Aftermarket Coils for the GPX 6000 - Nugget Finder

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That’s not correct - no issue with larger coils
What bit is not correct?
There is plenty of speculation on other forums that the 6000 will not work well with bigger mono coils, just look on DP for a start.
A lot of people have also used the 17x13 ML and gone back to the 11, rare to see many apart from the odd user actually having the 17 on their 6000, I personally think its the smaller cousin of the 19" GPZ 7000 (dog) coil, the coil that we all bought because it was big and then found out it wasn't much good.
The speculation IS out there, the truth of it, who knows?
 
What bit is not correct?
There is plenty of speculation on other forums that the 6000 will not work well with bigger mono coils, just look on DP for a start.
A lot of people have also used the 17x13 ML and gone back to the 11, rare to see many apart from the odd user actually having the 17 on their 6000, I personally think its the smaller cousin of the 19" GPZ 7000 (dog) coil, the coil that we all bought because it was big and then found out it wasn't much good.
The speculation IS out there, the truth of it, who knows?
Speculation being the key word:
the forming of a theory or conjecture without firm evidence.
I'm assuming GemQ has used a bigger coil (Coiltek prototype perhaps 😇😉) & like me hasn't seen any problems using one.
I was sceptical at first on depth with the 17x13, but after using it a bit more last year, it appears to be ok & has certainly pinged some deep targets for me.
That's not to say everyone would be happy with it & no doubt there are some people that might find it less than they expected in their area.
Speculation isn't really helpful though.
I find the whole "the GPX6000 won't get big or deep gold" banter laughable to be honest as I've pinged some decent bits at good depths.

All large coils seem to get a bit of bad feedback at times. There's a lot of people that seem to think by putting on a bigger coil (on any detector) the big, deep gold should just jump out of the ground for them.
As anyone that's spent time going over areas with a larger coil knows it can be a long & sometimes fruitless process. The big, deep gold isn't always there.
 
Speculation being the key word:

I'm assuming GemQ has used a bigger coil (Coiltek prototype perhaps 😇😉) & like me hasn't seen any problems using one.
I was sceptical at first on depth with the 17x13, but after using it a bit more last year, it appears to be ok & has certainly pinged some deep targets for me.
That's not to say everyone would be happy with it & no doubt there are some people that might find it less than they expected in their area.
Speculation isn't really helpful though.
I find the whole "the GPX6000 won't get big or deep gold" banter laughable to be honest as I've pinged some decent bits at good depths.

All large coils seem to get a bit of bad feedback at times. There's a lot of people that seem to think by putting on a bigger coil (on any detector) the big, deep gold should just jump out of the ground for them.
As anyone that's spent time going over areas with a larger coil knows it can be a long & sometimes fruitless process. The big, deep gold isn't always there.
First off, I really like the 6000 and I am not in the "the GPX6000 won't get big or deep gold" club at all.
We have found many multi ounce pieces with ours.
My partner apart from two very brief stints trying out the NF exceed 12x7 and the Coiltek 14x9 Goldhawk has exclusively used the 11"ML.
I on the other hand have been constantly swapping between those calls as well as the 17"ML and 14"ML DD.
My partner will not carry a pick (she says it slows her down lol) . Where we operate mainly most (90%+) nuggets are in the top 2-3 inches and easily retrieved with just a scoop so this is not a major issue.
So when she finds a deeper nugget I wander over and dig it for her.
This gives me an opportunity to compare whatever coil I have on against her 11 ML, we have been doing this since we obtained the 6000's among the very first batch.

My observations in our highly mineralised ground over many thousands of nuggets are,
1. We have had quite a few nuggets found with the 11 that the 17 won't pick up even with 2-3 inches topsoil taken away.
2. Both the NF and Coiltek coils mentioned are not as good as the standard 11ML close but not as good with the NF slightly exceeding the Coiltek, this was a surprise to me as have always preferred aftermarket coils on our other Minelab machines apart from the 2300.
3. The 14" DD is a strange one, definitely gets fewer nuggets and is shallower than the 11 on nuggets but it finds many more specys per use time than any of the other coils.

A further comment would be that even though we prefer the 11 over the aftermarket (NF and CT) coils the aftermarket ones seem more resilient as we have returned and had replaced 6, yes SIX ML 11 coils that have definitely been faulty and one 17 that may have may not have been faulty but was tested and replaced.

There is SPECULATION ( that word again ) and photo's on other forums (DP being one) where coil makers have taken apart 6000 coils and found generally what they consider poor shielding and misplaced ground wires in them. I don't know as not a coil winder or electronics expert.

What is somewhat disturbing is why after over a year of promoting a bigger coil NF has now taken all reference to it away?All know that if produced it would be a best seller.

I have been eagerly awaiting this most probably along with thousands of others as a 6000 with a large well functioning coil would be a killer.
 
yep I use the 11" mono standard coil on the 6000 and well yes it does detect deep, and shallow and works very well, this is a hole I/we dug the other day in VIC, the piece of cast iron wheel was sitting end on not laying flat and at the surface was a nice low/high tone the ones you like to hear, so of course your going to dig it, the handle on the pick is 700mm long so the hole was at least 600mm to 650mm deep a full arms length with the scoop getting the loose dirt out after digging away at it with the pick.

Anyway after taking turns digging when it got fairly deep and widening the hole a few times to get the pick in to dig more, finally exposed to end of the broken cast iron wheel piece.

