Making a better coil for minelabs?

[Nova]

After perusing this forum for quite some time i have come across the statement that minelabs require strict measurements like for example 300uH on the TX etc... , now; after knowing that how is it possible like ( Nugget finder, Coiltek , X coils (russian brand)) to create supposedly better (deeper and more sensitive) coils than what minelab themselves create?. If the measurement requirements are strict then how or by what magic can these companies supposedly create a superior product, what am i missing here?

On another note; let's say that a person can create a better coil , in respect to mono coils is there a resistance and or inductance value away from the 300 standard that will increase the depth on a large coil? and if there is, what side effects will this create like ( more noise in highly mineralised ground etc...)

And one more, what coil would be quieter on a SD2200d mono or concentric?, i have the option of buying a 24in concentric , but if i could make a 32-36in mono and get much better results well then.... and i am talking about Victorian goldfields soil highly mineralised in places.

Hope for some good honest responses from you guys!!

[Carl-NC]

My understanding is that a coil which is otherwise identical to a ML coil, but has a higher resistance, does not perform as well. Can other parametrics be changed for improved performance? Maybe. But I wonder whether the aftermarket coils really work better, or are they simply different sizes that ML does not make. I expect if you measure the coil parametrics they will be very much in line with those of a stock ML coil. The place for improvement might be in an IB coil where you have more leeway on the RX coil. Otherwise, moving too far away from the expected parametrics will likely require circuit changes.

On the SD2200, I would think the concentric will be quieter since the RX coil is (likely) smaller and will have less ground pickup. However, if this is an IB coil then lift-off effects are certain to be worse.

[Elliot]

Nugget Finder recently came out with some new coils for the Minelab Equinox (VLF or CW) series. Their marketing arm were spouting claims of "better depth" and "greater sensitivity" just as you mentioned. When I challenged them to prove these claims, they admitted that they were simply comparing performance advantages due to to just coil size! For example, a smaller coil will be more sensitive, and a larger coil will go deeper. Their claims are misleading for the unwary, as there are trade-offs for greater sensitivity (i.e. loss of depth), and greater depth (i.e. loss of sensitivity), but they are happy to not spout the trade-offs of course. Regarding mono coils for Minelab's pi machines, Nugget Finder do make great coils that match the inductance and resistance specifications, but they also happen to make coils of lower capacitance (using flat wound Litz wire), which can increase depth and sensitivity IF the machine can be adapted to take advantage of lower capacitance coils - which is a separate question.

[ozgold]

After perusing this forum for quite some time i have come across the statement that minelabs require strict measurements like for example 300uH on the TX etc... , now; after knowing that how is it possible like ( Nugget finder, Coiltek , X coils (russian brand)) to create supposedly better (deeper and more sensitive) coils than what minelab themselves create?. If the measurement requirements are strict then how or by what magic can these companies supposedly create a superior product, what am i missing here?

On another note; let's say that a person can create a better coil , in respect to mono coils is there a resistance and or inductance value away from the 300 standard that will increase the depth on a large coil? and if there is, what side effects will this create like ( more noise in highly mineralised ground etc...)

And one more, what coil would be quieter on a SD2200d mono or concentric?, i have the option of buying a 24in concentric , but if i could make a 32-36in mono and get much better results well then.... and i am talking about Victorian goldfields soil highly mineralised in places.

Hope for some good honest responses from you guys!!

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Hi Nova.

Yes you can improve the depth and run higher settings on a GPX. Mono self made coil. The GPX. 45/5000 models will run a higher uH, up to say, 370uH + with-out problems.

But the best area of improvement to aim for, is around the 325 to 330uH, where in average ground in Victoria, you can now run in Normal Timing.

With the SD 2200d, like Carl said, aim for the Concentric coil, more so than a noisy mono.

Cheers ozgold

[Nova]

Great stuff guys, thanks for the honest and to the point answers, i recently bought a 5000 have detected 5 days in Mt Crawford (Adelaide area South Australia)(for bullets and rust, last time out just the other day, found 2 bits of ironstone one with a bit of quartz( but no visible gold) will smash em on the weekend to see if anything. Question : running the 5000 in general/normal is it well known in this settings to hitting hotrocks?, i have experimented with practicly all the timings and have found junk with all of em, i think Nenad has cleaned the place up ( one of the locals who has detected the place for years), will have to hit Victoria soon or will go crazy just digging rubbish all the time.
One more for you guys? i have an old Coiltek 24in DD and i can buy a Detech 24in Concentric, now presumably which one could i expect to be of more benefit depth wise in highly mineralised soils with either the SD or the GPX?

