Radar Image Detector! OOOOOO OOOOOO OOOOOO!

hi..      

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Hello to Airoia and Silver79. I shall try to answer your questions as best as I can.

Ferrous discrimination: It only has 2 modes, on and off. Most of the time I have searched with the discrimination in the OFF position (my main rule is to dig every target detected). I tried it with the ON mode in a trashy area and it did not pick up any cans/pulltabs/nails, so I can say it works well.

Soils and rocks: I used the NGR for 4 days in an area that has the worst soil I have ever seen around here. It ranges from reddish acidic (pH is 3.9 to 4.6) tropical oxisol with very high presence of iron (tested with Lamotte soil testing kit and the content is off the scale) and clay content (30%-60% w/w) to a mixture of colluvium and riverine alluvium that is also liberally laced with iron and aluminum. Heavy metal poisoning leading to premature senescence/poor root growth of crops is common, and even the hardiest of weeds like imperata cylindrica and mikania micranthum/cordata grow poorly there. I have an agriculture background and am very familiar with local soils/vegetation. The NGR punched thru those soils with ease, and I was relieved. For comparison purposes, the honest salesman from Mala Geosciences (they make real GPR units that are very expensive) told me that their machine in this particular area could only get less than 1 meter of penetration due to the soil characteristic. The 2 meters depth I have gotten so far with the NGR makes me happy.

With regards to hot rocks, I encountered 6 or 8 (I forget the exact number) spots where the unit went off, and analysis showed ferrous metal at zero cm. It was just small surface rocks that had some iron ore in them. The on-board user guide states that the unit is also capable of penetrating rock, but it must be ground-balanced on the rock first. I stood on large rocks with certain carvings on them, balanced the unit and nothing was detected. A Hitachi EX120 Landy was used to remove the rocks and nothing was detected under the rocks or in the rocks (after they were broken up). Until I encounter a target in or under large rocks, the workability of this feature is still uncertain.

Coil type: The NGR is the model that comes with the general detection head rated to go down to 5 meters.

Size of metal detected: At slightly over 2m (I forget the exact figure...I think it was 210cm or 206cm), the target was approx 15cm square and 8cm tall. The depth analysis of the NGR is amazingly accurate, but you must properly ground-balance it, and sweep slowly and smoothly at a constant height for more accurate results. I worked the unit with the accelerometer function OFF because in some places, I had to be lowered with a rope to detect on near-vertical drops, and I feared the accelerometer would bias the detection results.

Weight of the unit: I estimate the weight of the box with screen to be 2.5 to 3kg, the rod and general detection head also weighs about the same, so it's about 5kg. My neck, right arm and back are still aching as I type this. One day I will weigh the unit on a scale.

How quick is the unit: I do not really understand this question. If you are referring to recovery speed, I did not test for that. It takes some time to boot up, and it is impossible for me to move quickly while wearing the box on my neck and holding the wand.

If you have more questions, feel free to ask, and I shall reply whenever I am back in town. If this machine helps just one person avoid an unexploded grenade or land mine, then I consider all this typing to be worthwhile.




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http://www.thunting.com/smf/index.php/topic,4854.msg36458.html#msg36458

Hello to uksearcher, and congratulations on your find! I am waiting for my bungee, hipstick and harness to arrive from the USA within the next 10 days or so, and shall report on if such a rig can help alleviate the weight of the rod and detection head. If the weight can be distributed to other parts of the body, detecting with the Nokta will be much more enjoyable.

Since the Nokta Golden King claims to be able to detect non-metal objects as well, I am going to see if it can find chunks of amber and copal in the ground. I read somewhere online that it uses soil-displacement algorithms. Maybe the machine has to be de-tuned in manual ground balance mode for this purpose. If any other users care to experiment, please let me know your settings and results. I suspect that IF it can detect amber chunks, they will show up as blue voids on the screen.

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Thanks Andy!

 

nvchris

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http://www.thunting.com/smf/index.php/topic,4854.msg37044.html#msg37044

Divarnet, thank you for your views. There is no need to feel sorry for this Nokta owner because he is very happy with the field performance of the unit. In fact the NGR has become my main detector, and my Discovery TF900 is now my backup machine. It is perfect for cache hunting. 2-3meters depth is what I need, and so far the machine has proven itself to be reliable and stable in both hardware and software.

However, I believe that no single detector can suite every field condition and different kinds of targets/goals need different detectors. I have never hunted single coins before, so it was with great interest I read your pdf file on the SEF coils. The greatest depth in the review was 17 inches on a crotal bell. That is too shallow for my needs. Have those Detech coils ever gone deeper on larger objects in your experience, and can they detect cavities?

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