Discriminator?

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Discriminator? Empty Discriminator?

Post  Nuggsy on Wed Feb 29, 2012 9:37 am

Just wanted to hear peoples thoughts on the discriminator function on Minelabs for example a gp extreme.
Seems to work well on small nuggets but wanted to know how well it would work on large finds. Anyhelp would be appreciated Smile

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Post  CostasDee on Wed Feb 29, 2012 10:17 am

Hi Nuggsy,
I use an SD2200d with DD coils and I always use the discriminator at about the 80% mark. I know people say not to use it and that it's unreliable and that you will miss gold, but I do always have it on and cautiously walk away from something that totally overblows the detector. I saves me wasting alot of time digging or scraping rubbish.
Know though that the discriminator will only work for about 3 inches, so you may pick up a signal and think its ok and start digging and it's only when you get within 3" that it will discriminate. By that stage I usually dig it out anyway as I've commited to 90% of the dig anyway.
Cheers.....
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Post  Guest on Wed Feb 29, 2012 1:27 pm

Gday Nuggsy,
Im no expert mate,but I will tell you a few of my past experiences.
Years ago with the SD2000-2100 you just had to dig everything. These detectors had no discriminators.
When I moved up to the SD2200d,I ran a DD coil and saved alot of time,but left alot of Gold behind.
One day in particular is lodged in my memory. My 2 detecting mates had just traded up to the GP Extreme,and were running Coiltek 10" Elliptical monos while I was swinging a Coiltek 10" elliptical DD on my 2200. The Ground we were detecting had some very hot pockets of Mineralisation,along with mineralised Slate but also some patches of quiet Pipe Clay.
They were killing it in the Virgin ground,while I was struggling for a few tiny bits I got on the Mullock heaps. My detector was running smooth and theirs were abit noisy. Some may say the difference here was the GP extreme V`s the 2200d was the extremes were a way better detector for small Gold. True,but the thing that was holding me back that day was my use of the DD.I switched over to my 10" Mono and started to get small bits in the Virgin ground as well. My detector was running with more ground noise,and I had to dig more junk,but the coil was more sensitive.

Another place,another time.
I was taken to some diggings on a flat that had been surfaced by the early diggers. They had left a few large areas between the surfacings(Maybe thats where their tents and shacks were) and there was a fair amount of Junk about. XL nails everywhere!
My detecting mates started off well,one finding a 20grm chunk close to the car,the other a 8 grm nugget on a little down slope from the remains of an old shack.Both were avoiding one patch of ground in the middle as it was Nail city. Lets say I was running a DD on my Extreme that day; I would have walked into this patch,discriminated all the targets and kept walking.
Lucky for me Im a sucker for punishment. I was running an old white Nuggetfinder 14" elliptical mono and started to clear this spot of junk targets. After about 45 mins I had them all and turned around to re-check my handy work. Right in the middle of the worst spot I got a faint signal,dug down 12 inches and scored a sweet 7 grm nugget. I then walked over to where my other mate got the 8 grm nugget and there was big trash everywhere.
After an hr of digging bits of heavy gauge wire,big nails and boot tacks I dug out a rusty spring from about 14 inches.Was just about to pull the pin and refill that hole when i rechecked the hole. Another signal in there (i was sure it was part 2 or the spring as it was loud) dug it out,and got a shock when a shiny 9.5 grm bit hit my palm.
The moral of these stories is that Monos are more sensitive,and also I would have most likely walked away from all that gold if I was using a DD because the junk was masking the Gold.

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Post  deutran on Wed Feb 29, 2012 2:55 pm

The largest gold taken from here during the last year that I'm aware of was 2.5 Ounce,found by a friend who detected some surface trash and removed it then rechecked the ground,it was only 6" down and found by a 2000 with an 11"mono.I could absolutely guarantee many coils had past over this in recent times and if using a discriminator would probably have missed it as well.
The tried and proven dig and check everthing works.A week ago I spent 3 hours clearing trash and detecting a new area digging a fair bit of deep trash like shotgun shells,chunks of steel etc.Just as I decided to call it a day got 1 last signal ended up a 5g speci that was a fairly weak signal on the 14 mono probably not detectable with an DD.
Nuggsy please be aware that gold can be discriminated out if it is very large near the coil or ironstone laden specs.
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Post  Nuggsy on Wed Feb 29, 2012 10:41 pm

Thanks for the stories and help guys! You have really opened my eyes up, all that info has givin me alot to think about.

