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Minelab PI Coil On White's TDI


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Thanks for stopping by and providing that explanation Reg. Though I got a chuckle when you say:

"In simple terms, the assumption that a TDI doesn't have enough power to power a large coil is totally false. Instead, the interaction of the filtering inside the detector is the culprit. So, what does this mean? Simple, modify the filtering and you could use larger coils much easier."

Simple for you maybe. I think most of us lack your electronic skills!

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Aussiematt'

Lately Iv been hunting for large deep "items" (no gold yet) with the TDI pro' I'm using a 12x16 minerjohn mono coil and operating in HIGH mode with the pulse delay about 15-18 and GAIN flat out.

My TDI is modified but a STD machine will still work fine just maybe not at full GAIN.

Now' "yes" using HIGH mode your not going to find small gold so turning the pulse delay up doesn't matter much, actually you probably won't detect any gold less than half an ounce, so using HIGH might not be the best option.

The reason I'm using high as it's nice to only dig 4-5 big deep targets a day especially if gold has already been found in the area your hunting in, running in HIGH also allows you to turn the GB back a little and completely ignore our hot Australian soil that's means no more ground noise even with a big mono coil and no digging hot pockets (something you have absolutely no hope of avoiding in ALL mode) and smooth quiet detecting other than the odd funny sound.

Most larger coils will work but you have to use HIGH, Iv also got a 20" minerjohn mono that's identical to the 20" Grande coil, Iv also heard good reports of the old minelab 18" dust bin coil.

Basically dig a repeatable signal and a deep signal like the 2ft deep can I dug up on the weekend will be pretty quiet but still a low tone and repeatable, also I dug a solid chunk of steel about the size of a 20c coin about 10" but that was a good loud signal.

One of the best things about using HIGH mode you can use it in trashy areas and not dig up all that small crap and can easy tell the surface trash and only dig the deep targets which is just nice sometimes.

The SL will work fine with big coils and Iv tested it, the SPP will also work with some larger coils if the conductivity switch has been added, using a single mode in Australia is most important think of ALL as the GB mode' LOW= Small coil & small gold, HIGH=Large coil & large gold, so you have two detecting modes but can only use one at a time.

You must GB first in "ALL", when you flick onto Low you turn the GB up a little to ignore the ground, when in HIGH you turn the ground balance down a little to ignore the ground (a little meaning 1/2- 1 notch)

Hope this helps

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Luke, Thanks for the report, So the man at GS was right it is possible to run the 20" coil on a TDI Pro, Have you had the chance to test the Two 14" MJ coils as of yet ?? the reason I ask is because I have the 12" DF but I would like a straight Mono and although I can import the 12" OZ Mono I think it would be a better idea to Buy the MJ 14" Mono so I am not Doubling up on the same size Coils,

NOTE, Luke I just tried what you said about Upping the Delay and you are Spot On it has no effect (If Any) on Targets weighing above 3/4 ozt ISH, I tried it at 10 and 15 to 17, And it does seem to have more effect in Low,

Thanks again Luke that's very helpful,

John

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John'

Yeah if done a lot of testing with the 14" round minerjohn/razorback' it will go up to 2" deeper on coin size targets and has very similar sensitivity to the 12" mono on smaller objects, just note the 12x16 MJD is basically the same coil just stretched out' but elliptical coils sharpen up the signal response.

Even though the weight factor is only just starting to creep up the 14" round and 12x16" elliptical would be all anyone would ever really need without getting too heavy and a handful to use, I use a bungy on the 12x16 and probably recommended but could be used with a control arm instead.

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Thanks for the feedback Luke. I'm sure you'll find some larger, deep gold & that is really the litmus test here. Those tips/settings will help many TDI users no doubt.

As I said though my interest in the TDI has waned to the point it's now off my radar & have since purchased another used Minelab machine for a bargain. Unfortunately the cheaper price of having another PI to play with was a real drawcard but the current exchange rate has made it difficult to go past a GPX4500 for around the same price as the TDI if I were to consider a new machine. The 4500 in my opinion/experience would suit me better for the price but that's not to say it would suit all. Old post revived too late I guess.

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  • 1 year later...

That is an awesome description of coil/filter interaction.

 

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I use a TDI Pro and not for nugget hunting but deep relic hoard hunting,currently the large coils that i use and dont have any problems with that are designed for the ML range are the 15x12 Mono,18'' Detech Mono,14x9 Coiltek and the largest coil which i will admit was designed for the TDI Pro is the 20' Grande Sierra mono.All run perfectly well,because i use it for deep larger objects i run my delay 15-20us.

Must admit not all that keen on the stock 12'' and 7.5'' DF coils that are made by Whites,infact they are basically brand new gathering dust as i just dont use  them,my favourite small coils are the Jimny folded mono and i think my all time favourite coil for the TDI Pro is the Coiltek 14x9 mono which was of course designed for the GPX range,but works extremely well on the TDI and exceptionally light as well because its foam filled.

When i use the Jimny folded mono with GB on and in low conductivity its deadly on silver hammered coins and roman coinage as well,but also hardly dig much iron,i have access too a roman trading villa site but what is mostly challenging about it are the ground conditions,the ground is basically nearly like black sand but about 80 miles from the coast,not alot of VLF machine can work this site but the TDI excels.

Really love this machine,maybe not the best machine for nugget hunting but terrific for my needs on some of my permission,its not used everyday but when it does come out to play it certainly earns its keep and the added beauty of a wide selection of ML coils.

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  • 4 months later...

I have been using a 25" Mono NF Advantage coil on my SL and runs stable with 10us and full gain. Very few times I get unstable operation and it is related to close by storms that also affect my VLF units. I did do a carbon fiber mod just in case.

Gilbert

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