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GPX Coil Opinion Request


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11 hours ago, fredmason said:

be sure to check the ground before you place your test objects or your results will be totally confused...The yard in the city is about the worst place you could field test a Pi...especially a Minelab.

fred

Thanks Fred.  I totally agree with both statements.  Fortunately I don't live in the city but I did learn that the worst place it do a test with with a Minelab PI in the country other than in the house is on your deck or porch where I had previously tried to air test a mine.  Still too much EMI and Minelab PI's don't air test well anyway.  

As for my test garden, I put it as far from the house as I could (40 yards) which made a world of difference with reducing the EMI.  As to checking the ground for objects, I was hoping that wouldn't take me too long but I spent most of the entire day digging up a myriad of objects from the ground, unfortunately none of which had any value.  My goal was to just dig up objects within a couple of feet of each of the holes I dug for the targets.  I started out using the 3030 to dig the junk then switched to the Eureka gold as I had a little coil on it and figured it would pin point easier and it did.  After digging lots of targets and thinking I was near done I pulled out the 5000 and found another bunch of junk targets. If Minelab could only make a little nugget sound as loud as those little pieces of rusty iron it would be really hard to miss a finding a nugget.  Fortunately I'm near done with clearing away junk.  I managed to bury most of my targets today so by tomorrow evening I should have a report back to you all.  Digging the junk was a chore for sure but a good experience as I have very little time on the 5000 or the Eureka. But I will get some good training from Gerry in July in Oregon.  

Terry

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In case no one has mentioned this, you may have to push the tune button again after the machine warms up or the weather conditions change...places like Gold basin were better when i did this...just one more thing to keep under your hat...

fred

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4 hours ago, fredmason said:

In case no one has mentioned this, you may have to push the tune button again after the machine warms up or the weather conditions change...places like Gold basin were better when i did this...just one more thing to keep under your hat...

Thanks Fred, I'll keep that in mind, if I can.

Not a good day for playing with my 5000. I think it was a combination of the very mineralized ground I have, the heat and the EMI .  I wonder if there is a such thing as the EMI getting worse in the evening?  Seemed like that happen to me anyway.  Plus I was trying to test larger and larger Mono coils which probably increased the EMI as well.  The other problem with the larger coils is that I started to discover more junk that I had failed to dig up near my test holes with the bigger coils so my test garden is still a work in progress. Of course my unfamiliarity with the 5000 didn't help either.  To combat the EMI I tried turning some things down.  Using the Deep switch really increased the EMI so I could not use that mode at all.  

However through it all was able to compare the 14X9 Nuggetfinder Evo coil to the 8" round mono Minelab coil.

I used a 1 gram nugget at 5" and another 1 grammer at 7".  Two, (.2) gram nuggets, 1 at 5" and 1 at 4". and also a .1 gram nugget at 3.5".  Probably not much of a test in mild ground but in this ground none of the coils were hitting the targets really strong. But the 14X9 had the edge on all the nuggets except the .1 gram nugget and the 8" coil was a little louder on that one.  

That's all I'm likely to do with my test garden with the 5000 till I get back from my trip.  But if I get my wife's Honey do list completed soon I may take the Eureka gold out and try it out on the targets in place as there are no major EMI issues with it and it's much simpler to operate.  I do want to if nothing else, compare the Coiltek 6" coil for the Eureka to the stock elliptical coil.  I'm wondering which is the most sensitive etc. and by how much.  

Terry 

   

 

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What are you running your stabilizer at? Might stabilize it some more if you are in or near cities.

EMI does change in some places by time of day. Some interference can come from far off and be more intense at closer to night, like why AM radio stations have to reduce their broadcast power at night because propagation increases due to interactions with the ionosphere. Noise of certain frequencies also increases propagation distance and so in some places you'll start hearing a lot more in the evening.

Thanks for the test with the 14x9 and 8", good to know. A 14x9 hitting a .1 gram nugget at 3.5" in bad ground is pretty impressive really, even if it was outperformed by the 8", you can cover almost twice the ground..

