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TDI SL Ground Balancing In Hot Ground


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When circumstance allow, I like to go prospecting in Victoria's 'Golden Triangle', one of Australia's nugget hot spots. I use my beach machines, a Tdi Pro and a Tdi Sl Limited Edition. The Pro can be used for prospecting without any real issues, the Tdi Sl is more challenging in this environment. I'm going to focus on my experiences in hot ground, infested with ironstone, hot rocks and heavy mineralization. Not going to focus on depth, power or anything other than what it takes to get the machine to operate smoothly with the correct ground balance. The Pro machine has a hugh advantage, simply by vitue of that course and fine ground balance adjustments but this post is mostly about the Tdi SL. The single turn ground balance on the SL is a pain, it takes a bit of time to get it just right.

When the ground is hot the SL requires me to use a smaller coil, mono being the best. Mono coils in my experience are quieter, more stable and much easier to ground balance. Larger folded mono coils, duel field coils and the newer and hotter spiral wound coils all suffer when the ground is very hot, they are noisy and difficult to ground balance with a Tdi Sl.  The Tdi Sl with the stock 12 x 7 Miner John folded mono can be balanced but it will transmit more ground noise and be more difficult to ground balance when compared to using a smaller mono coil. Forgive me but I'm going to repeat myself a few times in this post.

 The smaller the coil the quieter the Tdi Sl will be and easier to ground balance, the reduced 'foot print' helps a lot. The very small 6 x 4 mini Jimmy coil is amazing in its ability to run smoothly and easily ground balance, but is too small to be practical most of the time. In comparison I can use larger mono coils on the Tdi Pro without issue, it has superior ground balancing ability on the goldfields.  A Tdi Pro mounted with a 8x6 mono 'Sadie' is my standard setup. The Detech 15 x 10 or Digger 14 x 8 also see some use as does the new to me Detech 8 inch mono when using the Pro. So whilst the Tdi Sl likes the smaller mono coils on the goldfields the larger coils are not an option. Yes the ultimate Tdi Sl setup is a small mono coil and an upgraded 16v battery pack for prospecting. Super light weight and beautifully balanced, respectable performance and versatile. Fun to use for all, kids and older family enjoy the light weight and balance. 

Allow me to deviate for a moment. Tie me to an ants nest and smother me in honey for stating the obvious. Serious prospectors are better served by more specialised Minelab machines... they are superb.  For me versatility is key at the moment and  I feel better served by my White's Tdi Pro on the beach, that stealthy little Tdi Sl 'urban PI'  is also a pleasure to use. When I invest in an expensive 4x4 and trailer some time in the future, then I'll make room for the more specialised gold machine. Hopefully by then  Minelab with have a light weight and well balanced SDC type PI in a Tdi Sl style body. Maybe White's will surprise us all. Fisher is coming to the party also. I need PI peformance and light weight, good balance and sane pricing.. more options arriving as time goes on.

Again my one piece of advice to anyone wanting to prospect using a Tdi SL in 'hot' ground, particularly in Australia, is this.. Use a small mono coil. Small duelfield coils like the older Jimmy, 7.5 duelfield, Miner John 7x5 folded mono or 6 inch folded mono coils, are all OK most of the time.. The Razorback 10 x 6 mono is great, the Coiltek Tdi series 6 inch mono is great, The Sadie is great. Keep it small and stick with mono and you should do well in all types of ground. The larger coils work well with the Tdi Sl in moderate soils and the beach. But when the ground goes bad it does pay to swap out for a small mono.

Again this is my experience in hot Australian ground. Hot is hot and I suspect many international Tdi Sl users have the same experience in difficult ground. Not looking to pick any fights but this is my experience with the Tdi Sl. Go small, go mono and boost the battery pack. All the best.

 

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As usual outstanding and useful information,i have never used the 'sl' version but i do own and use my TDI Pro,mainly use it with small coils and i totally agree with what you have mentioned about smaller foot print and the ability to GB the machine better and quicker.I also have much larger mono coils ie upto 18'' and 20'' for deep relic hunting,albeit the larger coils rarely come out to play but i bought them brand new when Jimmy Sierra closed down his website a few years back and got a selection of brand new larger coils for basically the same price as what i could pay for a much smaller coil and even that was including shipping and all taxes to the UK as well.

