The passing of a friend unfortunately has led to me taking ownership of a modified Tdi Pro. My machine is mounted on an Anderson shaft and is factory spec. My old mate had his machine modified to smooth out the threshold and to add some sensitivity. The specifics related to the modifications are not known by me, other than that they were conducted by 'Luke'..Oz Digger.. This happened some time ago. So the modified machine is probably not a keeper, I don't want two Tdi Pro machines.. The opportunity to do a comparison cannot and should not be ignored.
My intention is to focus on small gold performance, the threshold smoothness, the ability to use gain, basic performance and handling characteristics under different circumstances. The machines will use the same fully charged battery pack, same coil, same targets, same test location and conditions on the same day etc. Trying to minimise external variations. I'll start with the usual useless air test. Later I'll follow up with in ground testing on the actual goldfields in mineralized soil. Test coils will be with a small coil and a large coil. Targets will be gold only. The 1 grain ingot, the half gram gold coin, a half sovereign gold coin. Some real small sub gram nuggets to see how small we can go.. There is a process involved so I'll take my time and do it right. Any specific questions or suggestions, speak now or forever hold you peace.. I'm only doing this once. Once it sold it will be too late to revisit..
All the best.
Just arrived in the mail, Nuggeteer 18 x 6 mono, mounts nicely on the Tdi pro using a Minelab lower rod. It is weighty at 1 kg but easily balances on the Tdi Pro, just don't have any metal in your shoes..
When the weather clears I'll go down to the beach and give it a good run. Useless air tests, test garden results and beach run results in the very near future.. karelian
By Steve Herschbach
Very interesting....... https://www.usatoday.com/story/news/nation/2020/01/21/snowball-earth-oldest-asteroid-impact-site-discovered-australia/4531149002/
“Some 2.2 billion years ago, an asteroid slammed into the Earth, leaving behind a massive, 43-mile-wide crater in what's now Western Australia, scientists announced Tuesday.
It's the world's oldest known impact site, the new study said, one that also may have changed Earth's climate: It occurred at a time that coincided with Earth’s recovery from an ice age known as "Snowball Earth," where most of Earth’s surface was covered with ice sheets up to 3 miles thick, according to a statement from Imperial College in London.
The impact left behind a scar on the land that's known as the Yarrabubba impact crater. "The age we've got for the Yarrabubba impact structure makes it the oldest impact structure on the planet," study co-author Chris Kirkland, a geologist at Australia's Curtin University, told the Australian Broadcasting Corp.“
I've had this coil for quite some time, but it was packed away and forgotten. It was purchased for A$60 because I was intrigued.
It is the anti-interference version. Measures 12 x 4 and uses the MInelab lower rod.
Weight is decent, build quality is good. Performance in the field still remains a mystery as I've yet to use it. I gave it a quick air test just to see how it behaved on the Tdi Pro.
This version has a hot spot in the centre of the coil which appears very sensitive to small targets at shallow depth. Seems to hit fairly well at shallow depths but doesn't have much punch for the deeper targets. Test garden results on coins would give real world depth on coins between a solid hit around 15cm or 6 inches and fading fast past 20cm or 8 inches.
Useless air test with ground balance off, gain at max, in ALL, frequency in the middle, pulse delay at 10.
1 grain was 7cm
.5 gram gold coin 16cm
1/2 Sovereign 23cm
Us Quarter 23cm
Aussie Penny 25cm
Whites Buckle 33cm
So in summary it hits hard on small and shallow targets, the centre of the coil is a hot spot for sure.. Fades fast as depth increases, the big Whites buckle just managed 13 inches.
Since I managed max gain on the Tdi Pro in an EMI hot zone, the Anti-interference feature seems to work ok.. One of the things I like about the Tdi machines is the ability to plug in all sorts of coils, never know if you don't have a go.. My Tdi SL is highly resistance to EMI and the Pro less so but still very good. This coil could make more sense mounted on a Minelab around electric fences and mobile phone towers.. etc.
All the best,