Our Air Tests Z14 & Z19.

Thanks Mike Good Job,

It's got me buggered why it does not Air Test well, seeing as it is sort of a VLF hybrid, and it does have to power, it is a head scratching moment that's for sure.

So it is getting 7.14% more depth on the large nugget and 22.22% on the specie.

thanks mate,

John.

hugh62 wrote:And is possible that the 30% increase   would be possible only in rather benign /quite ground ,( and by having the coil much closer to the ground ,less interference/ EMI )'' BUT ALSO''  relying much on the '' HALO EFFECT '' in order for it to interrupt the signal RX . Perhaps another software / update ?
 I must admit here too mate that its late ,and i'm thinking on the ''GO'' here too , but i'm just as curious as you and other Z owners too  

Trouble is Gold does not have a Halo effect because it is mostly pure.

Thanks for the tests, quick question - by Max Settings do you mean the Z was running in Normal?

hi all , never have i seen so much disappointment in a minelab product,
in the past its mostly been about weight or they should have had this or that ,this is to short
but also any bugs in settings that were there were worked out pretty quick and passed on through the grape vine ,
but this is not the case here ,
plenty of top prospecters have given it there best and still nothing like what was claimed ,
some people are blaming the halo of a nugget , and nugget direction and size ,
most of the nuggets tested were if not all found with older minelab technology ,
unless its a firmware update that minelab forgot to issue ,it seems nothing going to fix this problem ,
hello get over it ,
a pig is a pig even with lip stick
i hope all of you with this coil find a soluition
cheers red

Admin the above poster is associated with a certain other forum that is universally recognized for its vehement hate of all things Minelab.

alchemist wrote:Admin the above poster is associated with a certain other forum that is universally recognized for its vehement hate of all things Minelab.

Mate I can't what you are referring to ??

Redcaveman is a stirrer John, just here to have fun

alchemist wrote:Redcaveman is a stirrer John, just here to have fun

Thanks mate, didn't know that,

I do give em a serve, but I don't hate them and I do own an ML machine, and I have lost count on how much of my money I have given to them over the years

  I bet the Mrs hasn't forgot though.

John.

hi alchemist
i own an sdc2300 , ive had sd220 ,xtera70, and a sovereign gt
i like minelab stuff its the best out there at the moment
as far as s*** stiring thats your opion and im voiceing mine
cheers red

redcaveman wrote:hi alchemist
i own an sdc2300 , ive had sd220 ,xtera70, and a sovereign gt
i like minelab stuff its the best out there at the moment
as far as s*** stiring thats your opion and im voiceing mine
cheers red

OK sorry if I over-reacted but I found your comment "hello get over it" inflammatory.

If you don't like reading posts by disappointed people then don't read them, but if you do, how about a bit of commiseration.

jasong wrote:Thanks for the tests, quick question - by Max Settings do you mean the Z was running in Normal?

G'day jasong,

Yes they were both set in ground type Normal and the sensitivity was set to 20. (MAX)

Cheers.

Mike.

Ok thanks Mike, that was part of the last piece of the puzzle I had been waiting for.

It certainly seems like it's underperforming in many different settings and conditions, I don't think I've seen a result of 30% yet let alone an average of 30%. Well best of luck to all 19 owners, I can only hope that field performance bares better fruit than the air tests.

Mike54 wrote:G'day All,

We have just finished doing our tests on Tony's 618 gram nugget and our 50 gram specie.  

Air Tests between z14 & z19

Test no 1.________________________Test with max settings ____________________
Zed with 19 inch coil.                                
Factory pre set
Ground balance over ferrite
Mild ground
618grams solid gold nugget
24 inches ( dig me sound). ____________  30"

Test no 2
Zed with 14 inch coil
Same as above
23 inches ( dig me sound ).____________  28"

On a 50 gram specie
Zed with 19 inch coil
17 inches.               __________________ 22"
Zed with 14 inch coil
16 inches ☹️️ ________________________ 18"

Same tests with GPX 5000 18" elite & 14" elite coils.

Gpx 5000 18 inch elite coil, factory pre set
618 gram
22 inches
Using 14 inch elite
21 inches

50 gram specie
17 inches
Now using 14 inch elite coil
Nearly 15 inches

When We found the 50 gram specie, when We first got the Zed.. it was a good 24" deep.
So maybe if we were lucky enough to walk over a target in the ground it should punch down a bit more.. But going on what we have been reading and our tests, so far it's only getting an extra 2 to 3 inches more than the z14".  





Cheers.    

Mike.