[ozgold]

Great stuff guys, thanks for the honest and to the point answers, i recently bought a 5000 have detected 5 days in Mt Crawford (Adelaide area South Australia)(for bullets and rust, last time out just the other day, found 2 bits of ironstone one with a bit of quartz( but no visible gold) will smash em on the weekend to see if anything. Question : running the 5000 in general/normal is it well known in this settings to hitting hotrocks?, i have experimented with practicly all the timings and have found junk with all of em, i think Nenad has cleaned the place up ( one of the locals who has detected the place for years), will have to hit Victoria soon or will go crazy just digging rubbish all the time.
One more for you guys? i have an old Coiltek 24in DD and i can buy a Detech 24in Concentric, now presumably which one could i expect to be of more benefit depth wise in highly mineralised soils with either the SD or the GPX?

Hello Nova.

I think you could improve your settings for the 5000 to help you.

As far as the Coils, the SD 2200 with an old 24"DD coil, works well. I have seen some big deep nuggets pulled out of the mineralised Vic goldfields with that combo.

The CC col would be better used on the GPX 5000.

Good luck, ozgold.

[Mdtoday]

Great stuff guys, thanks for the honest and to the point answers, i recently bought a 5000 have detected 5 days in Mt Crawford (Adelaide area South Australia)(for bullets and rust, last time out just the other day, found 2 bits of ironstone one with a bit of quartz( but no visible gold) will smash em on the weekend to see if anything. Question : running the 5000 in general/normal is it well known in this settings to hitting hotrocks?, i have experimented with practicly all the timings and have found junk with all of em, i think Nenad has cleaned the place up ( one of the locals who has detected the place for years), will have to hit Victoria soon or will go crazy just digging rubbish all the time.
One more for you guys? i have an old Coiltek 24in DD and i can buy a Detech 24in Concentric, now presumably which one could i expect to be of more benefit depth wise in highly mineralised soils with either the SD or the GPX?

I'm not sure on your experience in prospecting or knowledge /history of the area but just a couple of notes from my experience in that particular area.
Most of the gold in the area you refer to was found at depth, (2 metres, way down to 60m in some places) with the exceptions of a few scattered sections in a small number of gullies. Everything else is on private land.
Large coils in this area are pretty much a waste of time IMHO. Try a small 10 x 6 Sadie or similar if you haven't already
Some people want you to think it's all flogged out, It's not!
Sure they are sub grammers, still gold though.
You will find a spot in the Mt Crawford area that will give up some yellow but you will have to dig a lot of junk.
The worst thing about MT Crawford is that very few people fill in their holes. The more they do it, the more we get locked out.
I am taking it, that you have a year permit and gate lock code, if so, that's the area (quite steep).

Cheers

[Nova]

Ozgold, mate the 5000 is not as complicated as i thought it would be, i have researched the timings quite a bit and understand that what they are is different ground balance settings, and i also understand that deep/general etc... are PRESET settings and that's all they are, i believe it's better to run more to the hotter settings without getting the machine screaming and moaning too much, and i have been using a 14in mono have tried the 11in, the 24in is for Victoria only.
MDtoday, yeah i have done a reasonable amount of research on the area (Mt Crawford) and in particular Watts gully. It produced around 3300 ounces and had many 9-12 oz pieces, but when one looks at the diggings, one can clearly see that the gold was almost all dug from the very near bottom gutters and most of the holes would of been 5-7ft deep, obviously, what choice does one have then?, hit the mullock heaps (possibly 1000's have done that?) or hit the slopes and hope for a missed piece?
Yep; the very steep parts was exactly were i was and that's were i picked up these 2 pieces of ironstone. you have to think a little out of the box these days in particular smashed area's, but there is still gold there as i see Nenad post the occasional vid of a nugg he's found in the area.
I envy the remote operators some who are finding ounces a week, it kills the spirit walking over flogged grounds hoping for a speck, but for us south ozzies there not much of a choice, i am really pissed that so much potential land in S.A. is either private or no go national parks, i know there has been decent chunks found on some private grounds so it's definetly here just not accessible, so what can one do ( look for greener pastures i suppose!) .
Yep also; i do have the 5 x 10 dd coil was a bit lazy to put it on, probably should get me self a small mono, put the 5000 either into Sensitive Smooth or Fine Gold, and why do people almost exclusively use Fine on the 5?, like what is the point to have 7-8 timings and only use 1, i don't really get that, might as well then just use the SD or a GP for that matter, and you would be surprised at how small an item the SD can find, tried 18in DD a few weeks ago found a piece of brass at about 6-8 inches deep, was about equal in size to a 0.2 gram nugget, and the 14in mono have dug some very deep targets with it on the SD, just too many false signals on Victorian ground that's for sure.
Okay babbling on like an 80 year old granny LOL, over and out!!

