4500 and 14'' NFA

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4500 and 14'' NFA

Post  koeh on Sun Oct 09, 2011 9:32 pm

How sensitive is the 14''NFA coil, the other day I was testing this coil on a 4500 with a half gram piece of gold, and it barely picked it up from 3 inches, the 4500 was in enhance any suggestions
other settings pretty much FP
gain 12
stabilizer 8
yet the 11''dd picked it up out of the ground from 4'' very easily, with sensitive extra

cheers

koeh
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Re: 4500 and 14'' NFA

Post  Guest on Mon Oct 10, 2011 6:15 am


Gday koeh

The 14" nuggetfinder advantage mono is my favorite coil on the 4500 for general use, lightweight, good ground coverage and excellent depth, the larger the coil the less sensitive its going to be on small pieces and air tests dont really mean much, that same piece buried in the ground will give a better signal.

If you want to chase smaller pieces then I would suggest the minelab 11" commander round mono coil or the minelab 8" round mono coil, the 11" commander mono on the 4500 is excellent and will also snag a deep bigger piece if you happen to wave over it.

You can of course get small bits with the 14" but you have to be using a slow swing speed, crank the gain up and take your time, and investigate any threshold changes.

cheers

stayyerAU

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Re: 4500 and 14'' NFA

Post  deutran on Mon Oct 10, 2011 2:16 pm

Hi Koeh
If your using the 14" then your chasing larger gold at depth.Most people using these are not finding gold everyday but rather looking for the deeper missed gold.You could expect this coil to start out performing your smaller coils at say 2g so try a test target and compare them.Sensitive extra will punch deeper than enhance in most situations but at the expense of ground noise when using mono coils,the DD is more immune to this so its probably a good setup for the smaller gold.Try your DD in mono and select enhance for a very good setup for fine gold in high mineral or you could use sensitive extra if possible.
Steve
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Re: 4500 and 14'' NFA

Post  TheGoldenChild on Mon Oct 10, 2011 3:21 pm

Hi Koeh
mate your 14"NFA should have picked it up easily. I usually find that size nugget even deeper then that using an 18"NFA in Enhanced ( in hot ground as well in the Triangle). The comparison test your doing with th DD is biased as Sensitive Extra is a more "Powerful" setting for small targets then Enhanced and will pick up the target a lot more audible then Enhanced. A better test would be to test both coils in NORMAL with all the settings identical.
NORMAL and Sensitive Extra should give you a good signal on your piece at that depth with either coil, unfortunately in the field (I can only speak of the VIC goldfields) Sensitive Extra is useless in highly mineralized ground and NORMAL is bearable if you go real slow and be prepared to dig up some ground noise and the odd hot rock.
If your 14"NFA can't pick up that piece with the settings you mentioned there is something definitely faulty somewhere.

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Re: 4500 and 14'' NFA

Post  Guest on Mon Oct 10, 2011 5:57 pm

Hi, I would be checking the coil definately. We use our 4500 and a 18" nuggetfinder advantage in WA and with our settings will pick up an undisturbed nugget of aprox half gram at 6" with ease. some of the areas that we have detected the hot rocks are BAD (understatement) and as day warms up gain is slowly turned back so can still detect. Temp makes a difference also. When testing our machine on signals we never dig target until tests done with different settings and coils. Once ground is disturbed it must alter what I call the halo effect around the nugget. Signal then seems to change once soil disturbed. We have spent much time to test and see what settings work and what do not. This time spent is well worth it. This is our findings, do not know if others have found this happens.
Best of luck
travelergold

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Re: 4500 and 14'' NFA

Post  koeh on Mon Oct 10, 2011 11:10 pm

stayyerAU

I was thinking about buying an 11''mono but the way this thing preforms I am not happy with it so dont really want to risk wasting money on another coil.

my swing speed is pretty slow with a dd and it had to be even slower with the mono to get a response.

deutran

next time i find a piece I will have a play with the pesudo mono /enhance/sensitive extra before i dig it out of the ground and see what happens.

TheGoldenChild

I have seen videos with people digging up little pieces with 18'' coils and giving a good response, so i cant understand why i have to be nearly touching it before i get a response.

travelergold

I am thinking there might be something wrong with the coil, I have only used it about 3 times as I am not confident with its performance.
I know what your saying with the temp as I have noticed that problem, but 90% of my detecting is at night as it is a lot easier.
Next time I find a piece I will try it with another coil if I am close enough to the car.

cheers for the replys fellas, that gives me some more things to think about.

cheers

koeh
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Re: 4500 and 14'' NFA

Post  Prospecting_Australia on Tue Oct 25, 2011 5:16 pm

As I use a 14" NFA, I thought I would add a few of my own experiences. I have found the coil to be surprisingly sensitive to small gold, even specimens, and possibly more so than the 11" commander. Why this is so I do not know. Fine specimens seem to sound clearer, although very faint, whereas with the commander they often sound broken up and can be easily missed. I have picked up 0.1 - 0.2 gram nuggets at 3-4 inches in mildly mineralised ground without any problems (using enhance), so you definately need to investigate why you can't hear a 0.5 grammer at 3 inches.

The coils are also very good at finding nuggets in heavily mineralised ground that are slightly deeper, perhaps missed by smaller coils.

You also need to take into consideration that Sensitive extra is more useful in mild soil conditions than highly mineralised, as TheGoldenChild has already pointed out. Another thing is that the setting is more suited to DD coils than monos, although it can be used on both.

I always swing this coil in virgin ground or where I want a tad more depth.
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Re: 4500 and 14'' NFA

Post  Nightjar on Tue Oct 25, 2011 8:26 pm

GoldenChild,
Maybe I have misinterpreted your message, Sensitive Extra timing will not function when the front switch is in Normal.
To use this setting and the others Sensitive Smooth etc the front switch MUST be in Special.

Cheers
Peter
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Re: 4500 and 14'' NFA

Post  TheGoldenChild on Tue Oct 25, 2011 8:37 pm

Yep Nightjar maybe I didn't phrase it right. Should have said " Normal OR Sensitive Extra should give you a good signal on your piece at that depth with either coil ".
In other words either setting.
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