Depth Tests For Big Gold Nuggets.

Candigger, the coil used for testing at the Coiltek test site was an 18" Elite, but the one you saw on Bug's site was the 38" beastie. Awsome on big targets at depth, but believe it or not will still pick up .22 slugs. Not advisable to use it on old ground, unless you enjoy digging cans at over a meter.

your original question is almost impossible to answer......there are so many varying factors of both the detector and the operator...then lets not forget soil...salt content...moisture content...soil temp...ambient temp...and the list goes on. I see it as a positive...it's why there is so much gold left.

The best answer I can give is...yes...detectors go deep...if it's there and if it has your name on it.

Reg Wilson said:

Candigger, the coil used for testing at the Coiltek test site was an 18" Elite, but the one you saw on Bug's site was the 38" beastie. Awsome on big targets at depth, but believe it or not will still pick up .22 slugs. Not advisable to use it on old ground, unless you enjoy digging cans at over a meter.

Click to expand...

Cans at over a meter!!! No, no, too scary.

What if it was possible to have discrimination at that depth?

Goldtalk Leonora said:

The best answer I can give is...yes...detectors go deep...if it's there and if it has your name on it.

Click to expand...

Especially if I get to bury it first. Then you'll see what super depth means...... :lol: :lol: :lol:

Reg Wilson said:

...the one you saw on Bug's site was the 38" beastie. Awesome on big targets at depth, but believe it or not will still pick up .22 slugs.

Click to expand...

38" coil that pics up 0.22 grams. Hell now that's waste of time.

Candigger said:

Reg Wilson said:

...the one you saw on Bug's site was the 38" beastie. Awesome on big targets at depth, but believe it or not will still pick up .22 slugs.

Click to expand...

38" coil that pics up 0.22 grams. Hell now that's waste of time.

Click to expand...

Reg means a .22 calibre projectile which actually weighs about 2 - 3 grams.

Cheers

Doug

Candigger..Yes Normal is a much more powerful setting than Enhanced..4500s we are talking about..I would love to Run Normal, If you could It would really find that deep gold..The problem you have in Normal is that it loves ground noise..You have to be in an area where you have no mineralization..Some times I can run it in Tibbooburra where the ground is pretty quiet..But 99 % of the time its just unusable, and I Resort back to Enhanced..We have tried big and small coils , turn the Rx down to 1 but Normal still loves ground noise..Even running the Stabilisation on 1 doesnt help..When running in Enhanced in WA I use Enhanced..General..Rx 13..Target vol 20 all those vol thingys I run flat out 20..crank it up..I dont use head phones or any other amp thingys..just a speaker on my best ear..If it is too noisy I just turn the Rx down to 11..Ground balance when the 4500 gets a bit noisy and all is good..finally I run my stabiliser on 6.. Cheers..

I found this youtube video over a 31oz at 2ft interesting
https://www.youtube.com/watch?v=0V-KSXLSXBE

Rockhunter62 said:

Candigger said:

Reg Wilson said:

...the one you saw on Bug's site was the 38" beastie. Awesome on big targets at depth, but believe it or not will still pick up .22 slugs.

Click to expand...

38" coil that pics up 0.22 grams. Hell now that's waste of time.

Click to expand...

Reg means a .22 calibre projectile which actually weighs about 2 - 3 grams.

Cheers

Doug

Click to expand...

Ok I get it, but still small target for such a large coil. Must be a pain in the neck to pin point these with big coil like Reg's 38".

Ded Driver said:

I found this youtube video over a 31oz at 2ft interesting
https://www.youtube.com/watch?v=0V-KSXLSXBE

Click to expand...

The 4500 seems a bit more capable than 5000 on the 31 Oz nugget. Does anyone know with the same size 22" coil what would be the maximum depth for this 31Oz nugget to be detected?

Baldy said:

Candigger..Yes Normal is a much more powerful setting than Enhanced..4500s we are talking about..I would love to Run Normal, If you could It would really find that deep gold..The problem you have in Normal is that it loves ground noise..You have to be in an area where you have no mineralization..

Click to expand...

Yep, and that's where big DD's come into it. They handle hot ground much better than mono's, especially spiral wound monos. I'm looking forward to see what the new Nugget Finder DDs can do on those big lumps out of range of mono + smooth timing combinations.

Baldy wrote:

Candigger..Yes Normal is a much more powerful setting than Enhanced..4500s we are talking about..I would love to Run Normal, If you could It would really find that deep gold..The problem you have in Normal is that it loves ground noise..You have to be in an area where you have no mineralization..

Yep, and that's where big DD's come into it. They handle hot ground much better than mono's, especially spiral wound monos. I'm looking forward to see what the new Nugget Finder DDs can do on those big lumps out of range of mono + smooth timing combinations.

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

Right on Nenad.

But don't let the cat out of the bag yet mate.

Hey Baldy, it is possible to run normal timing on a 4500 or 5000 and on higher settings, and even over hot mineralisation, but you have to have the right coil to do this.
Things are going to change, I have seen it, and that's me in the video.

Cheers ozziegold.

ozziegold said:

Right on Nenad.
But don't let the cat out of the bag yet mate.
Hey Baldy, it is possible to run normal timing on a 4500 or 5000 and on higher settings, and even over hot mineralisation, but you have to have the right coil to do this.
Things are going to change, I have seen it, and that's me in the video.
Cheers ozziegold.

Click to expand...

Nugget Finder already have a notice on their website announcing this;
"A new Range of DD Coils for 2019
Sizes will Include 15" Round, 19" Round & 25" Round
Features Include
-Spiral Winding - Lightweight - Excellent Signal Response
-Quiet Operation in Highly Mineralised Ground
- Fantastic Ground Coverage at Maximum Depth"
:Y:

PhaseTech said:

Yep, and that's where big DD's come into it. They handle hot ground much better than mono's, especially spiral wound monos. I'm looking forward to see what the new Nugget Finder DDs can do on those big lumps out of range of mono + smooth timing combinations.

