prospectinginoz

There is the latest update on my forum: http://groups.yahoo.com/group/ProspectinginOz/message/7203 It is very close. douginpoz

Inhere is the best you can do to respond to my posts! Pathetic! You run away from the tough questions and then try to divert attention from the questions that you won't or can't answer by scattering red herrings! I will not waste any more of my time responding to your drivel.I should have known better in the first place. Have a very nice day, douginpoz

Jp, You have not read or fully undertstood my post.However you have at long last acknowleged the existence of electronic holes in the gpx 4000! I have a question:why should there be ANY electronic holes in the 4000 in S/S mode regardless of the ground conditions?This surely is a serious flaw is it not? How does how one determine whether the ground is CONDUCIVE to smooth mode or might be better suited to using a DD coil? The ground that we tested on was suitable based on our rigorous in field testing with our own designed Pi and associated instuments ( measuring time constants of the ground,signal amplitudes "on time" and "off time" vs ground decay or TC vs Tx pulse length)and in some cases the SI values as well. Smooth mode was designed in my view for highly variable ground that has a significany portion of SPM particles or in other words demonstrates significant frequency dependent magnetic viscosity,do you not agree? To repeat we have data from many ground types including probably the worst in Vic and perhaps the world? and the test sites while not as mineralized as Beggary Hill do exhibit from our data some spm characteristics. I doubt that very much ground in the USA for example would be any where near the mineralization level of our test sites and in most cases would be surprised if S/S was ever needed or indeed a gpx 4000.As for :"Smooth mode is a tool just like everything else on a Minelab machine which you and your mates have failed to see on each and every subsequent offering from Minelab since the release of the SD2000" I disagree otherwise I would not have a 3000 and would not be going to a 4000 which is without doubt the present state of the art for small gold in hot ground at least for the time being. I accept that there have been significant improvements in the platform in some areas but in others such as EM noise there has been in my opinion little or no improvement in fact the problems may well be worse and ML still cannot give us a reliable Fe/non Fe Pi discriminating platform (something we have been able to do on a shoe string budget in only 6 months with our own Pi design and as you will find shortly others have achieved the same thing). Also some of us want to have a platform that will give more depth on bigger nuggets and there is NO evidence that that ML have made any progress in this area since the SD2000 something that a number of 4000 owners in OZ have come to realize after seeing how their 4000's performed vs modified sd2000's on long TC targets. These folk are not fools! They are very experienced (some have many, many more years that yourself) and have been very successful in both Vic and WA. cheers, douginpoz

With respect Inhere you do not know what you are talking about as evidenced by your many" learned" LOL! posts on forums! What evidence do you have that the testing was done over the wrong ground? For your info we have measured the TC and decay curves vs Tx length of the ground at the test sites (and other data as well) and at many other locations using our own Pi platform so I think we know far more about the ground conditions than you. What evidence do you have that we used the wrong settings on the 4000 in S/S? Perhaps you could tell us then what are the “best” settings and coils for the 4000 in S/S to maximize the depth and sensitivity to larger gold (5 grams and above). As an "expert "on the 4000 this should be easy for you! Do you dispute the fact that the 4000 in S/S has some gross electronic holes on a range of larger nuggets at shallow depths? What testing have you done to refute our findings? If these gross electronic holes on some larger shallow nuggets in S/S are mythical and due to us using the wrong settings then perhaps you may enlighten me as to what settings we should use. And for your interest a modded sd2000’s on light to moderate mineralization will more than match the 4000 on the small stuff particularly if the clock oscillator frequency is increased. And of course the 4000 cannot find the “invisible” gold that Reg’s much cheaper modified GS5 can or for that matter one of our designed Pi detectors that I pictured on my forum. I suggest that you have a look on the forum at the tiny nugget that our Pi will find at 4”. Try getting a signal on this nugget with your 4000! ML will never be able to find these tiny and invisible nuggets with there present platform simply because they cannot sample early enough and they will never equal the depth capability of the SD series on larger deeper gold for a variety of reasons including DVT. cheers, douginpoz

