GPX 5000 - some gold hard to hear


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Hi All,

Getting ready for a trip to SW US, and doing some preliminary testing on my GPX 5000.
I have some test samples glued to a plastic chip that I use to verify the basics, but curiously, this one sample (0.16 gram , call it 2.5 grains) would not make a peep.
Not only going over with coils, but even the coil edges did not register this one.
The other , flatter 0.19 gram piece was detected by both coils.

Using both NF 14 x 9 and 8x6 Sadie coils  - got no response from either one.

I was on a freshwater beach with the chips just on top of the sand - not too close to any interfering target.

Settings were

Mono,
Fine Gold,
Gain 11 or so,
GB fixed ( i adjusted it for the area),
Audio Deep,
Response Normal,
Search Mode General
Stabilizer and Signal left at factory settings.

Any thoughts on settings that could make small bits like that one more detectable?

Thanks everyone!

-Scott

sample_pt19g.jpg

sample_pt16g.jpg

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Wow! Interesting. Do you have a MInelab Commander 8" to test by any chance ?

Can you try again using Sensitive Extra with the Nugget Finder's ?

Lastly can you also try the Normal, Audio. Instead of Deep.

 

Edited by garikfox
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Hi Garikfox,

Thanks very much for the suggestions.

I do not have the Minelab Command 8" coil, but I will try Sensitive Extra with the NFs.

I had originally tried Audio set to Normal, and also moved the gain from 11 up to 16 but no joy.

Understood that less aggressive timings will  perform better; started on Fine Gold timing because the area I will be prospecting has quite a bit of mineralization and ironstone.
From my research on this forum and other places, that is the timing I expect to be using in the field, so I was trying to pick settings close to what others recommended for that timing.
I realize that this more aggressive setting will introduce some performance degradation, so I guess it''s about finding what works at the time and place one is searching.
Also, I understand the nugget characteristics(size/shape/surface area etc) will definitely affect what can be detected.

I'll have a week out in the field to play, so will try a little of everything.
Just a little concerned because the nugget I can't hear came from the area I'll be working... :(

I have read on this forum and others about much smaller nuggets being found (sub 2 grain, sub grain), so it makes me question my setup, naturally.

Thanks again for the tips, I am just wanting to make sure I have not overlooked something very basic.

I really appreciate everyone that posts to these forums and sharing so much information.

-Scott

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  • 2 weeks later...
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Hey Guys,

   That is common, as the gold types (solid, flat, crystalline, porous and such) can cause the detector to react differently from a good signal, broken signal or no signal at all.  I have seen nuggets in the 4-5 gram range that will not respond on the Minelab PI's, even with a small gold.  I was mind boggled at first, but seen it first hand many times.  For the most part, the Minelab PI's, especially the GPX series will scream on small gold nuggets even with the stock 11" Commander Mono.  

If you're chasing small gold nuggets, my favorite timing is/was Special/Sensitive-Extra.  You need to be in Special on the front panel and then Sensitive Extra on the menu screen.  Keep your audio in Normal if possible and run your Gain at 10 or higher.  You should be able to find 95% of all the small gold out there under a few grains in size near the surface or on bedrock with a GPX 5000 and stock 11" Mono or smaller Mono.  The best searchcoils for small gold chasing are the Nugget Finder 8x6 Sadie Mono or Coiltek 6" Round.  We carry both of these coils and they are very popular for small gold and working in tight spots and better pinpointing.  

Hope this helps a bit,

Rob

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