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Yep, that was a great read alright. One 👍 isn’t really enough so here’s 👍👍👍👍

Thank you Michael

Tony

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Thanks Karelian. Your suggestions for coil size on the TDI SL with 16 volt battery upgrade are virtually the same as what I am using. I quickly got rid of the MJD 12X8 folded mono for the same reason you described. It was too hard to ground balance and the 8X6 NF Sadie destroyed it sensitivity and depth wise. I recently picked up a Coiltek TDI specific 11" Mono. It is doing very well. I won't go any bigger than the 11" however. Those two coils are all I need.

thanks,

Jeff

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So far, I like the MJ 8 x 12. I'm not having any issues with GB, either. I really like the 8 x 6 Sadie, and the 7.5 DF is pretty close to the Sadie. I see no need for a larger coil for prospecting, but am starting to like the Super Pulse 8 x 14 for coins and relics. Most of what I'm searching, the targets are pretty shallow, and it lets me cover a lot of ground.

Jim

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  • 3 weeks later...
On 4/21/2020 at 2:26 PM, Jim in Idaho said:

So far, I like the MJ 8 x 12. I'm not having any issues with GB, either. I really like the 8 x 6 Sadie, and the 7.5 DF is pretty close to the Sadie. I see no need for a larger coil for prospecting, but am starting to like the Super Pulse 8 x 14 for coins and relics. Most of what I'm searching, the targets are pretty shallow, and it lets me cover a lot of ground.

Jim

Jim,the Sadie was always on my Radar here in the UK as so many good reports about it but as its not a common use coil as such because of the lack of nuggets they are rarer than 'rocking horse poo' and the cost of shipping one over is crazy high.But i do have a 7.5'' DF coil which i have had since i bought the TDI Pro but only used it may be twice,but as its mounted on its own bottom rod i changed it over onto the Pro and what a pleasure it is to use,light as a feather but it could well stay on the machine ongoing.

We especially in England have had some pandemic laws slightly relaxed as from the 13th May so this will allow us to go out again and do some pastimes including detecting but not in large groups etc,only say on ones own permission and if its totally fine with the land owner.But it may well be the ideal time to try the TDI Pro out with my substitute Sadie coil the 7.5'' DF coil lol.

Nearly all my many machines and rest assured at last count i had 25 detectors are mainly running smaller coils these days in the 5-7'' coil size,the largest current everyday coil that i use almost everyday is my Deus HF elliptical one,all my others Nox are running 6'' coils.

Thanks again for the input and your thoughts about using smaller coils on the TDI,batteries are all on charge as will be out detecting for the 1st time in a couple of months on my own permission/s with full blessing from the the landowners.

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6 hours ago, RickUK said:

Jim,the Sadie was always on my Radar here in the UK as so many good reports about it but as its not a common use coil as such because of the lack of nuggets they are rarer than 'rocking horse poo' and the cost of shipping one over is crazy high.But i do have a 7.5'' DF coil which i have had since i bought the TDI Pro but only used it may be twice,but as its mounted on its own bottom rod i changed it over onto the Pro and what a pleasure it is to use,light as a feather but it could well stay on the machine ongoing.

We especially in England have had some pandemic laws slightly relaxed as from the 13th May so this will allow us to go out again and do some pastimes including detecting but not in large groups etc,only say on ones own permission and if its totally fine with the land owner.But it may well be the ideal time to try the TDI Pro out with my substitute Sadie coil the 7.5'' DF coil lol.

Nearly all my many machines and rest assured at last count i had 25 detectors are mainly running smaller coils these days in the 5-7'' coil size,the largest current everyday coil that i use almost everyday is my Deus HF elliptical one,all my others Nox are running 6'' coils.

Thanks again for the input and your thoughts about using smaller coils on the TDI,batteries are all on charge as will be out detecting for the 1st time in a couple of months on my own permission/s with full blessing from the the landowners.

All the best, Rick. Hope you find some good stuff. In my testing, not a great deal of difference between Sadie and 7.5DF. One does better on some targets, the other better on others. Very close. And, as you said, both a real pleasure to swing.

Jim

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