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GPX 6000 And Powerlines With Mono Coils


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6 hours ago, phrunt said:

they actually do work, I was surprised as I thought they might be a gimmick

Yeah they work well enuff but  coz they're open ended (for control & switch access), it was never gonna be a perfect fix. BUT, the 6000 has all the controls on the handgrip pad. So someone could make up full (perhaps folding) shield with just the coil input and speaker-battery sections open. It could make the 6000 an even better machine for EMI with the mono coils only....

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11 hours ago, strick said:

Sorry I was asking Ron with the 9" coil.. 🙂

This detector was received from the repair shop on 9/23/22 and has no issues with the external speaker.

The threshold being off causes a audio noise filter over the EMI allowing me to be able to hear the faint signals.

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16 hours ago, Aureous said:

 If the control box had a shield and not just graphite paint, it would add an extra level of noise reduction.

What about using some faraday fabric tape to cover the control box? I wonder if it would be of any benefit on the 6, or is all the "noise" coming in through the coil.

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You could wrap your control box in aluminum foil and find out, it's always best when connected to the floating ground though to get best results, not sure the easiest temporary way to do that, perhaps when screwing up your coil get a little bit of the foil screwed into the socket obviously nowhere near the wires as that could go badly, just in the thread.   I suspect most of the EMI is coming in from the coil and you can't do much about that, although it's why we are finding smaller coils working better in high EMI... smaller antenna.

The 10x5" actually works quite well in high EMI areas on the 6000, the NF 8.5x6 Z-Search will be pretty damn good when it comes out for EMI areas, looking forward to that coil.

I will try zero threshold next time, thanks for the tip Ron.  The 14" DD works well, it's just a bit awkward and not ideal in many places due to it's size.  It really makes the 6000 lose its weight advantage too.  Hopefully Coiltek come out with the small DD they've eluded to.

The 6000 surprised me with how good it works near power lines considering it's a GPX especially after the audio fix, it's not GPZ good but it does a pretty good job considering, even with the mono coils.

 

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4 hours ago, WesD said:

What about using some faraday fabric tape to cover the control box? I wonder if it would be of any benefit on the 6, or is all the "noise" coming in through the coil.

Wes, I'm sure any shielding would help but copper sheet is by far the best form of EMI shield. Its what is used on all medical devices nowadays. Faraday wire screen or wired tape is well worth a try, as is Aluminum. Flattened steel wool even works well! But copper sheet is easy to bend and you can apply black tape over it to avoid scratching.  A couple of elec engineers I've spoken to suggest that over 40% of the noise is absorbed via the oscillator and receive circuitry of PI detectors. The excellent aftermarket coils now available are very well shielded, compared to the stock 11 coil, so that alleviates a significant degree of noise there now. Just needs the control box covered now....

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I improved my T2's shielding by using extra layers of conductive shielding paint, painting the ground wire into the paint to secure rather than just the masking tape Teknetics used.  I did the same with my Gold Bug Pro which for some reason I can't find photos of but for it I added some copper tape instead and grounded it with a wire to the PCB's ground, it didn't have any shielding paint on it's plastic so obviously it didn't come with a shield wire to the housing.  It seemed to make a reasonable difference to both of them.  As with everything EMI it's hard to definitively tell if you made a difference but it sure felt like it did as I was able to run it in higher gain before I had problems.

IMG_20190513_092733.thumb.jpg.8a84e9e99a81f12b55793dd5f8f65ac0.jpg

Stock from factory, I'd already removed the shield wire which was masking taped onto the plastic housing in this photo.  It has a thin layer of conductive paint on the plastic from the factory which looked like it was sprayed on.

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A new thick layer of shielding paint just after being freshly painted.

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This is the paint I used.

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Shield wire back on after paints dried, the shield wire was painted on to hold it in place, don't know why I bothered putting the masking tape back on as I ended up putting hot glue over top anyway to hold it secure.

In saying all this, the conductive paint on the inside of the GPX 6000 shell is likely sufficient.  It handles powerline EMI much better than I expected it to.

foil tape.jpg

This is the copper tape I used on the Gold Bug Pro.

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54 minutes ago, phrunt said:

This is the copper tape I used on the Gold Bug Pro.

Hmmmm the copper tape idea is a good one, I forgot about that stuff. Used a lot on elec guitars..... I'll buy some and give that a go. I'll try single layer, dual layer etc.  <scratching chin> 

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23 hours ago, RONS DETECTORS MINELAB said:

The sensitivity was still fairly good and I was picking up the little bits pretty good. 

I know your capabilities Ron as we've hunted together a few times and will in the future.  But when mentioning your finds, please share a pic or two.  I'm still frozen in Idaho, so seeing some of your Au along with your read is tops.

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Back in the early 90s I used Nickel Shield Conductive Paint that came in a spray can. It worked good on coils that I made and repaired, as well as the crude PI that I made before commercial PI detectors hit the gold fields.

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