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#1

PhaseTech
Phase Technical
From: Adelaide, SA
Joined: 29 May 2014
Posts: 1,937
Phase Technical
20 June 2019 03:47 pm

Well I finally had a couple hours to take the coil out. With my limited time I wanted to initially get a feel for the coil and what it is capable of, so just took it to my test patch to Jupiter Creek. The ground at this spot is not what I'd call super hot, maybe a 5.5/10 on the mineralisation scale, but there are patches of hot clay, and the ground being saturated at the moment definitely woke up the mineralisation that is there, taking it to a 7/10.

I've got about 2 pages of testing notes which I don't have time to type up in it's entirety, so I'll highlight a few interesting observations.

Yes it ran beautifully in Normal/DD on both the 4500 & 5000. There is no way I could run the 19" Evo in Normal - it was moaning and carrying on, even with the Rx Gain dropped to 5 on the 5000.

It was less affected by EMI compared to the 19" Evo in Fine Gold and Enhance. Stability wise it was as stable as the 14x9". Not bad for such a big coil.

Weight - yes it's a little heavy, but with the control box pushed back, and with my stock pro-swing bungy, it felt fine. Much lighter overall than the 7000 and Z19 combo. Remember this is not an every day coil, it is a specialist coil that you'll pull out in areas you suspect some big lumps may be lurking.

On my test patch I have a "hard" target. It is a hackly bit of lead that was buried at an angle and at depth (can't remember exact depth), but they key thing is that many detectors and coils struggle on it. The 15" Evo in Enhance sees it most consistently, but the target signal is a faint drop tone or sometimes a wobble, and you have to have perfect coil control and speed in order for it to pull you up. With the 25" running in Normal/DD it surprisingly got it easy, and it was a traditional High/Low signal! This was most impressive, as I was expecting a much larger target would be needed to see the benefit of this coil.
Not surprisingly was the fact it smashed the 7g lump of lead at 40cm+.

I did a bunch of air tests just out of interest, ground balancing each coil over the exact same patch of ground. Here's a few interesting comparisons:

Target 1 - 2.35g nugget:

5000 - 14x9" Evo - FG - 19.5cm
4500 - 19" Evo - Enhance - 24cm
4500 - 19" Evo - Normal - 32cm
4500 - 25" XDD - Normal - 32cm
4500 - 25" XDD - Sens Extra & Mono - 34cm

So the 19" in Normal could match the 25" but remember, it was impossible to run the 19" in Normal on that ground. The added depth in Sens Extra and Mono on the coil switch was a real eye opener but kind of what you'd expect on a relatively small target, but the thing that has me excited is that it also ran great across the ground!
Now I probably should mention, I wasn't playing around with any menu settings to optimise each coil and timing selection as that would take weeks to factor in all the variables, so settings were pretty much factory settings, with Volume & Signal slightly up as I always do. Gain on the 4500 was 8, and on the 5000 - 10.

Target 2 - 50c coin

5000 - 14x9" Evo - F Gold - 51cm
4500 - 15" Evo - Enhance - 61cm
5000 - 19" Evo - Normal - 64cm
4500 - 19" Evo - Enhance - 65cm
4500 & 5000 - 25" XDD - Normal - 66cm
4500 & 5000 - 25" XDD - S Extra & Mono - 67cm

Not a lot of surprises here, big DD coil in Normal doing what it is supposed to do, better depth on bigger targets, but again that Sensitive Extra and Mono combo is going to be deadly in less mineralised ground. Also proved the 19" Evo on the 4500 is a bit of beast as well and did very well on my test bed too.

I leave it there for now as that is a fair bit to digest, and I'm still pouring over my results thinking of where I might get some results in the field.....


Agent for Minelab, Nugget Finder, Nokta & Makro, Quest, Detech, SteelPhase - Phase Technical Website

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#2

Ded Driver
Member
From: West of the Border, WA
Joined: 27 May 2018
Posts: 2,164
Member
20 June 2019 03:53 pm

interesting. very good 1st impressions Id say Nenad! gold-nugget thumbsup


APLA member, GPX4000, modded SD2100, XTerra705, GM1000, Whites MXT Pro, Nokta Pointer, sP01 Enhancer, Garmin GPSMAP 64S, kti PLB, a map, all sorts of coils & a cupla buckets full of hope & enthusiasm

#3

Jaros
Moderator
From: S.E.Qld., QLD
Joined: 11 August 2013
Posts: 11,418
Moderator
20 June 2019 04:30 pm

thumbsup


F1A4M2, Exterra 705 Gold, Ace 250, Goldrat 8" Dreammat River Sluice.

