TDI SL too nervous with NF 14x9 Evo

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XLOOX

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As I posted in Feb, I bought a NF 14x9 Evo at the end of 2019 & initial air tests were very promising it was as sensitive as the Sadie to small stuff and could go way deeper on big stuff.

Air test : Both with 16V battery, 10us, All, 8 gain, 8 GB, 320Ohm phones. Sadie is 1st number, 14x9 Evo 2nd number :

1grain Au ingot 70mm 70mm
0.5g Au coin 180mm 215mm
Oz 50c 370mm 480mm
massive iron 650mm 850mm

Was The Evo the One-Coil-to-Rule-Them-All ?

Umm not quite, In fact NO. I deliberately made it the 1st coil I used in 8 trips so have clocked about 30 hrs with her but it is a truly exhausting coil to use on the SL. Not due to weight but because it is almost TOO sensitive.

In nearly all ground the GB windowis a knife edge and every little ground variation & coil height variation comes thru the audio. You have to concentrate very hard & end up sweeping the same spot quite a bit to determine if the signal is a just ground, poor sweep technique or a target . Slow progress. Also I cant scrub the coil like I do the Sadie as it overloads easily.

The vernier GB knob mod was a godsend but I found that in a lot of cases I still needed 6-7 Gain & 12us delay to get a usable ground balance and it comes in close to 9GB in ground the Sadie is cruising at 10us, 8 Gain & 8GB.

With those settings the Evo can still pick up my 1gn test ingot on the ground but unless coil is at 0mm its not the screaming sort of signal you get on the Sadie.

In medium ground test results : Both with 16V battery, 10us, All, 8 gain, 8 GB, 320Ohm phones. Sadie is 1st number, 14x9 Evo 2nd number :

1grain Au ingot 50mm 30mm
0.5g Au coin 145mm 180 mm
Oz 50c 210mm 370mm ( GPX5000 gets ~500mm in hot ground)
massive iron 420mm 560mm

Ultimately the Evo is just not as forgiving & pleasant to use as the Sadie and in some hotter ground I am forced to go back to the Sadie due to inability to ground balance the Evo effectively. Using it reminds me a bit of my old ADS days !

Did she find any gold? Just a couple of 0.3-0.4g bits that Sadie prob wouldve got anyway.

Having said all that, even with those reduced settings, the Evo still well outperforms the Sadie depthwise on anything larger than a .22 bullet, as it should, so it is a keeper, but the Sadie will go back on as my 1st choice coil for the SL.
 
Must confess the NF 12 x 8 Evo is of interest, may well be ideal for the Tdi Pro. Suspected that 'hot' ground would be more of a challenge but it may play a role is less mineralized areas and going over tailings.. The Tdi series machines all 'love' the Sadie coils.. no doubt about that.
XLOOX thanks for the heads up and a very interesting read.
 

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