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Minelab Coil On Whites Tdi?


Rod K

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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.

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Thanks Rege for the reply.

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I hate to bring this up but this all gets complicated by the fact that not all TDI detectors are the same, nor are all Minelab compatible coils the same.

If you make a detector it has to pass within certain tolerances but there are variations. The same with coils. And as long as a coil is made for a specific detector you can be sure those two sets of tolerances align. Yet as manufacturers can tell you just building coils for a certain detector results in many rejects right off the production line. It is hard to do even for a machine you are planning on.

Now take coils with tolerances assumed for one detector and put it on another. Frankly, you just don't know. If the tolerances both swing the right way you are probably going to be ok. If the tolerances go in opposite directions you may have a problem. One guy may report a certain Coiltek coil made for the Minelab GPX (or GP or SD) works just great on his TDI, and you get the same coil and put it on your TDI and it is very poor. The chances are very high that every combination of TDI and non-standard coil is going to vary quite a bit.

And don't go expecting refunds for bad performance when you buy a coil made for one machine and put it on something else.

I am not trying to be a bummer here, just being realistic and warning people that putting coils made for one machine on another is an experimental thing. It is best done with coils had cheap so you are not out much if it does not work out.

I have put coils made for Fisher 13 kHz machines on Fisher 19 kHz machines and they seemed to work ok. What is not a great idea with PI detectors is usually a worse idea with VLF detectors. Here is what Dave Johnson (the designer) had to say on that subject.

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Don't know if it matters but this is a TDI SL.  I have the stock 12" dual field but i have read mixed reviews on it for gold. Planning to get one of the Miner John 5"x9" coils built for the TDI's for it soon. Thanks to all for the replies.

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Hey Rod, like we discussed a while ago, the SL has never had the power input to effectively use the larger coils for practical nugget shooting in most conditions. Whites, Coil Tech, Minelab whatever,  any coil larger than a 6x10 and the SL becomes unstable and noisy in mineralized hot ground typical of most gold fields. Using larger coils on the SL in these circumstances usually results in backing way down on the sensitivity while turning the ground balance up substantially to stabilize threshold. This results in poor performance at depth especially searching for small nuggets.  

Good performance with this machine is achieved by using the smaller coils allowing for sensitivity to be turned way up and ground balance setting kept low...... often turned off completely.

Larger loops can work quite well (on the SL) in more mild ground conditions like finding 50 cal mini balls on old battle fields or gold rings at the beach. The stock 12" spider works well in these areas.

I've spent a lot of money trying the larger coils on the TDI SL and while I have found some gold with them, 90% of my nuggets with this machine have come from using the ;TDI 6x10 DF,   Miner John 5x9 FOM, and TDI 4x6 Mono Shooter coils. Two of these coils were made by the late White's Chief Engineer Dan Geyer and are sadly no longer available.

It is said that Dan Geyer understood the Eric Foster design and potential better than most anybody. It would have been interesting to see where Dan would have taken the TDI series by now had he not passed so suddenly several years ago.

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The 6x9? Platypus coil works on my TDi ,BUT the coil ear holes were too small for the Whites bolt so I had to drill them out.

The 9 x 14 Nuggetfinder coil fits just fine tho. They both seem to work ok.I have an original TDi. No nuggets yet.

Coils are cheaper to buy in winter so I bought several used larger Nuggetfinder coils to try out .

Just need to get my butt to Arizona now...but nervous about potential  TSA hassles?

 

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