#4

HoudiniHarry
Member
From: GT, VIC
Joined: 09 November 2016
Posts: 1,193
Member
20 June 2019 04:37 pm

Now that is going to produce some really deep holes.

Cheers HH


Having a great time searching for gold....
GPX4500

1 user likes this post: mxt sniper

#5

Muza
Member
From: W.A
Joined: 09 June 2019
Posts: 174
Member
20 June 2019 05:26 pm

I am looking at getting one of these coils, they look promising! Have been pulling my hair out trying to find some actual field tests with it though.
Cheers Mr Nenad, good work thumbsup


Gpx 5000

1 user likes this post: PhaseTech

#6

PhaseTech
Phase Technical
From: Adelaide, SA
Joined: 29 May 2014
Posts: 1,937
Phase Technical
21 June 2019 12:06 pm

Here's some more results on a more sizeable target

Target 3 - 96g Flat Lead slab

5000 - 14x9" Evo - F Gold - 49cm
4500 - 14x9" Evo - Enhance - 50cm
5000 - 14x9" Evo - Normal - 52cm

4500 - 15" Evo - Enhance - 56.5cm

5000 - 19" Evo - F Gold - 63.5cm
4500 - 19" Evo - Enhance - 64cm

4500 & 5000 - 25" XDD - Normal - 64cm
4500 & 5000 - 25" XDD - S Extra & Mono - 69cm

pickshovel


Agent for Minelab, Nugget Finder, Nokta & Makro, Quest, Detech, SteelPhase - Phase Technical Website

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#7

madtuna
Member
From: , WA
Joined: 12 December 2012
Posts: 2,317
Member
21 June 2019 12:17 pm

"Remember this is not an every day coil, it is a specialist coil that you'll pull out in areas you suspect some big lumps may be lurking."

thumbsup


If guns kill people, cutlery causes obesity. Sporks should be Cat D and have no place in suburbia
https://www.youtube.com/channel/UCL9zIt … KCVngVrjg?

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#8

Happy Jack
Member
From: Batemans Bay, NSW
Joined: 07 September 2015
Posts: 30
Member
21 June 2019 01:33 pm

Well done Nenad...what a great write up. I am so looking forward to the other XDD coils coming out and will always have one or two in my arsenal. I can see a 15 XDD on the end of my 4500 in areas down here on the NSW far south coast where monos struggle on the hot clay domes.

Jack

#9

Dignit
Member
From: Melb Eastern Suburbs, VIC
Joined: 15 May 2015
Posts: 1,682
Member
21 June 2019 05:58 pm

Happy Jack wrote:

Well done Nenad...what a great write up. I am so looking forward to the other XDD coils coming out and will always have one or two in my arsenal. I can see a 15 XDD on the end of my 4500 in areas down here on the NSW far south coast where monos struggle on the hot clay domes.

Jack

Will the XDD actually be better than a mono on hot clay domes?
And if it will be what is the technical reason?
Just curious if someone would explain.
Cheers


GPX 4500, pick, Jeep Cherokee and gold fever

#10

PhaseTech
Phase Technical
From: Adelaide, SA
Joined: 29 May 2014
Posts: 1,937
Phase Technical
21 June 2019 07:05 pm

Assuming the same timing is used on both coils, then the X-Search DD as well as most other DD's will be less affected than the Mono.
But then the timing also plays a part in the result. I.e. Sensitive Smooth with a big bundle wound mono would pretty much ignore most clay domes, whereas a 14x9" Evo in Fine Gold will still be affected by the odd one. Then there is soil moisture.....and the list of variables grows


Agent for Minelab, Nugget Finder, Nokta & Makro, Quest, Detech, SteelPhase - Phase Technical Website

1 user likes this post: mbasko

#11

mbasko
Member
From: Central West NSW
Joined: 27 January 2015
Posts: 4,022
Member
21 June 2019 07:28 pm

By design DD coils are less susceptible to noise from ground mineralisation, ground moisure, charcoal etc. as well as EMI.

