Chasing Stupidly Small Gold Continued And A Dramatic Rescue

[flakmagnet]

Mistaken post :)

[GB_Amateur]

Great post, flakmagnet; thanks for sharing.  All of us who inhabit this planet need to respect it but particularly those of us who use more of it -- filling our holes (and those holes left by the idiots), carrying out our trash and that of others, and especially protecting the wildlife.  It's their home, we are merely visitors.

 

[beatup]

Well done Flakmagnet

[PeterInSa]

kiwijw re ( Keeping the coil virtually scrubbing the ground, as you can't get any closer to gold than that),

I understood when I purchased the 7k that the coil should approx 2inches off the ground when detecting, unlike  my years of close to the ground detecting with the 4500. Only last year have I moved to a close to the ground approach recommended by a friend as keeping the weight of the coil off the ground was killing my back.

I wonder did I get the wrong info back when I purchased the 7K years ago, or when did the detecting method change. I have found very small gold in WA with the off the ground approach and not so much in the Vic Golden Triangle mainly because I have not spent the time there with the 7k.

[flakmagnet]

I would rather defer to more experienced people than me as to what is best. For myself I vary what I do. Sometimes I basically scrub the coil and sometimes I keep it 1/2 of an inch or so off the ground. I don't know which is better, I find gold using both methods.

[Northeast]

8 hours ago, PeterInSa said:

I wonder did I get the wrong info back when I purchased the 7K years ago, or when did the detecting method change.

When I had the Z I most gently rolled across the surface. It helped with weight support and also finding the tiddlers.  Where I detect I was able to do this.  

But, and I am sure JP will confirm or deny this, I am sure I read a thing from JP where he suggested running the Z coil 1-2 inches off the ground particularly in saturable ground.  I think the reasoning was that if the detector was simply unusable at ground level then being 2 inches closer to the gold was no advantage.  However, if by running 2 inches off the ground you could still detect then at least you were still in the game.  As always JP, feel free to correct me  ?

Edit - actually it was Steve H - half way down the first post.   https://www.detectorprospector.com/forums/topic/970-minelab-gpz-7000-a-super-vlf-saturable-soil-tips/

[Gerry in Idaho]

In my memory of detector manuals, most wanted you to keep the coil off the ground and there are different heights per model of detector, but 2" was mentioned many times.  Now I know for a fact when my staff and I train customers, we want them to keep it as close to the ground as possible.  The reality of it is, the ground type/structure I am sweeping over.  If really rough ground with many rocks and cobbles, I'll keep the coil just above.  If it is smoother ground, I like to let the coil slide across the ground.  Now on occasion extremely hot ground is encountered and when GB'ing, I notice detector won't keep up, then I adjust the coil height to stay in the "happy medium".

Another issue I run into with the 7000 and others.  If it is really hot temperature outside and I don't want to wear headphones, then I'll lift the coil and set my bungee just above ground level, so I am not hearing the coil skid across the ground as the noise it makes does not allow me to hear the faintest of potential signals.  Most folks who know me, will tell you, I prefer to wear headphones when using a GPZ, as the coil is usually making noise as it scuffs the ground quite regularly.  

Now when using other machines or chasing bigger gold or new ground, my mind is more in a cruise mode trying to find the indicator nugget.  Then my coil is usually a little higher (1/2 to 1") off the ground.

Like others have said and I feel the same way.  In most ground I hunt with a 7, the 2" off is a loss of 2" in depth.  But in reality, just like settings and threshold level, there is no right and wrong, just more of a what do you feel comfortable with. If you are happy with your results, then I'm happy for you.

As for different coils and some other detector models?  I have had units, that could not even be used scuffing the ground because the detector and coil would make to much noise.  I myself attribute that to a bad coil.  The Fisher GB-2, small 6" ellip coil had had a change when they moved from Los Banos, CA to Texas and for about a year, the coils being made, had a high % bad coils.  I think I was on their shit list for a while, as I would send them back multiple coils telling them they were bad.  They would argue with me saying the tested just fine.  Now the coil has changed design, so that goes to show there was some issues, plus a few other things inside, but they have a handle on it now and those small gold grabber 6" ellip coils can be used on the ground.

Bottom line:  If you're not wearing out your coil cover, you are missing gold.

[flakmagnet]

7 hours ago, Gerry in Idaho said:

Bottom line:  If you're not wearing out your coil cover, you are missing gold.

I am on my second coil cover if that says anything (I am not out all that often until lately). I also remember JP recommending having the coil off the ground i.e. not scrubbing and there was a reason for it but I can't remember if it was to keep the detector from being oversaturated. JP?

[Jonathan Porter]

How close you can get the coil to the ground is determined by how much saturation signal is present. Saturation is caused by highly magnetic materials affecting the Tx creating a slight current change that is manifest as a response in the audio. If Saturation is present that response is going to impede a target signal or at the very least compete with it, especially the edge of detection ones. Any noise that is not signal related is counter productive, any noise that you can have a control over it is highly desirable to modify the way you use the detector to avoid it impeding performance. 

In the first video the coil is saturating really badly, so badly that the coil cannot even touch the ground without a loud response, clearly the only way to detect in this instance is to keep the coil above Saturation and try to allow any target signals the come through. And yes in this instance a lot of depth is lost because the coil has to be held further away

In the next video that was filmed on the same ground using the standard GPZ14 coil you can see there is some slight saturation noise when I couple the coil to the ground but the coil can be swung much closer to the ground so therefore the GPZ14 coil in this instance has a close on 2 inch depth advantage over the previous coil. This is why I harp on so much about Saturation signal killing performance, a well designed coil will Saturate as little as possible. 

In the GPZ14 video you can see from the side shot how close the coil can come to the ground to achieve a ground balance (I actually couple the coil to the ground towards the end, you will note the Saturation is minimal with the GPZ14), any closer and there is a constant faint signal when the coil is pumped up and down. In the top video you can see where I pump the coil initially to achieve a GB but then see how far I actually have to lower the coil to be able to couple to the ground, in that ground that is how far up I need to hold the coil to avoid the Saturation signal from interfering with target signal.

If the ground does not Saturate then by all means scrub the ground, the only thing against you is wearing out the skid plate, clipping the ground preventing a smooth pass of the coil which is required to get a good rang of motion and creating physical noise that might impede your ability to hear a faint target. 

JP

Post Note: A highly sensitive coil will give a good response to tiny surface targets that are louder or stand out from the Saturation signal, this can give a false impression of depth if you scrub the coil. Deeper target performance gets killed by Saturation signal because the level of volume they can achieve is far far less than the Saturation signal so they get drowned out. SFERIC noise also KILLS depth in the same way, dependant on how much of either of these signals gets into the audio determines the percentage of outright performance lost.