A back yard experiment.

Post Reply
User avatar
Easylife
Posts: 9394
Joined: Sun Jul 19, 2020 2:47 am
Location: Valhalla
Has thanked: 9524 times
Been thanked: 8388 times

Before our house was built in the 1930's this was just a village field. The back lawn is about 40 square metres and in early summer I gridded it with the Nox and 15" coil. The ground was a bit on the dry side and not too many targets showed, the oldest were about six bits of lead. There is variable iron presence over most of it apart from one quiet patch about 3/4 down the lawn.
But I felt that there would still be a few more bits to be had now that the ground is plenty moist as well as no doubt some masked by iron. So I went over it again slowly with the 6" coil scrutinizing every response and marking every repeatable target but not digging any yet as I plan to compare certain targets responses against the 11" and 15" coils.
Using the 6" coil I ended up placing 30 markers though most were iffy one way targets giving jumpy 20's with iron one way and just an iron response the other. At the bottom of the lawn were surprisingly 5 solid 2 way targets ranging from 6 to 17 though they appear very small and quite easy to miss. A cluster of perhaps 4 small or maybe even one large target was giving several 18's one way and just ferrous the other. There was a very solid repeatable 38 target which I exposed last time and left it there but I can't remember what it was!
As light was fading I had a quick waft over all of the markers with the 15" coil and found that it could not see a solid 17 non-ferrous target which the 6" coil had shown 4 depth bars so maybe not too shallow? The other solid targets were not as sharp but still clear non-ferrous diggers.
I'll compare all targets with the 11" and 15" coils then at least carefully dig the less likely to be iron ones. I just used my usual 15" coil settings of Sensitivity 25, Reactivity 5, Iron Bias FE2 0, and didn't change anything when using the 6" coil. Though I may as well compare a few settings over the various targets while I am at it, like maybe reducing the Sensitivity and increasing the Reactivity for perhaps better target separation? :Thinking:
D2 - 13"x11" coil - audio only.
Blackadder43
Posts: 3686
Joined: Thu Jul 09, 2020 4:08 pm
Has thanked: 2582 times
Been thanked: 2191 times

Ooooh, i love me a good experiment
Good on you fella, great learning experience with the Nox and its many coils
As light was fading I had a quick waft over all of the markers with the 15" coil and found that it could not see a solid 17 non-ferrous target which the 6" coil had shown 4 depth bars so maybe not too shallow? The other solid targets were not as sharp but still clear non-ferrous diggers.
Thats really interesting and does show that the bigger the coil, then the more 'surrounding' targets it drags in to be processed, which has an effect on the sharp targets the 6" found, and possibly waters down the signals

A good lesson to folk who believe the bigger the coil the more you find, sometimes it can be quite the opposite :ugeek:
Pete E
Posts: 2696
Joined: Mon Jul 20, 2020 10:05 pm
Location: North Wales
Has thanked: 3499 times
Been thanked: 2284 times

Easylife wrote: Thu Dec 09, 2021 8:56 pm Before our house was built in the 1930's this was just a village field. The back lawn is about 40 square metres and in early summer I gridded it with the Nox and 15" coil. The ground was a bit on the dry side and not too many targets showed, the oldest were about six bits of lead. There is variable iron presence over most of it apart from one quiet patch about 3/4 down the lawn.
But I felt that there would still be a few more bits to be had now that the ground is plenty moist as well as no doubt some masked by iron. So I went over it again slowly with the 6" coil scrutinizing every response and marking every repeatable target but not digging any yet as I plan to compare certain targets responses against the 11" and 15" coils.
Using the 6" coil I ended up placing 30 markers though most were iffy one way targets giving jumpy 20's with iron one way and just an iron response the other. At the bottom of the lawn were surprisingly 5 solid 2 way targets ranging from 6 to 17 though they appear very small and quite easy to miss. A cluster of perhaps 4 small or maybe even one large target was giving several 18's one way and just ferrous the other. There was a very solid repeatable 38 target which I exposed last time and left it there but I can't remember what it was!
As light was fading I had a quick waft over all of the markers with the 15" coil and found that it could not see a solid 17 non-ferrous target which the 6" coil had shown 4 depth bars so maybe not too shallow? The other solid targets were not as sharp but still clear non-ferrous diggers.
I'll compare all targets with the 11" and 15" coils then at least carefully dig the less likely to be iron ones. I just used my usual 15" coil settings of Sensitivity 25, Reactivity 5, Iron Bias FE2 0, and didn't change anything when using the 6" coil. Though I may as well compare a few settings over the various targets while I am at it, like maybe reducing the Sensitivity and increasing the Reactivity for perhaps better target separation? :Thinking:
Very interesting...Just been watching a video on YouTube about the Nox and the guy says that with the 6" coil you can reduce the reactivity right down to give you maximum depth...