[Mdtoday]

Nova,
I was out testing one of my PI designs not long ago in Watts Gully on a random mulluck heap.
Had the 10 x 6 on and picked up some tiny pieces by digging into the base and raking.
Couldnt pick them up with the larger 14 inch.
I agree about the way SA like to lock things up with regards prospecting ....sorry ?fossicking? of course we can?t sell what we find.
The Watts Gully area is so overgrown with Blackberries bushes and new undergrowth now where in the past they were a little more controlled and you could get into some good spots. The dark side of me says greenies like it this way

Cheers

[Nova]

Mdtoday, yep, the greenies have orgasm's when then see overgrown bush, probably the female one's even find the odd branch to rotate on to get their jollies LOL!!!
They look at the habitat and say the animals will love it, look; i am an animal lover, but; there is more than enough bush out there for them, no need to screw the human up for little to no reason, people have all sorts of religions and being a greenie is one of them, and raking is definetly something i have considered doing in particular certain areas of Victoria.
One more question for Ozgold?
You say that you have made better coils, by what method did you test these coils and by how many different brands did you test it against?
I believe the best way to test would be to make say an 11in mono then test against all possible other makes out there, and i would test it on a test bed with either real nuggets or lead coated rocks( that would resemble possible nugget shapes) is that how you did it?
I have read on this forum that flatwound is supposedly more sensitive and deeper that bundle wound, but then why didn't Minelab make their coils flatwound? i know Rowan at Nuggetfinder has developed a special way to wound his flats, at least that 's what it says on his website. I guess if flatwound really is better and lets say you get 2in extra depth, well; 2 inches is what you didn't have before so that's 2 inches of extra depth that will be searched and you will have an advantage.
So; basically what i am getting at is; to really know that a homemade coil is really better, extensive testing needs to be done to know for sure, people say yeah i'm finding more gold over old ground, but can one say for sure that they covered the area thoroughly?, how much EMI was there on previous occasions?, how wet was the ground last time etc..., many variables are at play, so really a very thorough testing system would need to be set up to know 100% for sure that you have a superior product??

[ozgold]

Ozgold, mate the 5000 is not as complicated as i thought it would be, i have researched the timings quite a bit and understand that what they are is different ground balance settings, and i also understand that deep/general etc... are PRESET settings and that's all they are, i believe it's better to run more to the hotter settings without getting the machine screaming and moaning too much, and i have been using a 14in mono have tried the 11in, the 24in is for Victoria only.
MDtoday, yeah i have done a reasonable amount of research on the area (Mt Crawford) and in particular Watts gully. It produced around 3300 ounces and had many 9-12 oz pieces, but when one looks at the diggings, one can clearly see that the gold was almost all dug from the very near bottom gutters and most of the holes would of been 5-7ft deep, obviously, what choice does one have then?, hit the mullock heaps (possibly 1000's have done that?) or hit the slopes and hope for a missed piece?
Yep; the very steep parts was exactly were i was and that's were i picked up these 2 pieces of ironstone. you have to think a little out of the box these days in particular smashed area's, but there is still gold there as i see Nenad post the occasional vid of a nugg he's found in the area.
I envy the remote operators some who are finding ounces a week, it kills the spirit walking over flogged grounds hoping for a speck, but for us south ozzies there not much of a choice, i am really pissed that so much potential land in S.A. is either private or no go national parks, i know there has been decent chunks found on some private grounds so it's definetly here just not accessible, so what can one do ( look for greener pastures i suppose!) .
Yep also; i do have the 5 x 10 dd coil was a bit lazy to put it on, probably should get me self a small mono, put the 5000 either into Sensitive Smooth or Fine Gold, and why do people almost exclusively use Fine on the 5?, like what is the point to have 7-8 timings and only use 1, i don't really get that, might as well then just use the SD or a GP for that matter, and you would be surprised at how small an item the SD can find, tried 18in DD a few weeks ago found a piece of brass at about 6-8 inches deep, was about equal in size to a 0.2 gram nugget, and the 14in mono have dug some very deep targets with it on the SD, just too many false signals on Victorian ground that's for sure.
Okay babbling on like an 80 year old granny LOL, over and out!!

Hello Nova.