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4 hours ago, jasong said:

What are you running your stabilizer at? Might stabilize it some more if you are in or near cities.

I was running the Stablizer very low most of the time.  Often at 1 or a high of 5. For whatever reason, to my ear, the EMI seemed to lesson with turning the stabilizer lower.  It also got lower with turning other things down but unfortunately I think the signal level also got lower.  I probably should have tested my DD coils in cancel when the EMI went higher but I didn't think to at the time. 

I was doing a little search on coils and came across this post which seemed like good general info from folks testing coils down under.

Terry

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4 hours ago, jasong said:

What are you running your stabilizer at? Might stabilize it some more if you are in or near cities.

I was running the Stablizer very low most of the time.  Often at 1 or a high of 5. For whatever reason, to my ear, the EMI seemed to lesson with turning the stabilizer lower.  It also got lower with turning other things down but unfortunately I think the signal level also got lower.  I probably should have tested my DD coils in cancel when the EMI went higher but I didn't think to at the time. 

Again this ground maybe the worst I have ever hunted on.  It's full of little hot rocks that stick to my pick when ever I dig here.  When I was trying to do an air test using the 5000 and the 14X9 Evo I tried waving one of the hot rocks that had stuck to the pick magnet in front of the coil.  It would detect it close to the coil but of course when you ground balance it to the actual hot ground it balances those out but at the same time I figure it's desensitizing the detector/coil as well.  This makes me feel like the 14X9 is a really sensitive coil but can be no more sensitive than the detector/ground conditions/EMI allows it to be.  

I was doing a little search on coils and came across this link which seemed like good general info from folks testing coils down under.

http://golddetecting.4umer.net/t398-testing-coils-mono-and-dd

 

I added this link as an Edit.  It is a very old post but the basics of the coil for a SD, GP or GPX is the same today as it was back when.  The GP and GPX however give the detector a little more adjustment for depth and or sensitivity. Most of you know this already but some may not and for myself being older and getting back to detecting it's a good review. 

http://www.docsdetecting.com/docsplace/jlange/confusion.html

 

Terry

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  • 2 months later...
On June 28, 2016 at 0:31 AM, jasong said:

What are you running your stabilizer at? Might stabilize it some more if you are in or near cities.

EMI does change in some places by time of day. Some interference can come from far off and be more intense at closer to night, like why AM radio stations have to reduce their broadcast power at night because propagation increases due to interactions with the ionosphere. Noise of certain frequencies also increases propagation distance and so in some places you'll start hearing a lot more in the evening.

Thanks for the test with the 14x9 and 8", good to know. A 14x9 hitting a .1 gram nugget at 3.5" in bad ground is pretty impressive really, even if it was outperformed by the 8", you can cover almost twice the ground..

 

I noticed that in the evening I hear less noise.

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As has been discussed you do not want to run your stabilizer too low ....below 7.  You will lose smaller targets when you do.

I would suggest that you read the manual, then re read it. If you are trying to test in the city it won't work. Too much EMI.

If you are out in the boonies and still can't get a stable threshold start by lowering the gain. I can run near those huge power lines and obtain a stable threshold with my stabilizer at 9 with a 14x9 coil. Check your other settings first.

 

Dean

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  • 1 year later...
On 9/17/2016 at 12:52 PM, bado1 said:

As has been discussed you do not want to run your stabilizer too low ....below 7.  You will lose smaller targets when you do.

I would suggest that you read the manual, then re read it. If you are trying to test in the city it won't work. Too much EMI.

If you are out in the boonies and still can't get a stable threshold start by lowering the gain. I can run near those huge power lines and obtain a stable threshold with my stabilizer at 9 with a 14x9 coil. Check your other settings first.

Dean

Thread recovery! Just had to bring this back up. What Dean says is spot on. Especially on the new generation of spiral wind coils, you don't want to overcook your Rx Gain. 

Smaller coils, and lower Rx Gain are you two best combats against EMI. Oh, and the old DD coil that most seem to have abandoned :cool:

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