Click to expand...

Curious! Why do I see on almost every video on You Tube from Oz folks using mono's then?

Candigger said:

PhaseTech said:

Yep, and that's where big DD's come into it. They handle hot ground much better than mono's, especially spiral wound monos. I'm looking forward to see what the new Nugget Finder DDs can do on those big lumps out of range of mono + smooth timing combinations.

Click to expand...

Curious! Why do I see on almost every video on You Tube from Oz folks using mono's then?

Click to expand...

The transmit coil in a DD is half the size of the mono coil of the same size. Theoretically the mono searches deeper.

EVIE/BEE said:

Candigger said:

PhaseTech said:

Yep, and that's where big DD's come into it. They handle hot ground much better than mono's, especially spiral wound monos. I'm looking forward to see what the new Nugget Finder DDs can do on those big lumps out of range of mono + smooth timing combinations.

Click to expand...

Curious! Why do I see on almost every video on You Tube from Oz folks using mono's then?

Click to expand...

The transmit coil in a DD is half the size of the mono coil of the same size. Theoretically the mono searches deeper.

Click to expand...

and size for size, DD's are usually as bit heavier

EVIE/BEE said:

Candigger said:

PhaseTech said:

Yep, and that's where big DD's come into it. They handle hot ground much better than mono's, especially spiral wound monos. I'm looking forward to see what the new Nugget Finder DDs can do on those big lumps out of range of mono + smooth timing combinations.

Click to expand...

Curious! Why do I see on almost every video on You Tube from Oz folks using mono's then?

Click to expand...

The transmit coil in a DD is half the size of the mono coil of the same size. Theoretically the mono searches deeper.

Click to expand...

A mono and DD aren't that easily comparable and one can't so easily say one is better then the other. It is true that for the same size housing, a mono coil has a larger diameter transmit & receive coil compared to that of a DD however there is more to it than that. ML pi detectors are designed to have a transmit coil inductance of 300uH. For a mono coil, the transmit and receive coil is the same coil and hence both will have an inductance of 300uH. For a DD coil the transmit coil will also have an inductance of 300uH, however typical the inductance of the receive coil is around 450uH.

The great benefit of the latest flat wound coils is not in their ability to energize a target but their greater efficiency as a receive coil / antenna, that's why they are recognized as being more sensitive than the old stile of coils. However there is a less understood phenomenon where the transmit pulse can be refracted due to near field mineralization and hence only a small portion of the pulse will penetrate through this mineralization layer and flat wound mono coils are particularly affected by this. A good visual representation can be made using a light torch and a large glass water container. When the torch is pointing straight down the light beam will penetrate the water vertically. As the torch is rotated the light beam will be refracted off at a greater angle compared to that of the torch. Soil mineralization acts in a similar way as water. It's my belief that our ability to get through mineralized soil with the current crop of flat wound mono coils are limited by this near field mineralization refraction. It's also well known that the old DD coils were are able to punch through the near field mineralization and generally ignore it and get to deeper targets however the old DD coils lacked sensitivity due to the receive winding technique employed. I have great hopes for the new NF DD coils and I'm eagerly awaiting their relies. I just hope that Rohan has made them with a bundle wound transmit and a flat wound receive winding.

BTW the GPZ employs a DOD coil i.e. the coil is made up of one central almost rectangular transmit coil and two DD receive coils place either side of the transmit coil. Attached is a photo of a GPZ coil and a DD coil.

I was in the Beaufort/Mt Cole area (Victoria) for the last couple of weeks in hammered ground for a total of just over 70 grams including a10.7 grammer, and a 50.15 grammer @ 70cm, in ground that took over an hour of hard digging to recover from its million year hiding place (felt like I was digging rock) I was using a GPZ (14 coil) in high yield and had decided that this gully and I were done, I just couldn't find any more.
On the way out of the gully I changed the settings out of high yield to general. I could only just hear the 50.15gr nugget. As I had already been all over that spot in high yield, I set the GPZ back to high yield and NADA! NOTHING! back to general and I could just hear it, half way down the signal was inverting and I had to turn the target volume and the sensitivity down to 1 because it was blowing my head off!
So the lesson is if you set up looking for fly s__t you won't hear the deeper lumps. Depth is all in the settings and how well you can cover the ground (if you walk fast you walk past)
Before you ask. Yes I went back and spent 2 days with the 19 inch coil hoping that it had friends "it didn't" the only 2 days of the trip I didn't find anything! oh well!
ickshovel:

EVIE/BEE said:

The transmit coil in a DD is half the size of the mono coil of the same size. Theoretically the mono searches deeper.

Click to expand...

Yes, all other things being equal, and not taking ground signal into effect. Depth potential is a more complicated equation. Coil size + configuration + timing + settings - ground noise + target type - emi etc etc

You change coils and a lot of the values in that equation change, most notably ground noise.

PhaseTech said:

EVIE/BEE said:

The transmit coil in a DD is half the size of the mono coil of the same size. Theoretically the mono searches deeper.

Click to expand...

Yes, all other things being equal, and not taking ground signal into effect. Depth potential is a more complicated equation. Coil size + configuration + timing + settings - ground noise + target type - emi etc etc

You change coils and a lot of the values in that equation change, most notably ground noise.

Click to expand...

PhaseTech..I still use my SD2000, it only has the one setting as you know, just turn it on and go. No refinements, timings etc, raw unadulterated pulse induction.
I consider this setting to be the normal setting of the newer machines. The 2000 certainly cleaned out a lot of the bigger nuggets.