18" coil choice information and questions

Looking at adding an 18" round coil, for me GPX5000, to the arsenal. The largest I'm running, at the moment, is a 14X9 Coiltek Goldstalker mono.
And my main stomping grounds is in Vic's GT. Question is this: mono or DD? I'm working ground were I've pulled a number of sub-grammers and up
to a 1.5g, and want to have a 'deeper' gander. The ground's fairly mineralised and has it's share of the usual junk.

My 2 bobs worth is;
If you have a patch you want extra depth for larger nuggets, then go Mono.

However, if you are in an area new to you, then a DD will cover more ground quicker and be smoother in noisy ground, plus you can discriminate.

My largest coil is a 18x12 Mono, which, is in area equal to a bit over 14" dia. I have a 8" & the OEM 11" Monos as well.

The only DD I have is the OEM 11", so I have been deliberating the same question and have decided that as I can only afford the one, a bigger DD is more beneficial to me. So the question I ask myself is, a 14" DD or an 18". Given the scrub we find in Vic and that the 18" is heavier, I'm thinking the 14" would be easier to use and if I can't find it with a 14", I doubt I would with the 18".

I would think the 18" is more suited to open ground like in WA.

I'm new to the 5000, so others may have a different opinion.

Gedday there Mozzie .. Sounds like the 18" mono Nugget Finder is the coil for you! .. Lighter than the alternatives, Litz wired, and these buggers go deep .. Consider some experimentation with your settings and the NF may prove to be the most versatile coil in your arsenal.
Good Luck to you.

I can buy a new 18" IDL Spoked Tarantula Mono Coil (delivered) at a reasonable price I believe.

Been searching product and user reviews without much success. YouTube not showing many review examples either...

Anyone know this coil and even if not, have thoughts to comment on its merit or not?

Issues:

Is It Best To Seek Depth Due To Prevalence Of Already Worked Grounds?

Is This A Quality Product?

Seeking (Potential) Extra Depth Warranted And Does It Deliver?

Will The Loss Of Small Gold Sensitivity $$ Penalise Me?

This Open Spoke Style Coil Inviting Tangle and Hang Up (#+*^#!) Stress?

The Increase In Weight A Great Toll?

Cheers All And Happy New Years To You All...

Never used one but from what I can gather about them over the years is that they're about 50/50. 50% work well & 50% don't.
The fact they're no longer in business is usually a reasonable indicator?

PM Coils.

https://www.facebook.com/pm.coils/

https://www.youtube.com/watch?v=LW5PjYIU3oU

https://www.youtube.com/watch?v=0iA1fTrfFR8

https://www.youtube.com/watch?v=sPz64DNg7Ko

Steve where did you find the contact mate. Id be interested in one of those long thin coils

Happy New Year.

Hi nbasko, thanks for your concise reply.

This raises research questions for me of "50/50" in relation to quality. (quote - that they're about 50/50. 50% work well & 50% don't plus the company closed).

The YouTube vids I did see were the links that nesral has provided. I didn't think they were good or helpful for my research personally.

Tassie Daz, the facebook link above shows this phone number as contact - (03) 5358 3361 - half way down rhs.

or

http://www.gumtree.com.au/s-ad/staw...il-for-minelab-gpx-metal-detectors/1094706132

is the link that I persued by asking; "I read that your 18" tarantula mono coil advertisement is now somewhat aged, so I ask if you still have these available today? There is a history of offers received, please send an update". Thanks, Steven.

Reply; "Hi Steven, yes there are a few left. $120 incl post will get you one".

Sold 'as new' being ex shop stock it comes with 12 months warranty.

I am interested but perhaps I need more market referrals or user thoughts as per my original post.

Appreciate your help.
Cheers.

Yes i had one it worked for about 2 hours
they have gone broke so how are getting one?
just beware
Mond

Hi Mond.
Thank you.

They are found here;

http://www.gumtree.com.au/s-ad/stawell/ 1094706132

is the link that I persued by asking; "I read that your 18" tarantula mono coil advertisement is now somewhat aged, so I ask if you still have these available today? There is a history of offers received, please send an update". Thanks, Steven.

Reply; "Hi Steven, yes there are a few left. $120 incl post will get you one".

Sold 'as new' being ex shop stock it comes with 12 months warranty.

I use 3 of the PM coils all work well including the lovely slim 12x4" Nuggeteer.