"Sensitive timings have been optimised for an improved response on smaller, shallow nuggets. There is a slight loss of depth on bigger targets, so you should not use this setting when seeking out large deep nuggets". http://www.nuggethunting.com/forums/index.php?showtopic=4596 Steve, what happens with the 4000 is far more than just a loss of depth in S/S. There are some gross electronic holes on some large nuggets in this mode as we have shown time and time again. I would call failure to detect some nuggets from 1ozs to 7ozs at 12" far more than a slight loss of depth! Then of course we have been unable to demonstrate that the 4000 in ANY mode will go deeper on medium to large gold than previous models, in fact quite the opposite. At least two modified SD2000's that we have tested extensively against the 3000, 3500 and 4000 will go measurably deeper on larger nuggets or long time constant targets. This is the reason why a number of very experienced 4000 users here have recently purchased modified SD2000's after testing there own machine against the modified SD2000's.There are many good reasons as to why the GP series will not go as deep on large gold as the SD series, one being that ML have been moving towards improved depth and sensitivity to smaller gold (which is what the market wants).You cannot easily have any detector that is optimized for both small gold and large gold at depth. The 4000 is without doubt superior to any previous models for small gold in any ground but if you want to hunt for the bigger deeper stuff as some of us do in OZ then the 4000 is NOT the way to go. It will detect deep gold no doubt about that at all, but it just will not go any where near as deep as a modified SD2000 from the testing we have done. douginpoz

The ground we test in Vic Australia is undisturbed (by man) except for the small diameter horizontal holes ( which we then line with plastic pipes) bored into the banks of undisturbed gullies in the goldfields. We now have a number of such sites where we at some future date we will be able to compare results on the same target,same detector,same coil etc but different ground matrixes. This I believe is a close as you can come to the real deal and to my knowledge is unique for the non commercial detecting sector. We have found that over many years of testing at the Dunolly site that the results we get reflect very well what happens in the field. Both coiltek and nuggetfinder use to the test site to evaluate their new coils before market release. Doug http://groups.yahoo.com/group/ProspectinginOz/

Why not use Silver or Aluminium wire.But conductivity is only one criteria for coils.Inductance and coil capacitance and shielding and Q are probably more important. Some people have used silver wire and one person even suggested using gold wire! Our testing with 3000's and 3500's shows that Al blocks do behave somewhat like native gold. The big advantage of Al blocks is that Eric Foster has calculated the time constants based on the dimensions of the blocks. For our testing purposes this is very useful as we want to see what happens to the depth of the ML Gp series when we use objects whose time constants are much longer than the transmit pulse length. Metals including Al reflect to some degree EM fields but he ability to readily induce eddy currents with EM fields is primarily determined by the metals conductivity. doug

Electrical conductivity x 107/W m at 295 Deg Kelvin (the bigger the number the more conductive the metal) Aluminum=3.65 Gold =4.55 Lead =0.48 Silver =6.21 Copper =5.88 Iron =1.02 Zinc =1.69 Therefore the closest metal to pure gold in conductivity=Aluminum. Iron is closer to gold in conductivity than lead.Native gold may have a lower conductivity than pure gold of course which would make it even closer in conductivity to pure aluminium. Data from: Kittel, Charles, Introduction to Solid State Physics, 7th Ed., Wiley, (1996) Doug

Are you saying then that Eric Foster is wrong in recommending AL blocks to us for depth testing Pi detectors as a substitute for gold nuggets? What do you think are the most critical factors that control depth and sensitivity for conductive targets with Pi detectors? If AL as suggested by Eric Foster is not a good substitute for gold nuggets then what do suggest we use and on what basis? By the way our Goldfields in Vic, Australia contain very little in the way of Al pull tabs or tops or foil. I have been hunting since 1981. Where possible we ALWAYS use natural gold nuggets (up to 19ozs) for our depth testing. However for testing at big depths this is not practicable (or secure!) as we would need nuggets of 100ozs and upwards.So we need to find a good substitute. best regards Doug

AL has a conductivity very close to gold. AL and gold of similar shape and size have Tc's that are fairly close.It is also what Eric foster recommends for testing and i don't know a much better authority. For testing of very deep targets Silver is very good because it has very long TC's ( more conductive than gold).ML machines really run out of puff on objects when the Tc's are >> Tx pulse length. doug

Can't answer,its a question that you should ask Dave.

