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Title: One for Chef......... Post by: waltonbasinman on November 03, 2011, 07:35:35 PM This applies basically to Minelab multi frequancy detectors Chef as I been trying to fathom this out for a while now. I basically keep getting tricked by a piece of really poor what I call wet Iron usually quite deep at about 8 - 10 inches and by wet I mean the clay around me when I get this signal is usually wetter clay than my normal dry crumbly clay which is the norm around here sat on top of Old Red Sandstone Bedrock. When I get this good signal It only disappears once the Iron is out of the hole. The ground up here has been really dry this summer and the problem has only really started with the coming large amounts of rain two / three weeks ago and has not happened before and the detector has no discrimination settings. Hope you understand this Geoff.
Title: Re: One for Chef......... Post by: Chef Geoff on November 04, 2011, 12:18:41 AM Ohh Eck! :-\ Give me the easy ones why don't you :D
Well the truth is that without being there I can't give an accurate answer, but there are few things that can cause it. When you say "you are being fooled", do you mean you are getting a positive reading and if so what numbers? All detectors can and do get fooled by large or circular pieces of iron this is down (allegedly) to the wrap around effect where the signal is so intensely conductive that it crosses over the ferrous/non ferrous barrier. Now add to this the improved conductivity gained in moist soil and this could explain some of the problems your having. Now here's one thing I have noticed which could be the same as you, especially as you mention "clay". The Polden Hills where most of my detecting takes place is an outcrop of Lias rock this is part of a band of Lias that stretches across the country and outcrops in certain places (worcester is one place, so Hereford could be another) and this is, in wetter areas, covered in a lias clay that is high in aluminium and iron (lias itself is an iron bearing rock) and I have found that at the onset of wet weather some fields become almost undetectable for several weeks, but by February this effect has dissipated. As to what is actually happening or why it lessens after months of rain I can't be certain but believe it's something to do with the machine almost being set with a hair trigger due to the GB and the iron being the better or easier signal tips the machine over the edge. So instead of blanking over iron many pieces start giving a positive signal. I know this doesn't help in solving the problem but rest assured your not alone ;D |