Hi everyone,

So here's my first newbie question. My apologies if it seems stupid, but I'm having trouble getting my head around something.

Today I finally took delivery of a Minelab 18" DD Commander Coil. Certainly glad that I hung on to the harness as it's not until I held the coil in my hands and looked at it that I realized that it would be no stroll in the park having it swinging out in front of me all day.

Anyway, I'm sure I remember reading somewhere during my investigating about EMI and what it was, that a coil also transmits and receives out through the top to some degree as well as through the bottom (by all means please correct me if I'm wrong).

So, I'm thinking- What stops a large coil from picking up the lower shaft on the Minelab GPX5000 that I just bought? Of course it's metal, or is it that when I ground balance the 5000 takes this into consideration and adjusts accordingly? But then if this is the case and it does adjust for the metal shaft already there, am I then robbing myself of depth or targets the same size as my detector lower shaft because they have been effectively cancelled out?

Or, am I just overthinking the whole thing?

It's just that I have seen from time to time when researching getting my detector that some people have fibreglass lower shafts (I just assumed that they were trying to reduce weight), or do they do this so that there are no false signals etc from the metal shaft sitting above a large coil?

Thanks for any input,
Gary

No such thing as a stupid question , can only be stupid answers.

Hi Gary
Not a stupid question at all. Quite logical thinking in my opinion. Ive thought about this myself but dont have an answer for you; other than, perhaps because the shaft is fixed to the coil, and perhaps because its near vertical to the center of the coil, and that the coil and shaft are moving in unison, the shaft doesnt affect the transmit and receive magnetic fields.

I hope someone more knowledgeable than me can explain it. Id like to know too.

Cheers

Your GPX standard lower shaft should be non metallic I.e. a fibreglass type shaft?
Some people using larger coils will replace the stock upper shaft, which is aluminium, with a fiberglass or carbon fibre upper shaft. Normally the aluminium upper shaft won't pose a problem as it moves with the coil & is far enough away but when using 18-20" plus coils people have found there can be some effect on sensitivity with the detector compensating for the upper shaft.
When doing this they will usually also replace the standard non metallic lower shaft at the same time with the same brand lower shaft with the thought process of these fibreglass/carbon aftermarket shafts being lighter.

Deepseeker said:

.

So, I'm thinking- What stops a large coil from picking up the lower shaft on the Minelab GPX5000 that I just bought? Of course it's metal, or is it that when I ground balance the 5000 takes this into consideration and adjusts accordingly? But then if this is the case and it does adjust for the metal shaft already there, am I then robbing myself of depth or targets the same size as my detector lower shaft because they have been effectively cancelled out?

Or, am I just overthinking the whole thing?

It's just that I have seen from time to time when researching getting my detector that some people have fibreglass lower shafts (I just assumed that they were trying to reduce weight), or do they do this so that there are no false signals etc from the metal shaft sitting above a large coil?

Thanks for any input,
Gary

Click to expand...

The lower shaft is not made of metal (unless you bought a used unit and someone replaced the proper lower shaft with a metal one).

go CTX3030 style

carbon fibre

Nuggetbuster said:

The lower shaft is not made of metal (unless you bought a used unit and someone replaced the proper lower shaft with a metal one).

Click to expand...

Or unless it's a Chinese fake GPX maybe? :|

Thanks for all the replies folks,

Actually I think you're on the money Nuggetbuster. Since I last logged in I've been searching online for GPX5000 lower shafts, when it occurred to me to take my bottom shaft off and get something to scrape some of the end of the tube off where it goes into the upper shaft. To my surprise it scrapes off like it's some kind of hard plastic or fibreglass tubing. I was expecting to see the bare silver colour of steel or aluminium once I had scraped the paint off, but no, it remained all black. That surprised me as when i tapped it on the outside prior to my first posting it gave what I thought was a metallic sound.

I didn't for one moment think that I may be on to something that the engineers and scentists at Minelab had overlooked, it just didn't make sense to me how it could all work ok if the lower shaft was indeed metal.

Thanks for the feedback everyone!

The item that is metal is the wires in the cable coming from the coil, it doesnt detect this until it moves out of sink with the coil.
So you will get false signals when your cable is loose or is bumped or caught on grass, sticks, branches and the like.
Also when you move the angle of the coil on the shaft.
It really does surprise me how little false signals these things get.
Matt T