The answer is yes,both professional gold prospectors and coin/treasure and relic hunters. Doug

It has been said on my forum that Dave has little credibility compared to people like Bruce Candy because he does not have any patents. Well to scotch this rumor here are two of his patents Patent for a code generator: US Patent Number 6237075. http://www.freepatentsonline.com/6237075.p...47c5ffca1d07c57 And: Direct Sequence Spread Spectrum Radio (as used by the military for low probability of intercept radio transmissions). US Patent Number 6,738,414 http://www.freepatentsonline.com/6738414.p...96e082ec8d7da2a He has other Patents as well but because they are involving the defense and military they are classified. The co author of these patents Pierre is considered to be one of the most brilliant mathematicians in the USA and I have been told has done work for NASA amongst others. Dave will apply for a Patent for the critical circuits and signal processing methods for the Pulse Devil. Also remember that the Pulse Devil is the result of more than 6 1/2 years of work.Dave is also acknowledged as a very fine analogue electronic engineer and his principles and Pi methods have been validated by other experts in the field and also by a large amount of bench testing. While this does not guarantee success in the field it should give some confidence to us all that the Pulse Devil is based on sound principles and will deliver in the field what it has done on the test bench. Doug

JP is it correct that the 4000 at times suffers from EM noise that cannot be tuned out and that you have to live with it or go home? If this is the case why was this not picked up in the pre production field testing and remedied prior to public release? Why could a gain control (sensitivity) control not have been incorporated into earlier model machines? Why has it taken 12 years to see this important circuit control incorporated into the 4000? Is this due to a very inflexible ML circuit topology, signal acquisition or processing method or a marketing strategy or both? Why has it taken ML so long to realize the benefits of Li-ion batteries and make them available for their Pi machines? You see JP the questions will not go away but your answers are in short supply. Doug Well as Dave says you do your worst and he will will do his best. I hope that their are a lot of crows available so that myself and Dave and Whites and Allan W can all eat them. By the way how do you cook crows? Doug Will do Reg.We have some other nuggets including one of about 5ozs that are giving very poor signals on the 3500 compared to some smaller nuggets at the same depth. Have not done any 4000 testing for a while and some of the bigger nuggets from our kit are being sold so we will have to find some substitutes. Now we have multiple test sites we will be better able to test the effects of varying mineralization on depth and sensitivity. But as you know we have other priorities at the moment. Interestingly a team from a well known detector company was at Dunolly last week with detectors and laptops.My lips are sealed! Doug

So what! Maybe you or others previously failed to work the area properly! JP how long did you test the 4000 for prior to public release? Were you first in line or down the list? Did ML take on board your views on the 4000 or were they going to go ahead and release it regardless? And stop running away with your tail between your legs when you are asked the tough questions or trying to distract and avoid them by scattering red herrings all over the place. And I love the insults keep em coming! It tells me I am getting under your skin! Obviously you cannot argue on the technical merits or otherwise of the 4000 or PD so you have to resort to the last bastion of a scoundrel, insults. Well as a scientist I have been insulted by the best in the business and I took their insults very seriously as they commanded respect because of their knowledge and publication record and international reputation.You my friend are a mere flyweight even though you I do enjoy your videos. From the "airchair bandit" and idiotic and insane minelab hater and basher Doug Do you think that all the previous Pi models that ML released were bug free? Doug