Quote: Ozgold, mate the 5000 is not as complicated as I thought it would be, I have researched the timings quite a bit and understand that what they are, is different ground balance settings.
==============================
Nova, your comments on the settings and in running a GPX 5000, seem a bit simplistic to me. I have been detecting for over 40 years, and am still learning the multitude of combinations available on a 5000.
You seem confused on the aspects of Ground balance and Timings, plus talk about factory pre-sets.

There is a lot more to it than that, you speak on using hotter settings, but you must still get a balance of what to raise and what to lower, to run it in a manageable form, otherwise you will drive yourself nuts, and still miss out on finding gold.

You ask why most people use Fine-Gold timing exclusively with a 5000, well Nova, because it is one of the better Timings of this model. I think it is wrongly named, most think you use it to find only fine gold, but it has been proven on deep gold, it is perhaps the best deep timing too, sometimes even going deeper than Normal timing.

You may not think so, but the GPX series are miles ahead of the older SD series. I had all the M/Lab SD detectors, and for me the SD 2200 D was the best, the next step up for similar gold was the GPX 4500.

Yes, you are behind the 8-ball living in South Oz, it might pay to save up your detecting trips to only a few a year, and visit Vic. or W.A.

With your coil selection, the DD coils always suited the SD detectors, it was when the GPX models were released that the Mono coils came into their own, thanks to the Smooth timings.

Buying more coils is where you have to have a good think of what you are actually wanting out of detecting, meaning, are you happy to chase small gold, or do you want to find something of a decent size?

A small coil will not do the required job if looking for big deep gold, (Rule of thumb), they do not go much deeper than the width of the coil, that means an 18” or 20”in Mono is more suited on deep slugs in hot ground.

Quote: “You would be surprised at how small an item the SD can find”. Been there done that.!

One more question for Ozgold?


Quote: You have made better coils, what method did you test these coils with. Did you have a test bed with either real nuggets or lead coated rocks?

We had real nuggets big and small; in PVC pipes at different depths in a creek bank, these H/made coils were tested against all other brands of coils of the same size, this all done on the same detector using the same settings. Then repeating this on other model GPX detectors.

Quote: why didn't Minelab make their coils flat-wound?

I would think ease of manufacture at the time. The new GPX 6000 has flat-wound factory coils as standard.

Quote: that flat-wound is supposedly more sensitive and deeper that bundle wound ones.

Yes, the Flat-Wound coils are more sensitive, but more so on the receive signal. Whereas, the bundle wound TX coil punches deeper than a flat wound.

So, that is where a Concentric coil, is best made using a Bundled TX coil, with a separate Flat Wound RX winding.

Quote: So; basically, what I am getting at is; to know that a homemade coil is really better, extensive testing needs to be done to know for sure.

Making Coils, as you probably know is an art, and not to be taken lightly, it usually takes about half a dozen before you get the hang of it. Not to mention gleaning all the wealth of knowledge needed, from this very Forum, and all freely given. I thank all members here for your help, in getting me on my way to making coils.

Yes Nova, there are many conditions out in the field to make it hard to run your detector coil combination, and to aim for the best it can run on each particular day.

Most operators if not all have experienced this, you could write a book on these problems, and some have.

Cheers ozgold.
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[Nova]

Ozgold, good to see you did your extensive testing, maybe we both misunderstand what a timing really is, Carl; would you be kind enough to explain it to us in laymans terms?
I never said that i believe the SD series is a better overall detector, it has less timings for a start so that would not make sense, but it has proven itself on the big stuff over the years, will you deny that?
Once all the GP's and GPX's came out there was a distinct lack of big lumps being found, which shows how good a job the SD's did, and since many people stop using the SD's and bought the newer machines who knows how many more of the bigger chunks that were found with the GPX's could have also been hit with the SD's, i have dug at least 3 - 3ft holes for junk with it, so i know it hits deep on anything decent in size.
What is Deep/General/Custom ?, they are called modes but they are a PRESET SETTING or GROUPING of all the possible settings, many people get confused about what these modes actually are, and i assure you i am not one of them, read the bloody manual it is there in black and white, i'm sorry; but you just pissed me off with that.
I will give you an example; if you wack it into deep and adjust the RX and whatever else then this DEEP setting is no longer the preset but it is now your re-adjusted preset, so just maybe you have been using this machine for years without having a decent grip on it?

The Stabilizer as explained in the manual if set too close to 0 will filter out alot of signals, it would make sense to try and run the RX as close to 20 as possible would it not?. to hear those at the extreme range?. there is the argument that the machine needs to run as quite as possible, then there are those who say you need to run as hot as possible to get an advantage, since the machine has been out for many years and to get any advantage, how should it be run in you opinion? so; which is it then?