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| false signals in damp ground | |
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| Tweet Topic Started: Tuesday 27-04-2010, 06:04 (161 Views) | |
| captain101 | Tuesday 27-04-2010, 06:04 Post #1 |
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Good contributor
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Hi all went for a beep this weedend. Not much luck only 3 little bits but did notice something a bit wierd I was digging a lot of false signals with the 4500. While swinging I would get a good target response but after taking of about 50mm of dirt the signal would disappear. The surface layer was silty but under this was hard clay. As we had a bit of rain in the last week this clay layer was damp and the detector was picking up the silt. What I can't understand is why was the signal so sharp, normal ground noise is broader where the signals I was receiving where definite and both ways. There was no hot rocks and when the silt layer was spread out there was a response but very weak and you could not pin point anything. Has anyone encountered this before. If this is a common occurance its going to drive a few people mad as the signals are louder than small targets. Note the above was not site specific as I tryed 4 different locations and encounted the same problem at all of them. Captain. |
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| Nightjar | Tuesday 27-04-2010, 07:04 Post #2 |
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Contriibutor Extraordinare
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Morning Captain, This is a common phenomenon after soaking rain, the signal isn't actually coming from the top silt as you mention. If your pick breaks into and disturbs the damp clay pocket below the topsoil the signal almost disappears. Maybe one of the guru's can explain why these pockets sound off when damp? Cheers Peter |
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Good luck & safe travels Peter ![]() "Aging seems to be the only available way to live a long life." | |
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| thedigger | Tuesday 27-04-2010, 16:40 Post #3 |
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Contributor plus
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Having a electrical background,I would suggested that the moister lowers the resistance in the ground,and this gives you a low resistance spot like a target. |
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| beepinpete_WA | Tuesday 27-04-2010, 20:17 Post #4 |
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prospector
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Hi Captain maybe its where the iron saturated waters over many years accumulate in the lower sections of the underlying stiffer clays especially where the clay has a little divet or cup shaped depression, and so it could actually leave a "super" enriched iron type area where when it rains and becomes moist it acts almost like a small area of rusty metalic stuff.... Hence the loud & sharp signal reply until its broken up by the pick digging into it a bit. Just a thought. pete |
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| goldnomad | Tuesday 27-04-2010, 20:53 Post #5 |
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Contributor plus
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Captain, What settings and coil type/size were you using? It always helps when asking these sorts of questions to give as much detail as you can Robert |
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| captain101 | Wednesday 28-04-2010, 05:45 Post #6 |
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Good contributor
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Thanks for the reply guys. For your info I was running a 11'' mono and had the stabliser between 8-10 and the gain between 10-12 depending on the sites I was swinging at. Other settings are as per JP vid for small gold. regards Captain |
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| goldnomad | Wednesday 28-04-2010, 20:42 Post #7 |
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Contributor plus
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Try running the stabiliser down around 5 and the threshhold at barely audible. Don't worry, you're not gonna lose gold. I've run these settings now for some time and no longer have problems with clay domes or red clays. I still get the odd hotrock but they're on the surface anyway. One of the nuggets I picked up today was a 0.05 grammer using a 12" NF Advantage and the above settings. They work very well for me. Maybe not for you. Good luck Robert |
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| Jonathan Porter | Sunday 2-05-2010, 04:52 Post #8 |
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New contributor
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The problem could be caused my salt concentrations in the soils that are usually benign when the ground is dry. Try using a DD coil in Cancel mode, Tracking in fixed, Timings on Enhance and everything else the same way you would usually detect. It will also pay to invert the response as Cancel mode inverts things. Hope this helps, JP |
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| captain101 | Sunday 2-05-2010, 19:04 Post #9 |
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Good contributor
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Thanks again guys will try a salt coil instead of cancell, Gold nomad tryed your settings in a creek system with thick wash definity ran smoother the test piece I use (0.1gm) was still going off. cannot confirm how much punch I was getting as I didn,t get any targets. |
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8:42 AM Jul 11