Noisy EMI with GPX 5000

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Noisy EMI with GPX 5000

Post  hugh62 on Sun Mar 16, 2014 12:16 pm

G'day everyone 1st post so i'll see how i go , i'm a plant operator on a cattle station near MT ISA and started detecting when i bought my 1st detector  a 3500 not long after they came out ,then a xterra 70 and now the 5000 . And yes i have the dreaded GOLD FEVER !! Hopefully planning to prospect full time in the not to distant future !! Love the 5000 as most of my time has been spent in the NW QLD and central NT , where me and the 3500                 ( unmodified ) really struggled with the heavy minerilisation in certain areas . How ever i do find one flaw in particular with the 5000 and that when the temperture gets over 38-40 deg it's EMI gets a bit noisy ,in particular in the hills /ranges , where the minerilisation is very mild ,sandstone shale and by the shafts in the area is up to 40' deep ,no Ironstone, very little surface Quartz ,Schist etc,and no power lines etc . Manuel tunning doesn't seem to help much , nor using a mono or dd coil ,control box has cover on it . Useing a 6'' coil on FP runs brilliantly , 11'' coil starts to get a bit noisy noisy under those extreme temps . However a few weeks ago after some good rain ,i went back out into those hills while  it was still wet ,and the temperature was mild  28-30 etc , the detector worked beatifully, even using a 18/12 mono my favourite coil !! Out of the hills and on the slopes and flats even under extreme temperatures  and heavy minerilisation i can get the detector to run smoothly  even with a 18/12 coil mono but on FP only !! I've noticed on this forum and others that this is a bit of a problem with the 5000 ( temperature wise ) I might add i do really love to run a smooth threeshhold if possible , as this is what i really love about this machine ,it's ability to run quietly , Fine Gold/special etc . So apart from stating the obvious ,wait for cooler temperatures , maybe a 8'' coil ?? signal booster ?? The gold is very fine / micro etc and in very fine Quartz veins sometimes and at 1'' - 6'' depth . Welcome any suggestions , cheers for now .  V11 V56
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Re: Noisy EMI with GPX 5000

Post  kon61 on Sun Mar 16, 2014 5:56 pm

Welcome to the forum Hugh.

      Your on the right track by the sound of it.Fine gold,small coils.Not much different to here in Vic.Hot northerly winds with elevated temperatures raise both ground noise as well as carry EMI over the hills.The cooler days are the way to go.Signal booster on a 5000,what for?  You state little mineralization,shallow depth and fine gold to be found? You might just get better results by using a high frequency VLF such that of a Gold Bug 2 or a Whites GMT coupled to their smaller coils? Anyway's,the smaller the coil on the 5000,the better your chances of picking up the finer gold.Also,(although mild ground conditions by the sound of it) if you do have within your possession any of the smaller DDs such that of 10x5s,do give them a good work-over?

      Cheers Kon.What a Face
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Re: Noisy EMI with GPX 5000

Post  pilbarachad on Sun Mar 16, 2014 10:58 pm

Hey mate,

We have the same EMI issues over here in the Pilbara this time of year with the constant high temps, basically all me and my mates do is run a small coil (8x6 sadie) which you have already sussed out. Also heading out real early in the morn and finishing up before lunch means that you will avoid the worst part of the day.

Personally i cant wait for it to cool down up here  Very Happy Very Happy 

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Re: Noisy EMI with GPX 5000

Post  Wombat on Mon Mar 17, 2014 9:10 am

Hi Hugh62 and welcome to the site mate. As what Kon61 said, we have the same EMI trouble here in the Golden Triangle in Victoria. I live in the triangle and spend a lot of time out in the goldfields. In one area that I work I get a lot of EMI so I rang the Technical Boys at Minelab to see if they could give me some idea on how to handle the EMI. And this is what they told me to try :-
(1) Turn your Gain & Stabilizer to maximum. (2) Motion Fast & then hit Auto tune button. (3) After Auto tune, set settings at RX gain 8 & Stabilizer 10, Motion very slow, Audio -Boost.
I have tried this and it seetles down the EMI a bit but not completely. Give it a try, you have nothing to loose.
wombat Wink 
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Re: Noisy EMI with GPX 5000

Post  Qld Sandy on Mon Mar 17, 2014 6:25 pm

Wombat wrote:Hi Hugh62 and welcome to the site mate. As what Kon61 said, we have the same EMI trouble here in the Golden Triangle in Victoria. I live in the triangle and spend a lot of time out in the goldfields. In one area that I work I get a lot of EMI so I rang the Technical Boys at Minelab to see if they could give me some idea on how to handle the EMI. And this is what they told me to try :-
(1) Turn your Gain & Stabilizer to maximum. (2) Motion Fast & then hit Auto tune button. (3) After Auto tune, set settings at RX gain 8 & Stabilizer 10, Motion very slow, Audio -Boost.
I have tried this and it seetles down the EMI a bit but not completely. Give it a try, you have nothing to loose.
wombat Wink 

If you lose the BOOST audio and use normal you'll find it runs better, or go another step and use Quiet audio you'll find you can lift the stabiliser up to 14 or more and the gain around the same, depending on the coil selection of course.
Cheers.
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Re: Noisy EMI with GPX 5000

Post  pilbarachad on Mon Mar 17, 2014 11:01 pm

Good tips there Wombat and Qld sandy- im gonna try that this weekend and see how it goes.  Very Happy 

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