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Tdi Pro Coil Comparison On The Goldfields


karelian

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I did a coil test some time ago using a Tdi Pro OZ, quite a variety of coils involved. Just a bit of information not wanting it to go to waste.

The test area was located in the middle of the Golden Triangle in Victoria, Australia. Looking at the images the test site is located on a area that produced large nuggets. Heavily mineralized to give the depth tests some authenticity. Targets were varied as were the coils tested. The Tdi Pro was ground balanced, gain was at 5, conductivity was in ALL, pulse delay was 10. Frequency was set in the middle and the audio was boosted by a Nokia MD-11 external speaker. Only clear repeatable signals were recorded.

All targets were buried in the ground sideway from a miners hole, so as not disturb the soil on the surface or above the target. Only the 1 grain ingot and one 0.5 gram gold coin were buried from the surface disturbing the ground.

Not sure how useful this is for Tdi SL users, deduct 10% maybe.. Just gives a sense of what is realistic is this one location at that one time with the Pro with the variety of coils available back then.

All the best, Karelian

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Just a few images to better show what is meant by mineralized ground. Run a magnet through this ground and it will be covered instantly. When I say nuggets found in this area, depth ranged from 4 inches to three feet and weights in the hundreds of oz. Diggers focused on the areas surrounding the 'monster nuggets' and turned their noses up at smaller gold in a nearby gully.  The area was rushed twice and has seen lots of attention from modern electronic prospectors. Nearby gullies still deliver little teasers whilst still hoping to find my own 'monster nugget'.

All coils ground balanced well on the test site, the only coil that was a bit difficult was the Whites 12' Duelfield, it balanced ok but ground noise was constant, useable but it wouldn't quiet down for long. The other duelfield coil was the Jimmy 10 x 6 as it was OK and better than Ok in milder soil. The Sadie was a stand out and both the Pro and SL love it.

 

 

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Awesome looking site.  Beautiful.  Thanks for the information.

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I recall your extensive tests from a couple years ago.  I used MS-Excel to summarize your results.  That thread is here:

Your posts back then prompted to me to search for (and find, for a good price) a used Sadie.  I've never regretted it for a second.  Glad to finally get to say "thank you" and glad you're becoming more active in posting to this forum.  Your input is invaluable.

 

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GB-Amateur, better display of results than I could ever manage, can't MS Excel to save my life. Must confess I obtained my Sadie second hand, just love good finds be they in the ground or in the classifieds. When I go into unfamiliar areas I always swing the Tdi Pro with the Sadie coil, it will let me know what is on offer and I have confidence in it's ability to pick up the small stuff and still punch deep.

Hopefully I can make both interesting and meaningful contributions going into the future, all the best GB-Amateur.

Karelian

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Just a question, if targets were buried, how did you alter the depths? 

Have you had an opportunity to test with some of the flat wound coils? When I did some testing with a customer and his TDI Pro Oz series, the 12" Evo and 14x9" Evo left a lot of the TDI specific Whites/Miner John coils for dead. Even the Detech 11" Ultra was very good, and still ran smooth. 

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PhaseTech, I didn't use any PVC pipe, what I did was use a short star picket combined with a hammer. I'd hammer the picket into the side of the hole, making sure to make a decent cavity at least 40cm deep into the side of the miners hole. This was followed by  wedging a pieces of sharpened flat wood with the targets firmly taped on. Maybe not burial in the traditional sense but it worked. Yes I did have to lift the coil up off the ground to get fine tuned depth measurements, but never more that 5cm,  anything higher and we'd just whack in another hole.

I had a flat enough surface or level ground and just had to even the side of the hole for accurate measurements. Only problem I had was targets near the surface, as the picket was a bit brutal and the ground would crumble.

Ended up having to bury the 1 grain ingot from the surface and one of the 0.5 gram coins. I'd swing the detector and my trusty assistant would do the measuring. Had to abandon the star picket and use my beloved soil knife for the other close to surface targets. What I remember most is that the process was slow and the flies were determined to drive us nuts. Not keen to repeat the process. There is something to be said for test sites and PVC pipe.

Karelian

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I haven't tried any of the flat wound Evo coils,  nor the Detech 11' Ultra. Last coil I ended up buying was the Detech 8 mono which impressed me a lot. Probably nearly as good or equals the Sadie on the small targets and has a small advantage on larger deeper targets. I suspect the round coil shape has a lot to do with that. I use it on the beach and in wet/muddy areas because that Detech is a solid little thing and waterproof, it gets all the dirty jobs. The Sadie doesn't see mud or water.   I'm in the process of culling coils at the moment and that will finance new technology. The mono 8' and Sadie are both keepers. Ground coverage and small gold sensitivity are a winning combination so I can see how the flat wound coils appeal. Karelian

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The White's Super Pulse 220 coil was intended by me for beach use only.  I was surprised that it performed  so well on the goldfields. Quiet and stable with good performance in hot ground. If you can get one it may be an excellent alternative to the 12 OZ mono.  Good size and not bad on smaller targets. No bump sensitivity or issues at all, very good all rounder. I remember White's sold these off at bargain prices in a sale, so there are some very lucky individuals out there who scored a bargain. I like it.  Karelian

 

 

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When I first got a Tdi it was a SL bought over to Australia from the USA by my brother. It came with the  Duel Field 12' coil, a Jimmy Tdi Dual Field mono and the mini Jimmy mono 6 x 4. The mini never saw any use, just too small and the big 12' was my beach coil for a long time. Everything else fell to the  10 x 6 Jimmy and it was my first choice on the goldfields until the Sadie came along. Never could work out how to employ the mini Jimmy, should I consider it as a probe to poke into a crevice? When there is so much ground that 6 x 4 mono looks so small and on a PI it didn't make sense to me at the time.   I think these coils were made for Jimmy by Whites?  Certainly rare beasts in Australia. Karelian

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