Erratic 900 Nox

[Digalicious]

4 minutes ago, HardPack said:

Check out “Metal Detector Advice & Comparisons” under topic “EQX 900 & Legend Separation”. Chase may be on to something.

Thanks. I'm heading out for the day, so I'll check that out later.

On my Legend, there is a 4" depth difference between 16 and the maximum setting of 30. I could be completely wrong, but I suspect that a similar sensitivity depth reduction would result in a similar depth reduction on the 900. 

[HardPack]

2 hours ago, Digalicious said:

On my Legend, there is a 4" depth difference between 16 and the maximum setting of 30. I could be completely wrong, but I suspect that a similar sensitivity depth reduction would result in a similar depth reduction on the 900. 

I was using the 11” Nox coil in the “Separation” post. I was attempting to arrive at a stable baseline detection depth for the EQX 900 in a specific soil type GB 40. I started with the Sensitivity setting adjustments with Recovery 1 & IB 0. Then to get a feel for recovery setting adjustments impact of depth with Iron Bias at 0, Sensitivity 18. Then a separate run over the buried coins adjusting Iron Bias settings with Recovery at 1, Sensitivity 18.  

At the actual detection site the soil type differs with a ground balance of 30 (isolated areas at 54), has ground noise plus an overlaying carpet of buried rusted tin and major EMI. On this specific site the recovery & iron bias setting are headed up in order to cut down through the buried ferrous trash in search of deeper non-ferrous targets. This is driving the need for the ferrous/ non-ferrous target separation. Prior on site use of the coils with EMI demonstrated the stock Nox coils were more stable than the coiltek. How much depth will actually be lost, this portion is still a work in progress. I would suspect in higher mineralized soil types sensitivity adjustments would have a proportional impact on detection depth…

 

[Chase Goldman]

2 hours ago, HardPack said:

I would suspect in higher mineralized soil types sensitivity adjustments would have a proportional impact on detection depth…

It's not proportional.  The sensitivity to depth relationship is non-linear.  It plateaus (i.e., the steepness of the curve significantly decreases) at sensitivity levels above 22 or so in my experience.

[Digalicious]

35 minutes ago, Chase Goldman said:

It's not proportional.  The sensitivity to depth relationship is non-linear.  It plateaus (i.e., the steepness of the curve significantly decreases) at sensitivity levels above 22 or so in my experience.

I found a post I made from about 1 year ago, showing a depth / sensitivity test on the Legend. The results were also nonlinear.

For the sensitivity test, I used the 6” coil, a silver dime, M3, and the default of 5 for the recovery speed. Note the 1" difference from 24 to the maximum of 30, yet there is a 3" difference from 16 to 24.

30-10”
29-9.5”
28-9.5”
27-9.5”
26-9”
25-9”
24-9”
23-8.5”
22-8”
21-7.5”
20-7”
19-7”
18-6.5”
17=6.5”
16-6”


 

[HardPack]

44 minutes ago, Chase Goldman said:

It's not proportional.  The sensitivity to depth relationship is non-linear.  It plateaus (i.e., the steepness of the curve significantly decreases) at sensitivity levels above 22 or so in my experience.

 

4 minutes ago, Digalicious said:

I found a post I made from about 1 year ago, showing a depth / sensitivity test on the Legend. The results were also nonlinear.

My bad. Good information to know about both detectors. For a stable clean signal it appears in this dirt 8 inches is close to the depth detection limit with the 11 inch coil at sensitivity 18. Bumping up to a higher setting increases background noise but workable; at 8 inches the weak signals increase as does the TID spread on shallower targets (dime/penny). Getting closer to breaking through the iron curtain. The bedrock isn’t far enough down to worry about the maximums. 

[mcole]

Still following. Still have not worked on this.