His reasoning is that the 6" coil "sees" a much smaller volume of soil than the standard 11" coil and therefore is less likely to have more than one target in it...

Because of this, the machine doesn't need the extra speed that high reactivity gives, but that comes at the cost of less depth...

User avatar
Easylife
Posts: 9394
Joined: Sun Jul 19, 2020 2:47 am
Location: Valhalla
Has thanked: 9524 times
Been thanked: 8388 times

Blackadder43 wrote: Thu Dec 09, 2021 9:23 pm
Thats really interesting and does show that the bigger the coil, then the more 'surrounding' targets it drags in to be processed, which has an effect on the sharp targets the 6" found, and possibly waters down the signals

A good lesson to folk who believe the bigger the coil the more you find, sometimes it can be quite the opposite :ugeek:
Pros and cons of each coil though each best suits a certain situation with maybe one as a compromised all rounder?
D2 - 13"x11" coil - audio only.
User avatar
Littleboot
Posts: 752
Joined: Sat Jul 18, 2020 9:49 pm
Location: Normandy.
Has thanked: 1060 times
Been thanked: 1110 times

The level of dedication astounds me.I like the idea of marking targets out and not digging them until you waft over with another coil. Interesting comparison. I think I have got a tad relaxed about this kind of thing as i am not in competition with anyone else anymore. (Apart from Pete, of course, and he is a languid detectorist at the best of times.)
I don't have to fret about someone else going over my land with better tweaked settings and thus finding stuff I can't. I am not a massive fan of the small low-grade silver hammered's I get here in France. Don't mind missing them...So I have evolved some settings for my Nox which are pretty much beep-and-dig with the occasional tweak as I go along. I rarely stray from them as it kind of upsets my reading of signals. (I'd knocked it into 50 tones by accident the other day and it was atrocious to my ears.)
Same with coils. I stick with the standard doo-dah. It saves a lot of complication and fretting over choice. I suspect i have got lazy here in my part of Normandy. If and when I finally rock up on Brit shores again I suspect I will have to sharpen up my act considerably if i want to still find stuff. :lol:
"The forest was shrinking, but the trees kept voting for the axe, for the axe was clever and convinced the trees that because his handle was made of wood he was one of them."
User avatar
Easylife
Posts: 9394
Joined: Sun Jul 19, 2020 2:47 am
Location: Valhalla
Has thanked: 9524 times
Been thanked: 8388 times

Littleboot wrote: Thu Dec 09, 2021 10:20 pm I like the idea of marking targets out and not digging them until you waft over with another coil. Interesting comparison. I think I have got a tad relaxed about this kind of thing as i am not in competition with anyone else anymore.
I'm just bringing the other two coils out of hibernation for a chance for them to shine, hope they actually do in some way to actually cause me to use them again? :? Though am very comfortable with 15" coil and settings on my pasture.
Simples works well in Blighty too! :thumbsup:
D2 - 13"x11" coil - audio only.
User avatar
Easylife
Posts: 9394
Joined: Sun Jul 19, 2020 2:47 am
Location: Valhalla
Has thanked: 9524 times
Been thanked: 8388 times

Pete E wrote: Thu Dec 09, 2021 9:41 pm Just been watching a video on YouTube about the Nox and the guy says that with the 6" coil you can reduce the reactivity right down to give you maximum depth...
I'll try reducing the settings with 6" coil to see if that better defines any of these targets. I think that many will iron though maybe a few surprises too? I started with the ground balance at 0 but felt that after auto GBing it (25) iffy targets seemed more iffy so will check that again.
D2 - 13"x11" coil - audio only.
User avatar
Easylife
Posts: 9394
Joined: Sun Jul 19, 2020 2:47 am
Location: Valhalla
Has thanked: 9524 times
Been thanked: 8388 times

IMG_20211210_091804.jpg
D2 - 13"x11" coil - audio only.
Post Reply