Whites TDI SL Search Coil Question

[Hard Prospector]

Bought my TDI SL this year and am really getting to know it well. However, there is one question that keeps nagging at me. Is the 12in. spider coil that came with the machine the best coil for nugget shooting desert washes and dry creek beds which is pretty much what I bought it for? Any advice would be appreciated, thanks.....Rob

 

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[Reg]

I have the SL and have several different coil sizes including the Jimmy, the 7 1/2" and the 12" factory sizes. I also have several different sizes I made myself. All work well.

Now, to answer your question, coil size is often a matter of preference. However, in rocky areas I prefer a smaller coil so I can get closer to the ground. Usually, it is easier to do with a small coil.

Since most gold found with a detector is small, then getting closer to the ground becomes important. If the detector can only detect the small gold to 3" or less, then sweeping over the ground with the coil at 4" above the ground doesn't work well if that is as close as one can get because of the rocks.

I like the Jimmy because I can get the tip into tighter places and that can be important.

I recommend you experiment with your present coil just to see what it will do. You can use small pieces of brazing rod for test targets if you don't have any small gold to work with. Many people use pieces of lead and that will work too.

What you will note with practice is the coil has more than one sensitive spot. Usually it is close to the center, but if the edge is close enough, usually within 3" or less, then the edge will detect the small stuff also.

This edge thing often causes people to dig a big hole before they find what they are looking for because they think the target is at the center. So, practice to see what I mean and then how to tell for sure just where it buried object is.

BTW, this edge effect works well to give you and idea of possible depth. Turn the coil so it is vertical and use the edge to detect a buried object. If you can detect it this way, then it is usually within 3" or so of the surface. If it is gone or very weak, usually the target is deeper. This works for coins also.

I can't stress enough the need for practice. Learn the best sweep speed to hear the weaker signals. All too often people sweep too fast especially if they have a long history of using a motion VLF for coin hunting.

The TDI and the SL need to be swept a little slower than the TDI Pro, since the Pro has a slight filter change. So, when taking advice, make sure to test it on your detector and don't just take someone's word for it.

Most gold found is small so often it pays to use the low conductor mode initially and then maybe go back over the area in the All Mode. Why? Well, the answer lies in how the detector works best and there is less noise to deal with in a single conductor mode. Yes, I know all about the minimal noise on the SL, in fact, this addition comes from something I came up with a few years back. Even though you can't hear the noise or hear it easily on the SL, it is there and it can make a difference in overall potential depth capability.

The special noise reduction circuitry works sort of like a squelch circuit, where it simply raises an internal pseudo threshold that has to be overcome by a target signal. Instead of hearing the warble noise, you have a nice quiet signal which is really nice. However anything that reduces the noise will increase the depth potential.

Reg

 

[Hard Prospector]

Thank you for taking the time to answer my question, great info and I really appreciate it....Rob.

 

[arizonaames]

I have found the Razorback 5X10 mono coil to be the best for very small gold. I can pick up a flat grain with a TDI Pro with it.

 

[Hard Prospector]

I just bought two new Jimmy Sierra search coils(8x14 Digger and the 10x6 Jimmy Loop) and have not had them out yet in the field. BTW, I was told that the engineer that made these loops is very ill and may not recover. May God bless him and his family. Thanks for the info on the Razorback 5x10 coil as I plan to keep expanding my loop selection.