I am still here and with a few answers you probably won't like.
First, the ground in OZ is dramatically worse than most parts of the world. Eric Foster tested that ground and in places it is 40 or more times stronger in mineralization than anything we have here. Thus, much of the ground is going to give problems one way or another and noises show up there that don't happen here.
BTW, did anyone tell Whites that virtually all of the SPP's do the same hiccup thing there? They should be told that. In simple terms, they should be able to use any SPP or SL and create the same signals, providing they have enough of a similar ground sample to use.
At least these discussions have brought out a few things I didn't realize and one of those is, the ML compatible DD coils will not work on the TDI series as they are built. So, some modification will be required if they are to be used at all. The lead foil placed on the crossover section is only a temporary fix. I think I have a better fix but won't know for a while. Also, a DD coil can be made like my home made one that will work fine.
As for the DD fix of placing lead foil on a DD coil, it shouldn't cause any or minimal depth loss. As for small gold, well, the coil design is what determines how well small gold is detected. Also, you can't simply try one small nugget and come to any conclusion. You will find there will be some .1 gram nuggets that will be detected and others that won't and this is normal.
Keep in mind the use of lead foil on a DD coil was a spur of the moment idea and not intended to be the permanent fix. On the up side, it does seem to work. One might try some fine wire and see if they can get it to work. If steel is used, the coil field will be intensified so one might see a slight increase in depth. Again, this is all speculation and may not work at all.
Now, as for the hiccup video's, they show two different conditions, one of which is somewhat of a benefit if you understand it and the other is a pain.
Raising the coil quickly is a pain since it does cause a hiccup in bad ground, but I am still working on a solution. Moving the coil over the ground and holding the coil level to the ground and a hiccup shows up it is telling you something. On the level ground, if a hiccup occurs like in the video there is a target there and the hiccup happens as a result of that target as it is buried in the ground that can cause them. Yes, the ground may seem mild to you but it isn't. Now, that target may be a piece of metal or a hotrock strong enough to generate a target signal. Combination of things can cause a target to only sound off in one direction or when searching enough, no sound, but the hiccup will still be there. Why? Simple, the hiccup is the result of a sudden change in signal response and a sudden change indicates some form of a target. The change can be the result of a sudden ground change, such as a rock in the ground that has totally different ground characteristics, a small target, or anything else that looks like a sudden change to the detector.
The hiccup is the result of the noise reduction design and how it analyzes sudden changes. In some cases, the sudden change is the result of the strong ground changing quickly such as in the video where the coil is raised quickly. We had a similar signal and were able to compensate for what was happening. That is why we don't have the problem here, especially when using mono coils. Now, dual field coils can cause some hiccups easier even over here. Hopefully, none of you have any of those coils. I think the true mono coils have black coil wires and the DF coils have a gray lead.
Now, a quick hiccup fix is to eliminate the noise reduction but to do so will eliminate the nice quiet smooth threshold everybody likes. Instead, I am working on a different method that will keep the noise reduction and still eliminate the hiccup.
So, relax, the SPP still is a good detector for the price.
Reg
