Press Release

Monday 12th. February 2001.  The following report was given to Finders by Terry Jefferson for publication on our web site.

TESTING THE GP EXTREME
An independent test

Minelab has done it again – produced another detector to better the last three, namely, the GP EXTREME.  The new machine looks great, with a different colour, smaller battery pack and a carry case.

All the advertising suggests that this detector is the ultimate for depth with claims of up to 55% deeper than the SD2200D on some targets.  (Size and weight were not mentioned).

With much anticipation our club waited patiently for the chance to use one first hand.

It came on the 2nd/3rd Dec 2000 at our Christmas camp at Snake Valley.  I picked up the machine from Peter at Miners Den Mitcham on Friday 1st and proceeded to Snake Valley on Saturday 2nd.

Previous to this Peter B. and Herman had already bought themselves the GP EXTREME and had some success with a few small pieces of gold found.

At camp I set up a target area on lightly mineralised ground.  The object of this was to have the least amount of background noise, therefore the maximum depth all detectors should operate at.  A thin rod was hammered into the ground with 1” marks to allow the targets to be buried, keeping ground disturbance to a minimum.

The first 5 targets were ½ gram ball sinkers (lead)

                        1 Buried at 2”
                        2     “      “ 
                        3     “      “ 
                        4     “      “ 
                        5     “      “ 

The next four targets were 1.5 gram sinkers slightly flattened to give more surface area

                        1 Buried at 8”
                        2     “      “ 
                        3     “      “ 
                        4     “      “ 12”

The next seven targets were

            1 - 13.6 gram ball sinker buried at 13”
   
                     2 -     “          “          “          “       10”
   
                     3 -     “          “          “          “       16”
   
                     4 -     “          “    slightly flattened  14”
   
                     5 - 100 gram ball sinker          “    16”
   
                     6 -  39 gram ball sinker           “    12”
   
                     7 -  39 gram  “    slightly flattened  14”

I myself have an SD2200D, and tried my test patch with the following results using a Coiltek 14” Mono which I have had some success.

            Results – 3 out of 5 first line of targets
   
                         3 out of 4 next line
                            6 out of 7 last line

To me the results were okay, however I was dis-appointed at not hearing the 13.6 gm (nearly ½ oz) target at 16”.  I also tried the 10” elliptical Coiltek coil which also did not perform as well as expected on the smaller targets.  I assume that this could be due to the ‘halo’ effect (or lack of) associated with targets that have been buried for a long time.  This being the case, then all machines used in this test patch would be on equal footing.

All the club members were willing participants as there has been a lot of conjecture about each detector being manufactured to tolerances which may affect the depth to which a detector can work to.

To start with it was SD2100 Vs SD2200D and the results were – those who used the DD coils only heard half the targets (8 out of 16), and those who used mono-coils heard about 70% (11 out of 16).  It is interesting to note the 2100’s and 2200’s had similar results in depth and sensitivity.  The main thing that came out of this is what was interpreted as a target.  Those who listened to only sharp sounding targets could not distinguish a disturbance in the threshold which to me could indicate a target.  Those that ran no threshold did not hear the quiet targets.

After this came the GP EXTREME.  The signals it gave are quite sharp, much like that of the 2100 (the 2200 is relatively quiet).  Peter B. had his GP EXTREME for about a week and gave us his indication on how to set it up for best operation.

The settings were:
                               
1      Deep
                                2            Sensitive
                                3            Mon

The results –

Each person that used the GP EXTREME had no better result than either a 2100 or 2200 using each coil, 11” or 18” in Mono or DD, produced the same results, even when using enhancers and twiddling the knobs to produce the best target sound, the result was the same.  We also tried some Coiltek coils with the same result.

IN OUR TEST PATCH IN LIGHT MINERALISED GROUND
THE
GP EXTREME IS NO BETTER THAN 2100 OR 2200

This puts the thought into my mind – is this just a 2200D with a couple of extra knobs, upgraded exterior, carry case, higher price tag and plenty of advertising hype to go with it to confuse us so that we part with our hard earned money?

Maybe a demonstration by Minelab to show us the results they are advertising would be appropriate at this stage. (one of our club outings would be good).  It would be interesting to know how Minelab test their detectors – maybe an air test or in the ground as I did?

All is not gloom and doom however, as some in our club swear by their older trusty, tried and proven detectors.  After a small demonstration by one of these devotees I decided to try one for myself.  I borrowed Les Ringrose's Whites V-Sat.  It is manual ground balance with a few other knobs which I didn’t know much about.  After a few minutes tuition in ground balancing I was set to go.  I called to a few of the other members who were also interested in this ‘relic’ which I was about to try.

On the first line each target was clear and crisp, much to my amazement as well as everyone else’s.  (The Whites V-Sat has external audio so that everyone can hear).

The second set of targets was equally clear except for the last one (1.5 gm @ 12”), which was fainter but still quite audible.

The last set of targets would surely be out of reach of this small, antiquated machine, surely I thought.  Much to everyone’s amazement every target was clear.

The 13.6 gm (nearly ½ oz) @ 13” and 13.6 gm @ 16” were quite clear in contrast to the SD2100, SD2200D and the GP EXTREME which all had difficulty.

A footnote to this is that the owners of these detectors said that targets were quite hard to hear in highly mineralised ground and that you have to know your machine and be experienced in interpreting the signals.  A lesson for all detector operators.

Terry Jefferson

Committee member of the Victorian Metal Detector and Prospectors Association

 (V.M.D. & P.A.)

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