===========================================================================================

Hi Mike 54.
This information needs an explanation into what is going on with this new method of constant current scanning.
In October last year some tests were done at the Laanecoorie test site.
I will refer only to what results we got when using this properly set up GPZ 7000.

The test targets were, an 11oz nugget a 20oz and a 28 ounce piece, or are they just colours Reg.
The nuggets, I will describe their nature, the 11oz was a dirty fairly solid specimen piece, about 3”ins L x 1.½” W x ¾” T, and shaped a bit like the horses head in a chess set.

It was mainly coated with an iron staining, and also had some pieces of ironstone adhered to it here and there.
The 2 larger pieces were similar in texture to each other, that being fairly rough and pock marked in the hollows, after them having being etched in acid, and were now minus the quartz etc, approx, 50% rough and 50% rounded off on their high spots and outer edges.

The 20 oz’s size was, 3”ins long x 2”ins wide ¾” thick, and was a little flattish.
The 28 oz’s measured, 4”ins L x 3ins W x 1.½” T, and a bit more of a lump.

The test we used first up, was to try the nuggets at 24”ins deep, placed in the PVC pipe in the side wall of the creek. Starting with the 20 ounce nugget, there was no response at all, we were astounded, and then the 28 oz was tried, damn the same thing again.

Now we were scratching our heads, the 3 nuggets were each tested now placed in the 14”inch pipe, thankfully the 7000 gave stoppable signals on all pieces, mind you not screamers as the sounds the 4500 and 5000 gave.

I then said let’s try something; we never gave the 11oz a go in the 2’ Foot hole, so it was inserted. When the coil was tried over this dirty slug there was a very faint response.

I can tell you that knocked our socks off, ----- go figure????

Cheers ozgold.

G'day ozgold 041,

I'm just wondering did the 5000/4500 pick up any of the test nuggets in the 24"/2foot test hole?? Just curious that's all. Thanks for your reply and sharing your information.

Cheers.

Mike.

ozgold 041 wrote:
===========================================================================================

Hi  Mike 54.
This information needs an explanation into what is going on with this new method of constant current scanning.

I then said let’s try something; we never gave the 11oz a go in the 2’ Foot hole, so it was inserted. When the coil was tried over this dirty slug there was a very faint response.

I can tell you that knocked our socks off, ----- go figure????

Cheers ozgold.

ozgold you might be onto a very valid point respecting CC transmission.
I was intrigued by JPs comment on the Treasure talk blog about "skin effect" here
 
High Yield is the Go-To gold mode for nuggets ranging in size from 2 grams through to approximately 2 ounces. However, this is dependent on the shape and size of the target, for instance a specimen containing many ounces can give a better response in High Yield compared to General due to the rough nature of the gold and how that irregular surface affects the way this mode creates a skin effect (eddy current) on the surface of the target.

http://www.minelab.com/anz/treasure-talk/practical-tips-for-using-the-new-gpz-19-super-d-coil

Before ZVT nobody took any notice of the skin effect because it had died out long before the sample gates opened. Traditional PI relies more on eddies being generated much deeper than the surface especially large solid LTC objects. It would appear from JPs comments that ZVT relies more upon the skin effect especially with short time constant targets. So perhaps the 30% is highly dependent upon the gold type and surface texture, a rough grainy pitted target has much more surface area for these superficial eddy currents to form.

What you had there were 2 nuggets and a nice slug, piece, color, call it what you like, but my recent 27.7 oz. nugget nearly blew my head off at about 20".  Before I dug it I could still hear it with the coil raised about a foot off the ground. As a matter of fact when I tilted the coil @ 90 degrees, running the edge of the coil over the target, as I do to judge the depth of the signal, it came through clearly. The 'sweetness' of that signal told me that it was 95% surely to be gold. I was a touch disappointed when I pulled it from the hole, as the signal suggested that it could have been larger, but that could be because not only was it a rather flat shape, but was also laying flat in the ground.
PS I was using a 7000 and standard 14" coil. Difficult ,High yield, Low smoothing, Pitch low, Threshold low, Sensitivity high, and NC headphones.

All interesting & good valid points there fellas. The main reason why I never concentrated on the "Skin Effect" is because I had already been "skinned alive" by Minelab. But still valid points & good food for thought. Now all we have to do is keep walking around missing 99% of all smooth nuggets at depth,till we find one with no skin on it.

Cheers Kon.

Mike54 wrote:G'day ozgold 041,

I'm just wondering did the 5000/4500 pick up any of the test nuggets in the 24"/2foot test hole??  Just curious that's all.  Thanks for your reply and sharing your information.    

Cheers.

Mike.  