Better to have dug it than wondered what it was :rolleyes:🤔👍

so yes the 6000 will go deep and with the 11"
423472461_1462503071146539_5945483913586042019_n.jpg
cheers dave
 
Speculation being the key word:

I'm assuming GemQ has used a bigger coil (Coiltek prototype perhaps 😇😉) & like me hasn't seen any problems using one.
I was sceptical at first on depth with the 17x13, but after using it a bit more last year, it appears to be ok & has certainly pinged some deep targets for me.
That's not to say everyone would be happy with it & no doubt there are some people that might find it less than they expected in their area.
Speculation isn't really helpful though.
I find the whole "the GPX6000 won't get big or deep gold" banter laughable to be honest as I've pinged some decent bits at good depths.

All large coils seem to get a bit of bad feedback at times. There's a lot of people that seem to think by putting on a bigger coil (on any detector) the big, deep gold should just jump out of the ground for them.
As anyone that's spent time going over areas with a larger coil knows it can be a long & sometimes fruitless process. The big, deep gold isn't always there.
My lips are sealed but can’t agree more with what you have said. I have tested them all on multiple test patches and the speculation based on my experience isn’t correct.
 
The following is a cut and paste from another forum, credit to Chet who is a coil winder and has some interesting things to say about ML coils.
Possibly there are ways to run larger coils on the 6000, who knows? My experience withe the current largest coil does not match up to this.


GPX 6000 test coils

I know of some areas that have produced some large nuggets. So in pursuit of large gold I have experimented with winding some test coils and did some air testing. Results are with my poor hearing and varying EMI conditions. But the measurements work for my comparison testing. On bad EMI days the larger coils are very noisy. A 20 inch 12 AWG Litz coil might be the next one to test. Meanwhile I am experimenting with some large GPZ 7000 coils.
Have a good day,
Chet


Coil Description 1oz gold coin Air test inches
30" x 30" = 34"RND 1.86mm flat spiral Litz wire 27
24" x 24"= 27"RND 1.86mm flat spiral Litz wire 27
23" RND 2.3 mm 14T 3 vertical rows Litz wire 26
17.5" RND 2mm Litz, spiral flat wound ID 14" 22
17" RND Vertical Wound 2mm Litz wire 21
17" x 13" Minelab GPX 6000 coil flat spiral layers close wound 12 AWG Litz wire 18
11" Minelab GPX 6000 flat spiral layers close wound 12 AWG Litz wire 17
14" Minelab GPX 6000 DD Coil 14
6" GPX 6000 DIY flat spiral close wound 56 turns 2 layers 1.86mm Litz wire 11
 
Dunno Chets coin but most 1 oz gold coins are ~33mm dia ( ZA Krugerrand, AU Roo, US Eagle).

AUD 50C is 32mm AF & 75% Cu so reasonably comparable target.

Chet got 17in (425mm) for 11"ML coil & 14in (350mm) for 14"DD ML coil in air for 1oz coin

I got +550mm ( 11" ML coil) & ~450mm for 14" DD ML coil under slate for 50c so substantially better distance but directionally same ie 11" coil is substantially better than 14".

I was running max sensitivity settings ( Normal ground, Auto+ & Threshold on) on speaker.

https://www.prospectingaustralia.co...-ex-minelab-engineer.42049/page-2#post-676747

I would be very interested to see what a tuned 18" mono coil could do on the 6000, even if it drops some tiddlers.
 
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Dunno Chets coin but most 1 oz gold coins are ~33mm dia ( ZA Krugerrand, AU Roo, US Eagle).

AUD 50C is 32mm AF & 75% Cu so reasonably comparable target.

Chet got 17in (425mm) for 11"ML coil & 14in (350mm) for 14"DD ML coil in air for 1oz coin

I got +550mm ( 11" ML coil) & ~450mm for 14" DD ML coil under slate for 50c so substantially better.

I was running max sensitivity settings ( Normal ground, Auto+ & Threshold on) on speaker.

https://www.prospectingaustralia.co...-ex-minelab-engineer.42049/page-2#post-676747

I would be very interested to see what a tuned 18" coil could do on the 6000, even if it drops some tiddlers.
I only reposted his numbers, he also commented that the bigger coils get very noisy which is evident in the 17mL
They speculate (that word again) the noise is because the 6000 doesn’t run actively shielded coils. I don’t know as not an electronic guru but I would like a bigger coil
 
A few words to clarify my coil testing; the do it yourself coils are prototype transmit coils for the GPZ 7000. I tested them on the GPX 6000 (normal, auto 2, no threshold, with speaker) just to find out how they would do. Most are wound on foam board so that I can unwind and reuse some of the expensive Litz wire for the next experiment. They are not shielded so I have to take them out of town to test farther from EMI.

I just air tested indoors the US one ounce coin and a 1983 Australian 50 cent coin. The gold coin is approximately 1mm greater in diameter and thickness.

Using the GPX 6000 14” DD coil, Normal mode, with Speaker, indoors with high EMI;

Mode 1oz coin 50 cent coin

Auto 2 14” 16”

Auto 2
With threshold 16” 18”

It looks like the shape or metal difference gives the 50 cent piece a better distance. Also this is the first time comparing with Threshold, the 2” difference is a surprise for me.

The GPX 17” Mono and the GPX 14” DD transmit windings are both wound with 2.7mm Litz wire suspended in a plastic rack. The inside of the coil housing is shielded with approximate resistance of 50 ohms per inch. The shield wire runs as a separate wire through the coil cable into the control box to terminate on the printed circuit board.

The noise increase with larger coils is because of the increased sensitivity design for small gold. The larger coil is a larger EMI antenna for such a sensitive receiver design.

Have a good day,
Chet
 

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