I have no way to really know however following the high readings on the meter I had a very good day 🙂

What I understand from the discussion is it has no benefit in the ground balance process other than letting you know the possible difficulties you may have balancing in the first place which then may help you decide on what coil to use or explain why you're having trouble getting a good balance in the first place.

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10 hours ago, Jim Hemmingway said:

Steve’s example to illustrate ground effects on ground balance adjustment is excellent.

This thread originated elsewhere but deserved its own thread. Here is the post Jim references above....

The combination of ground balance control and sensitivity control tells you if found is mild, moderate, or severe. If you can run the ground balance control to both extremes while at maximum sensitivity and the detector does not react to the ground when bouncing the coil over the ground, you have low mineral ground.

If the ground does react but easily ground balances to a stable setting while at maximum sensitivity you have moderate ground.

If you can't get a decent ground balance at max sensitivity then you must lower the sensitivity until the machine becomes stable enough to get a good ground balance. The lower you have to go, the more extreme your ground is.

What is considered low or high mineral ground is relative to the detector. A PI may be just fine in ground that drives a Gold Bug 2 nuts.

I don't tell my detectors what to do. My detectors tell me what to do. You need time and experience to learn how to hear what they are telling you. In simple terms, if any detector is extremely erratic, the machine is yelling at you saying "lower the sensitivity/gain". The assumption there is that the detector is working properly, there is no electrical interference, and it is ground balanced as well as can be.

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The FE304 meter is invaluable.   I'll post more when I have time sometime this week.

Mike

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I've always liked the fact that many of Dave Johnson's detector designs have ground mineralization, and Fe304 readouts.

As Steve points out, experienced folks in nugget country know from visual references of the ground itself, and machine fluctuations,  just what adjustments to make without any meters.

I often hunt freshwater beaches for jewelry, where black sand is not your friend.  Pockets of black sand (magnetite) can often be just below the surface of the normal beach sand, not visible.  Depending on it's density, it can make a detector nearly unusable, to slightly less effective, and anywhere in-between. Having the Fe304 meter in those situations as a quick reference can give an immediate indication of potential loss of the detectors effectiveness, and why.  Same with the ground mineralization meter.  Some areas can have widely fluctuating amounts of mineralization which change the machines effectiveness, and require adjustment, or just plain avoiding that area.  Having that knowledge can be helpful.

I once read a post on another forum in which the gentleman was using a fixed ground balance machine.  In only a relatively short distance he seemed to experience a severe loss in depth.  He switched to a different machine with an adjustable GB and ground mineralization indicator, I believe it was a Tek Omega.  He was surprised to see how much difference there was in the ground mineralization in the short distance.  He quantified the depth loss at approx 50%.  Having that meter to reference was a helpful tool.

Sometimes having that knowledge in ground changes can make a big difference.  I'm happy with any edge I can get.

 

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2 hours ago, EMField said:

I've always liked the fact that many of Dave Johnson's detector designs have ground mineralization, and Fe304 readouts.

I second that.  

How to say what I want to say without having to write a dissertation?   Ground balancing may null your detector's response to the ground mineral as a target, but ground balancing doesn't negate the "effects" of the mineral.   While design engineers employ filters to help with some of the effects, we are left to deal with the last effect on our own; when minerals push or pull the non-ferrous target response into the Fe response range. 

The FE304 measures the strength of the response of the ground minerals.   The higher the ground mineral strength, the greater its effect on the target signal, the more it pushes the target response up or pulls the target response down, or worse yet, even mask the target response completely.  

The FE304 meter tells you how to react to your detector's discrimination and identification methods.   When is the iron response not an iron response at all?   I've hunted sites where all the shallow quarters were iron tones.  The minerals were so high that they pushed the higher conductors over the top at very shallow depths.   The FE304 meter lets you clue into this phenomenon on purpose, rather than discovering it by accident.  The higher the FE304 graph results the more attention you pay to iron tones and your discrimination settings/patterns.   

The worst is when the ground masks the signal altogether.  I have hunted sites where I could lay a normal 3mm BB on the ground,  ground balance,  then swing over the BB and raise my sensitivity setting until the BB response broke up and then went away.   It was a 7.8 kHz unit in use, but still, the lesson is there....ground mineral strength affects us and the more we know about it the better we can hunt our treasures.  

Same hunting in salt.  The higher the reading, the more gold masking you will experience.  Its not just the ground balance null point you have to deal with it is also the strength of the mineral.

HH
Mike

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Thanks for all the wonderful replies! very appreciated.

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I think my favorite detector for providing the operator relevant information was the Fisher F5.

It's a general use detector at 7.8KHz, that does well on silver.

The display on that one has the current ground phase displayed in smaller numbers in one corner, and the current ground balance setting in the other.  All the operator has to do is keep the two readings as close as possible  through the maual GB setting, and you'll be assured of being in good ground balance.  Any changes in the ground phase, and it's constantly telling you so you can make the appropriate adjustment.  Great system!!

It has the the Fe304 meter also.  The Target ID is displayed in larger numbers right in the middle of the screen.

I always thought that model had a great layout and provided the operator important/useful info.

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