======================================================================================

Hi Mike.

I was not going to bring on a slagging match re the 5000 against the 7000.

But the results were that a 5000 could get the 2 larger pieces at 2' ft, and an 18"inch coil was used.

Regards to you and Jen.

ozgold

Thanks alchemist (Kev),

That explains why I have found that some of the gold I've been finding size wise/shape can be heard better than others. Thanks again for the info and links.

Cheers.

Mike.

Just goes to show we need X and Z now we just need Y

It's not just a function of surface area, but how continuous that surface area is. I remember when I was doing research on EM propulsion, the way we got rid of eddy currents was to cut a bunch of notches in the driven mass. The more broken up the surface was, the harder it was for the eddy currents to establish. Break it up enough and the eddy currents became almost irrelevant. This is the mechanism by which I believe some nuggets are "invisible" to some detectors. Due to skin effect, the faster the pulse rises the less deep we had to cut into the surface for the same diminishing effect.

Have you seen that experiment where you drop a supermagnet down the center of a copper tube and it just hovers downwards very slowly due to Lenz's law? I think a guy could do the reverse and build a long solenoid, place it up and down, apply a very strong, short pulse of current through it (calculate for at least a few Teslas in the center of the solenoid), and simultaneously drop a nugget down inside, then measure the change in time it takes for the nugget to drop out of the other end compared to no current applies. The nuggets that drop the fastest establish the least amount of eddy current. Then I bet the nuggets that drop the fastest also have the smallest response to a metal detector. I guess this would be something more useful in a lab or engineering dept like at Minelab. But still, an interesting experiment to try because a person with enough nuggets could almost write a paper on what factors make a nugget more detectable or not if that measurement device worked. I think some interesting discoveries might be made, of perhaps useless relevance but it's interesting.

One potential application though: determine if the number of nuggets we miss due to geometry is on the same scale as the number we miss due to depth. If so, invent technology to find these sorts of nuggets and ignore the depth problem altogether!

Another consideration, something I touched on last year elsewhere, is that nuggets vary in purity. More relevantly, nuggets vary in purity at different depths inside the same nugget due to the silver and copper oxidizing and leaving a more pure "skin" of gold outside. That means that the higher frequency you use, the more the eddy currents are set up in purer part of the gold, due to as you mentioned, the skin effect.

by alchemist on Thu Nov 24, 2016 1:19 pm

"Just goes to show we need X and Z now we just need Y"

Luv it alchemist !  Been following this thread with interest.

Cheers
Ashley

Cheers Ashley, check out how Dale's doin

http://www.detectorprospector.com/forum/topic/2645-first-nugget-4-19in-coil/

Thanks for that alchemist, Been watching for a posting from Dale. He did good !

Cheers
Ashley

Well looks like someone has a 13" improvement over your test Mike with a very similar size specie come on mate what are you doing

rc62burke wrote:  Well looks like someone has a 13" improvement over your test Mike with a very similar size specie  come on mate what are you doing    

Yes Lee, I can see what you are saying, but did you read what I wrote at the bottom of the test page.  In case you missed it when we found that particular specie (which is 50grms) it was at a depth of 24"=609mm using the standard Z14x13 coil on the GPZ 7000 and this was our first time in the field with the new detector and had no idea how to setup it up.  The target signal on this specie was a very definite dig me signal.  
Don't forget there's many veriables and our tests were after all only air tests.  Nothing personal here, but I'm just stating the facts.    

Cheers.

Mike.

Sorry I forgot to congratulate Dale for his nice find and wish him luck for the rest of his season as well and hope there's many more where that one came from. To you Dale and the other Goldhounds.

Cheers.

Mike.

Fantastic news & well done Dale. Now can I ask you what settings you were in & please don't say "Normal" or its back to the drawing board for us.

Cheers Kon.

Mike54 wrote:

rc62burke wrote:  Well looks like someone has a 13" improvement over your test Mike with a very similar size specie  come on mate what are you doing    

Yes Lee, I can see what you are saying, but did you read what I wrote at the bottom of the test page.  In case you missed it when we found that particular specie (which is 50grms) it was at a depth of 24"=609mm using the standard Z14x13 coil on the GPZ 7000 and this was our first time in the field with the new detector and had no idea how to setup it up.  The target signal on this specie was a very definite dig me signal.  
Don't forget there's many veriables and our tests were after all only air tests.  Nothing personal here, but I'm just stating the facts.    

Cheers.

Mike.

Mate just a bit of harmless fun

Well done Dale , I hope you didn't use the same ruler as you did when depth testing the ctx3030 that cost me $600