GPZ Low-high Signals And High Yield Vs General

[jasong]

Still larger stuff is mainly high/low although I think to save confusion perhaps we should call it reverse or high/low/high

 

You mean low-high right? Otherwise you are confirming my alloy/purity thoughts above since you are in lower avg purity gold (similar to my own) and Gold Hound is in higher avg purity. 

 

Yeah, better to call it a reverse signal.

 

Any GPZ owners out there also jewelers? And interesting test would be to test increasingly larger 24k rings until the signal reverses, then test an identical sized 10k or 14k ring and see if the signal goes back to high-low. If so, it has to be due to the silver/copper in the ring, and presumably the same would apply to nuggets. If not, then the signal reversal must be due to geometry (porosity, crystal faces, overall shape, etc) and does not have anything to do with alloys. Assuming of course the ring shape itself doesn't produce a reverse signal to begin with, it might be warbly. Maybe a gold bar shape is better.

[Norvic]

Yeah, looks like I was the one most confused, most large nuggets give a reverse signal in my country, regardless of purity. Sorry about that, Senile Moment.

 

On varnish, I no longer use epoxies, have found the acrylics are just as tough and much easier to apply, although on high wear bench tops go for 8 coats min.

[Norvic]

Jasong. re. Conductivity of nuggets. I don`t know if the below is too relevant, as shape of nuggets etc will influence. But ID air test of the below  on a XP Deus with ID set at norm (same across frequencies)

 

58gram solid nugget (round)            86% AU      ID 92

  4gram  nugget (flat)                        86% AU      ID 74

  4gram  nugget (flat)                        78% AU      ID 51

  4gram specimen (est 2gramAU)     86% AU     ID 63

 1/2 AU gold sovereign                                        ID 70

 

Note the 78% nuggets ID. Perhaps of interest.

[Steve Herschbach]

The GPZ although not a PI does share some similarities and the tones are an artifact of the ground balance system similar to that seen on a ground balancing PI. A hi-lo tone basically means small target or low conductive target. A lo-hi tone means large target / high conductive target.

The size, shape, and density of the nugget specimen all play into it as does the machine settings. Pure silver is extremely conductive. Pure gold is very conductive. However, when you add silver to gold the conductivity does not increase, it decreases dramatically.

The GPZ so far acts pretty much like I would expect a GBPI to react as far as tones go. See Coin Detecting with the Garrett Infinium and Beach Detecting with a Minelab GP 3500 for reference.

I use this all the time. If you are in an area with large junk and sub gram nuggets, just dig hi-lo tones. Always a risk you could miss a huge nugget but that is where knowing your ground and the odds come in.

Conversely, chasing big gold in the midst of lots of tiny ferrous trash? Dig only lo-hi tones.

Again however, due to the huge variation in the nature of gold and where it is found, this is all at your own risk using your own knowledge and experience as a guide. Be aware tones do change depending on the "timings" or "ground settings" or anything that might affect the ground balance of the detector.

This is not VLF type discrimination but can work. Unfortunately no manufacturer has explored formalizing the responses with the exception of White's and the TDI. The real trick to making it work is to understand why it does what it does and then do apply it with care where it might help your odds, but never get complacent in relying on it.

Great informative spreadsheet for TDI settings and how responses on bullets and buttons change with ground balance and pulse delay setting

The GPZ should be able to collect information from targets allowing it to perform classic phase based discrimination as used in most VLF detectors. Or something more akin to that used in the BBS/FBS detectors.

[Norvic]

Steve, many thanks for references to your posts re. conductivity vs signal. Yes the Z is much similar to the PIs in the signal it gives, I have found the solid nuggets once over about 12 gram give a reverse signal, but it is not always correct just a rough guide. Sometimes a sub grammer gives a reverse signal. Only really one for sure rule, dig em all.

[Lunk]

Jasong,

The 29 grammer I posted about here: http://www.detectorprospector.com/forum/topic/1572-nice-lump/was initially a warbly response in High Yield\Normal; the warble solidified into a solid high-low response after I took about 8 or 10 inches of soil out of the hole. Passing the coil over the nugget in General\Difficult gives a reverse, low-high response.

[Norvic]

Over the years, experiencing these reverse signals I suspect you`ve basically nailed it Lunk. It seems to be a GB "condition" that doesn`t necessarily have much to do with gold, size or purity. GB settings and ground conditions, but saying this next one will go against this.

[Lunk]

Indeed Norvic, I have learned over the years that trying to glean information about a target from the tones of the detector is iffy at best, and if relied upon can cost you gold.

[flakmagnet]

Lunk you are so right.

It is easy to get fooled by the tones.

If it's making any sort repeatable tone, get after it.

[Steve Herschbach]

Dig it all is always the answer. Except when it is not. Late in the day, tired, lots of trash around, I may just start cherry picking. I am one that says dig it all but who often cherry picks. Reality in the form of overwhelming trash can change my mind pretty quick. It's either that or break out the VLF.