It is my understanding this is due to the configuration of the DD - i.e. 2 x D shaped loops that overlap in the centre.
The DD configuration cancels out these signals above that would normally cause interference in a mono coil.

Mono coils detect signals in a sort of a triangular shape detection pattern being wide at the top to a point at max depth (like in the diagram I previously posted).
This area or detection pattern is known as a positive detection field.

The positive detection field of a DD coil is only the centre section (like an "I" beam as per the previously posted diagram).
The right & left D loops on each side are a negative detection field - meaning that they give the DD coils the cancelling effect.

The new NF XDD coils have no other "magic" than other DD coils (as far as I'm aware but happy to be corrected) other than being part bundle wound & part spiral wound which I'm guessing would be to maintain the DD cancelling characteristics but also enhance sensitivity over normal bundle wound DD coils.


Everything we use comes from mining or farming.

1 user likes this post: Trash

#12

Dignit
Member
From: Melb Eastern Suburbs, VIC
Joined: 15 May 2015
Posts: 1,682
Member
21 June 2019 07:34 pm

I agree, moisture in clay causes much more noise, and it can be a loud broad signal. You could swear it’s a target, but when the clay coming out of the hole sounds off like the clay in the hole, and you can ground balance it out, you know it’s just the wet mineralised clay. Bugga!


GPX 4500, pick, Jeep Cherokee and gold fever

#13

10fp
Member
From: Adelaide
Joined: 16 December 2015
Posts: 159
Member
21 June 2019 10:55 pm

We’re over here in WA. at leanora , Carnegie and Yandal and the big 25 runs sweet in sens extra no worries


Sdc , 4500, NOX 800, QED

1 user likes this post: Muza

#14

wiley coyote
Member
Joined: 21 May 2016
Posts: 87
Member
22 June 2019 01:46 am

Being so large and powerful, does the coil produce any signal from the detector box when swinging it,or any other metallic objects on your equipment?

#15

stevewilko
Member
From: West Of Melbourne, VIC
Joined: 17 October 2016
Posts: 128
Member
22 June 2019 09:33 am

Hi All..

From the last line of the test result x Nenad I read

4500 & 5000 - 25" XDD - S Extra & Mono - 69cm.

Am I correct in understanding as this is in mono selection - this as 'half' the 25XDD is in operation, viz, this equates to a 12.5 mono?

Seems an out of line result @ 69 cm as per my understanding.

Is this a valid equation of mine ?

Thank you,
wilko.


Thanking all contributors for their involvement and the quality of these posts. Prospecting with - GPX 4800 / 11" DD / 15 x 12 Mono / 15" DD / 18" NF Mono / NF 25"X DD

#16

Dignit
Member
From: Melb Eastern Suburbs, VIC
Joined: 15 May 2015
Posts: 1,682
Member
22 June 2019 10:07 am

Hi Wilco
I believe you are correct.
But consider it as a 25x12.5 mono and in Sens Extra.
When you compare to the 14x9 result of 50 & 52cm in enhance & normal respectively it seems an in line and feasible result. Though a little surprising. Just my thoughts. Cheers

Last edited by Dignit (22 June 2019 10:07 am)


GPX 4500, pick, Jeep Cherokee and gold fever

1 user likes this post: stevewilko

#17

Chrisco
Member
Joined: 24 September 2015
Posts: 22
Member
22 June 2019 10:05 pm

Hey Nenad,
Next time your out testing could you do an air test on an empty unflattened 375ml aluminium soft drink can and post the result?
I would be very interested to know the maximum distance it will pick this up in the air.

Thanks
Chris

#18

Baldy
Member
Joined: 09 July 2015
Posts: 543
Member
23 June 2019 12:25 am

Chrisco, just tried that the other day with a can crunched about the size as your palm..on sensitive extra about 5 feet..Not bad..


Swinging a 4500 , 2300 .Digging a Keen 140 Dry blower, Smashing dolly pot, Laying back in a Chair..

1 user likes this post: Ded Driver

#19

Chrisco
Member
Joined: 24 September 2015
Posts: 22
Member
23 June 2019 10:10 am

Thanks Baldy, that’s a good depth indeed!
I would like to see a measured test on the uncrushed can though as it is a universal size that we can compare to.
When it’s crushed the size and shape can vary.
A measured result is a bit more accurate for us to compare too, rather than an estimate.
I would love to see the results if anyone has time. You can also rest the coil on the ground and move the can above it and measure the distance if it’s too hard getting the coil above the can to measure.
Be interested in the response in normal too.