I have been using the discriminator ever since I found my first piece and ran it over the coil whilst in Disc mode. Being lazy and wanting to save my ears from some of those ear piercing pieces of junk, I figured it must work... Probably why I have only found four small pieces. I was so sure I was onto a good spot when I found the last two as the area looked untouched by detectors and being that the nuggets were in a very obvious spot and only 1cm down if that. Will definatly be returning asap without the discriminator. Who ever said gold detecting was easy anyway Rolling Eyes lol!

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Post  Guest on Thu Mar 01, 2012 7:36 am

Gday

The only detectors I have used with reasonably accurate and reliable descrimination are vlf machines, all the pi machines do not have very unreliable descrimination, the only time I used descrimination was on my gp 3500, with the standard 11" dd coil, set on pseudo mono, the descrimination still worked to a degree.

It was only used on spots where it was littered with very small bits of rusty tin that were mostly on the surface, you can perservere with it in these situations if you know that the area is also littered with small shallow nuggets,but its hit and miss at best.

When using the descrimination you will find that it is also depth limited, and a buried ferrous target will give you a signal, and then when you start to dig it and get closer to it the descrimination will start to function and the signal will break up, so really a lot of times you have already had to dig the target so you may as well go all the way and get it out.

Remembering that also if there is gold in the area, ferrous trash can mask a nuggets signal, once the trash is removed other signals can be heard, its always wise to swing the coil back over the hole and what you have dug out of the hole just to be sure, this even goes for when you have taken a nugget out of the hole as very often there can be another piece in the hole and sometimes there may be several.

Dont fall into the trap of relying on the descrimination, follow the tried and tested method, "dig everything", many detectorists including myself can recount the times when they could have walked away from a nugget due to an odd or iffy signal, only to find they have decided to dig it up they have scored a nugget, or have walked away and someone else has dug it up for them.

cheers

stayyerAU




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Post  Nuggsy on Thu Mar 01, 2012 8:21 am

Thanks StayyerAU, I definatly wont be relying on the disc function anymore. If the weather clears up today im going to head out and try my luck Smile

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Post  kon61 on Thu Mar 01, 2012 8:37 pm

G'day guys

Ask yourselves this.Is not the discriminator on the Minelab pulse machines designed to work reasonably well to within the 4 inch mark? If I had spent half an hour digging a 2 foot deep hole for a positive signal,even though I fear digging deep holes,would it not be in my interest,that after going 20 inches down,not to go the extra 4 in order to distinguish clearly what the target is,or do I walk away not fully knowing what it ever was,as I have done on more than one occasion in the past,because an unreliable discriminator told me so? Even the saying "when in doubt,dig it out" is not good enough considering some of my multy ounce finds not only sounded like junk iron targets,but actually fooled the discriminator to blanking them out,the closer I got to the target. As for junk near the surface or within the 4 inch depth mark,well,half a dozen swings of the pick,aint to much to ask for in order for you to visually reach inspection of the target,before walking away.

Cheers guys.kon61.
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Post  Guest on Fri Mar 02, 2012 9:33 am

Gday

I might also add that it was one of the first pieces of advice I was given by an old hand detectorist, never walk away from a buried target, even if you dig up rubbish and theres still a signal there make sure you find out what it is.

I have told this story before, this reply was in response to me telling him that theres a lot of rubbish where I was detecting, in the very same area he happened apon an open detector hole, with an old coke can standing at the side of it, running his coil over the hole there was another signal, another can he though and almost walked away from it, then decided to dig it anyway, what he got was a 7+ ounce specie, buried a bit further down, the original detectorist had fallen for the same thing thinking more junk, and simply walked away.

Always remembering this, it is very rare that I will walk away from anything that I have not identified, and now dont ever use the descrimination for that reason, if you dig it up and its junk then you know one way or another and you can forget about it and move on, but if you dont then sometimes it will play on your mind, having you wondering at a later date what if it was gold?, its far worse when you have memories of something like this and cant re locate the exact spot again.

cheers

stayyerAU


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Post  Nightjar on Fri Mar 02, 2012 10:15 am

Tried using the discriminator years ago and soon found gold was being left behind.
If you are a treasure hunter maybe it is helpful, out on the goldfields forget it.
We will never know, however last year a mate of mine checked a large deep hole someone had left open and walked away.
100mm further down out came a specimen, riddled with gold.
How could this have been left after already digging a hole about 400mm deep?

Peter
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Post  Guest on Fri Mar 02, 2012 12:15 pm

Too true Nightjar,
If your going to dig a whopper of a hole to start with,you might as well get the target out. If the day is a warm one,or its the first target of the day,just leave it for an hr and come back to it later.
I have dug some huge holes over the years. Deepest was close to 3 ft and took 2 hrs for a big chunk of Brass Plate Rolling Eyes

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Post  Nuggsy on Sun Mar 04, 2012 9:16 pm

You guys have definatly conviced me Smile

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