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Nox 800 Vs Emi


Horst

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Friends,

I have been hunting with my new Nox 800 for the last 5 months now on a nearly daily basis. I found a bunch of very interesting stuff and coins.

There is a VERY interesting field right where I live. I know the area has been populated for several hundreds of years and that field is very close to even old houses. A hot spot from my point of view. Unfortunately a high voltage overland electric lines cross right over the middle of the field. I get so much EMI that the field cannot be worked Grrrr..........

Does anybody have a good idea? I went through the available channels manually and auto but still too much EMI. Reducing the gain doesn't do the trick!

Any more suggestions from your side?

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Try using a single frequency instead of multi....I've had to do this in a couple of spots while working in town.

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I have hunted many sites that exhibit harsh EMI on the Equinox.  At these sites, if after performing a noise cancel in the conventional way and not seeing good results, I'll lay the coil flat on a clean ground area and do a noise cancel.  If at that point the machine doesn't quieten down to my satisfaction I'll listen to each channel and pick the one with the least "noticeable" EMI.  Now, If I'm still not happy I'll reduce the sensitivity a couple numbers at a time.   

Final note, in most cases, as long as the coil is in motion the machine will run quiet but when I stop to dig a target the EMI will ramp up.  I know this is not a documented noise cancel procedure, but it works.  Give it a try.  Don't get frustrated and give up. 

 

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A couple of weeks ago I was hunting a permission that has persistent, harsh EMI. All of my typical tricks failed to reduce noise sufficiently to hunt. I went through multiple noise cancels, sensitivity reduction, single frequencies, factory reset, etc. What finally reduced the interference enough for me to hunt was to switch from my 11-inch coil to my 6-inch coil. The machine still had some interference, but it was manageable through the techniques mentioned previously in this thread.

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After noise cancel reducing gain has a dramatic effect on EMI. The lowest I have had to run is 14. Most people refuse to reduce gain that low.

Another thing to watch... are you hunting in all metal, no target id numbers blocked? Most EMI comes in at certain low range numbers. Simply blocking the offending numbers will quiet things down.

It starts where it starts though and different modes have differing EMI sensitivity. If Field 2, for example, is too noisy, try Field 1 instead.

Interesting to me is that high recovery speeds tend to enhance EMI by putting a sharper edge on the noise. Settings of 6 and higher are extra noisy, try 5 or 4 instead.

As has been mentioned going to single frequency combined with the above notes will almost always solve an EMI issue. Use the Gain setting as your guide. I would rather run a single frequency at Gain 21 than in Multi at Gain 14 for instance. Every time you try an option, see how high the gain can go before things get too noisy.

I love the last post... people tend to forget small coils almost always work better in high EMI locations. It is literally a reason to own one.

 

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Hi,

everything that has been said before has worked for me.  I have had to turn sensitivity/gain down to 8 or 10 in a few places here in the Denver area. Even in the moderate to high mineralization and EMI here, the Nox will still hit 6" to 8" coin sized targets with ease. Some other detectors I've used at these sites made by FTP, Tesoro, Whites and Garrett could not cope with the EMI plus high mineralization and were unusable.

 

Jeff 

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thank's guys that's the kind of input I was hoping for. I reduced gain to 10 and it was too noisy. But.....I have a 6" coil waiting for me in California. When I go over in September I will bring it back to Germany. I am positive the field will still be there!  I am using Field 1 most of the times. I will play around with the programs and see what happens. Recovery speed is a very good suggestion too. I usually run it at 6 and will try to lower it. I usually hunt in all metal 2-tone.

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I live in the bay area and have been hunting a few spots lately near busy roads and power lines...last couple weeks i've been hunting in a strip of dirt that has regular telephone pole power lines right over me ....a chain link fence 3 feet away and then 20 feet away on the other side of the fence High voltage power lines. Like Mark does I do the noise cancel with coil on the ground and then reduce the sensitivity.  I've been able to run it at 18 no problem...I've learned to put up with chatter if I want to hunt these small areas...another thing I figure is that most detectorists will shy away from hard to hunt areas and I'll find stuff here. 

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