Thanks for the time and effort to those doing the tests

Chris

#20

PhaseTech
Phase Technical
From: Adelaide, SA
Joined: 29 May 2014
Posts: 1,937
Phase Technical
24 June 2019 01:49 am

stevewilko wrote:

Hi All..

Am I correct in understanding as this is in mono selection - this as 'half' the 25XDD is in operation, viz, this equates to a 12.5 mono?

Thank you,
wilko.

Not exactly. When you flick a DD into Mono mode, instead of just the right hand Rx winding doing the receiving, the whole coil or more accurately the Tx and Rx windings both receive. So your resultant search field would be a little wider than half the coils diameter. It may be closer to 25 x 16 or so....

This "pseudo mono" mode of operation can produce some interesting results, and has over the years, but it's effectiveness varies depending on what DD coil you are using. Every time I put a new DD coil on, I play around with the Coil/Rx switch as well as different timings to see what it might be capable of, as it is extra functionality you have (on a GP or GPX) which you don't have when using a Mono coil.

Now, as Mbasko mentioned, the 25" X-Search is half flat wound, half bundle wound, so when using Mono mode, you are getting a bit of that flat wind efficiency in the Receive pulse. So I guess it makes sense that Mono mode on this coil will perform a little different to what we've come to expect from a traditional DD coil.


Agent for Minelab, Nugget Finder, Nokta & Makro, Quest, Detech, SteelPhase - Phase Technical Website

1 user likes this post: stevewilko

#21

Candigger
Member
Joined: 03 January 2019
Posts: 126
Member
24 June 2019 05:46 am

stevewilko wrote:

Hi All..

From the last line of the test result x Nenad I read

4500 & 5000 - 25" XDD - S Extra & Mono - 69cm.

Am I correct in understanding as this is in mono selection - this as 'half' the 25XDD is in operation, viz, this equates to a 12.5 mono?

Seems an out of line result @ 69 cm as per my understanding.

Is this a valid equation of mine ?

Thank you,
wilko.

Actually, because of the overlapping between TX and RX the TX alone will be equal to about a 19" (approximately 25"x14") or so mono coil, hence the similarities in results between 19" Evo and 25"XDD(in mono mode). In ideal circumstance the 19" Evo will display a pinch better results as it is a circular in shape therefore more efficient than a D shaped TX. Any bigger than 19" Mono would be deeper than the 25"XDD.

1 user likes this post: stevewilko

#22

stevewilko
Member
From: West Of Melbourne, VIC
Joined: 17 October 2016
Posts: 128
Member
30 August 2019 12:53 pm

Hi All

A relative size comparison if you will.

If you have been considering just how large the NF 25"X DD is and have perhaps been running a tape over a table or the floor, (as I did!!)...this photo might assist!

This is a 14" wheel with a 185 14 60C L/T tyre comparison.

There are only millimetres in size difference.

1567129517_nf_25x_dd_size_comparison.jpg

Thanks to Nenad for this supply and for all his assistance throughout the forum.

Cheers stevewilko


Thanking all contributors for their involvement and the quality of these posts. Prospecting with - GPX 4800 / 11" DD / 15 x 12 Mono / 15" DD / 18" NF Mono / NF 25"X DD

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#23

PhaseTech
Phase Technical
From: Adelaide, SA
Joined: 29 May 2014
Posts: 1,937
Phase Technical
02 October 2019 03:30 pm

Here's a nice slug found with the 25" DD


Agent for Minelab, Nugget Finder, Nokta & Makro, Quest, Detech, SteelPhase - Phase Technical Website

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#24

Skip
Member
Joined: 02 October 2018
Posts: 253
Member
02 October 2019 08:10 pm

Nice slug! Think If I ever get of one these coils i'd have a smaller coil handy after a few hits with the pick Just so you dont need an earth mover to get to the nugget.
That's almost mining!


The great out doors.. this is livin

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#25

Northeast
Member
Joined: 27 August 2016
Posts: 1,151
Member
02 October 2019 08:33 pm

It is a nice piece. Shout yourself a pin pointer with your $800 of gold young fella thumbsup gold-nugget money pickshovel

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