Hi guys, Went out for a bit of a wonder over some old workings on Saturday. I had been over these with the 10 X 5 joey mono & the nugget Finder 12 X 7 mono & got gold with both coils. This time I used the 11" Minelab Commander mono that I have been using for a couple of weeks now on all my old haunts & still pulling gold off them with this coil.
Just goes to show you can still get gold off ground that has been gone over & worked with smaller coils by up sizing coil size slightly each time. The bigger coils getting better depth each size you use. So gold that was out of reach of the smaller coils is now within reach with the bigger coils. It gob smacks me as to the sensitivity & depth the 11" gets on smaller gold.
The small coils are great on the exposed bed rock surfaces that the old timers sluiced down to. I usually always start off with the small coils in these situations targeting the bed rock. There is no point in using a bigger coil on the bed rock as depth isnt an issue & due to these areas already having been flogged by god knows how many detector operators in the past it will be the small tiny gold that they missed. So you want sensitivity & not depth to start off with. But of course there is also going to be deeper ground off to the sides of the exposed bed rock that if there is gold there then the smaller coils arent going to get down to it. Even in the exposed bed rock there are some deeper creivices that the smaller coils wont get to the bottom of.
There is of course going to be a cut off point on how bigger coil you can use & get away with for depth on smaller gold where the bigger coils lack of sensitivity wont see them at depth. But if bigger gold is present then you will get it, where as the smaller coils will lack the depth on the bigger gold. It is all about compromise, smaller coils for sensitivity & small shallow gold & bigger coils for depth & bigger gold. So it pays to have a good selection of coil size & configeration: ie round coils & elliptical shaped coils. Round for out right depth & elliptical for poking in to tight spots like between rocks & in & around bushes & tussocks. Also, mono coils for there sensitivity & better out right preformance over a DD coil. But DD coils for use in discriminating iron & canceling out EMI & hot ground better than a mono all be it at a slight loss of depth & sensitivity. Of course most of you know this already but some may not.
I am talking Minelab PI detectors here.
Result on saturday before it started raining & hailing & driving me out was 8 bits for just under 3 grams for 4 hours.
Good luck out there.
JW :)
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