9 posts in this topic
Just with the Minelab PI coils being used on the TDI's. I've heard that once you get over about 14" with some coils the TDI's struggle to run them regardless of pulse delay settings etc? Was wondering if anyone has had any success with a larger coil on a TDI? Most, in Australia at least, seem to have success with smaller coils on the TDI series like NF Sadie & 12" x 7", 14" x 7/9" etc. Only ever heard of one being used with a 16" Coiltek but never seen or heard back any results with it, although I see one bloke said he tried one & then sold it going back to a Coiltek Blitz 14" x 9" which runs fine at 10uS. They seem to do well on small gold with the smaller coils here @ 10uS.Was wondering if this is why Miner John/Razorback are making coils specific to the TDI & Minelabs I.e. they have a 14" round for the TDI but it's not compatible with the Minelab PI's. They do however have other coils specifically for the Minelabs.
By Rod K
Has anyone used them on their TDI and if so, how do they do on Gold? Especially interested in the larger coils like the 12"x15" mono for the GPX. Will it work on the TDI ?
Would it be a good choice for covering a lot of ground prospecting for nuggets and will it find the smaller ones still? Would it be any better than the stock 12" dual field? Any experiences and help appreciated.
I recently added a PI unit to my weapons hoping to get further depth on caches of buried cans and bottles at 3 feet and deeper. I am mostly using the detector only to find the deeply buried pits of ferrous cans/ "trash". I know there is a learning curve to all new equipment but am throwing out some questions here for those who have used the White's SPP.
First thing I notice is the detector is very sensitive especially to shallow scatter like concentrations of scattered nails and wire, especially wire in coils or even hangers bent in round loops sound like a much better target. I have read that adding a much larger coil like an SEF style in 20x17 format will eliminate some of the "noise" of semi surface items as well as add a bit of depth. My question is having the SPP without the Pulse Delay setting am I going to have a problem running these coils? I had read elsewhere that guys turn up the Delay setting when using the larger coil and the SPP does not have this ability.
My first time out experimenting on finding a large deep target of cans I knew existed I ran the coil that came with the unit and in range on controls suggested in thres and gain. I picked up a number of small sharp high tone signals and dug them just for experience. I came up with bottle caps, loose change, a 2 dollar Mexican coin and a nice men's gold band. But these are not the type of targets I seek and would rather hear the deeper low tones that suggest concentrations of deeper buried metallic objects (trash). I was able to easily find the pit of old cans that were about 3 1/2 feet down but noticed it was very hard to pinpoint the signal and it seemed to overload or max out the detector signal. When switching to OFF on GB and running in an non motion mode I did well but experienced the same overload type effect on deep concentration target. When I turned the GAIN down some it helped with average targets of say 6 pack of cans at 2 foot, but I lost the ability to pick up the deep target.
I know I am looking to use machine in ways most are trying to avoid in digging "trash" but just looking for any suggestions on coils and settings that may help with my learning curve.
By Mark Gillespie
To start with I must confess and hope the following information doesn't give the wrong impression about the TDI SL. It has a lot of potential, but only in certain locations not loaded with a lot of nails.
I started inquiring about some old locations I hunt. Most of the locations are old, shut down schools where coal was used as a heating source for decades.
Before the EPA was birthed most people did what ever pleased them when it came to disposing of waste, regardless of what it was and these old school sites are no exception. The burnt coal waste was spread over many acres of school property which created some extremely harsh ground conditions. Grass and weeds find it hard to get a start and most areas are void of any vegetation. Most of the school grounds look like Martian landscapes with small BB size or smaller pieces of coal waste everywhere. This material attracts to a magnet with little effort and can reduce depth of all VLF detectors by well over half. In fact until recently maximum detection depth was actually 2-3”, any target deeper would give a solid iron audio report if any sound at all. After many years of hunting these areas all but completely unsuccessfully I finally purchase a White’s TDI SL.
It turned out the SL opened up these old sites and many nice coins and relics were unearthed, but not without many trials and numerous adjustments.
Case in point: one particular area had been, in my opinion hunted out with many different VLF machines over a 10 year period and I was certain there were no good targets left. I had been hunting about 15 minutes and all the SL was giving were very short audio reports, which sounded more like chatter or EMI and not targets. This prompted me to increase the time delay to about 15 “which increases the time before a transmitted signal is analyzed” thinking the small pieces of coal waste were the short reports I was hearing. Continued hunting another 5 minutes and noticed the short audio chatter continued but not to the same magnitude. Stopping and increased the delay to around 17 and off I went hunting again. Suddenly I noticed the machine was running very quiet, to quiet.
A minute or two later and a very loud low tone, which on the SL means a high conductor, I stopped and reduced the delay to 10 and found my definite answer. The coal waste was causing all the ground chatter and false audio reports. Increased the delay to 17 and recovered a wheat penny around 4” deep. Now to be honest I had to stop for a moment and think about what just happened. Decided to start over I returned to where I began hunting and discovered I had passed right over many good targets. After digging a few more wheat’s I decided to start checking these targets before digging and discovered if I decreased the delay most of these targets became the short sounding audio reports I had heard earlier. The PI was just the trick to discovering some nice coins deeper than 4” in these barren areas.
I must add the SL is not the best choice to make if there is an over abundance of nails because of the very limited discrimination capabilities of this particular machine. As a final note I must admit this machine has opened up a lot of hunted out harsh ground sites.
I am in the market for a pi detector for beach hunting. I cant afford new so used will have to do me. The TDI Pro is at the top of my list but I do have a chance of picking up a good GP3000 with DD coil at the right price. I know that the Minelabs are not to fond of salts so I am wondering would the GP compare in performance, depth wise to a TDI?
By Mark Gillespie
Recent discovery of the conductivity switch on my White's TDI SL.
The video shows what I've found.
It also works the same with the 7 1/2" dual field coil.
Just the opposite happens if you run the machine with the conductivity switch to high, low conductors are also heard.
These results are the same as in ground targets to about 4" deep.
More information to follow......