Reprinted from Gold Gem and Treasure magazine
(TDI PRO - discontinued)
I don’t think I’d win any prizes for guessing that there are quite a few people in the detecting fraternity quietly wondering how the pulse induction machine from White’s Electronics stacks up on the Australian goldfields. Well, after several weeks of testing. I have to say that the TDI Pro Oz Series is the goods.  It was taken to a variety of places with varying ground types and it passed with flying colours. In fact I was amazed to see that in one particular area I never had to adjust the manual ground balance once during an entire day’s detecting, and that includes upon start up.
Of course some places did require the occasional rebalance due to changing mineralisation and I encountered one very bad area that forced me to rebalance every 10 to 15 minutes but considering the overall performance, this wasn’t an issue. P-0The areas where I tested the machine are ones I’m very familiar with having trialled numerous detectors on them over the years, I find this provides a rock-solid platform on which to gauge a new detector’s ability.

The new TDI Pro Oz-Series will accept all pulse induction coils made by Coiltek, Nugget Finder and Minelab and after trialling just a few of the various sizes and shapes available, I settled on the Coiltek 14 x 9” elliptical mono for the purpose of these field tests.

I found this a great combination and the pinpointing of targets on the narrowed front end of the 14-inch was exceptional. As with any new machine there is always an unavoidable learning curve in getting accustomed to its particular operating features and the TDI was no exception. That said it’s not a difficult machine to come to grips with.
The first trial was at Tarnagulla and the spot chosen is lousy with false signals caused by numerous pockets of heavily mineralised and variable clays, many of which are of an opposing ground balance type to the ironstone-riddled ground that surrounds them. To date they have been impossible to completely tune with any machine I’ve used and I was keen to see how the TDI Pro Oz-Series fared under these conditions.
Well, after the initial ground balance check and a minor adjustment I was off and it became immediately apparent that the new TDI Pro Oz-Series was a different beast to its predecessor. Not only was it running with a much more stable audio but I was even able to increase the gain from level 5 which I’d used on the original TDI months earlier, to a new high of 8.
The clay pocket signals were still present but at a significantly reduced level of sharpness. Gone were the full-on signal sounds previously encountered here, replaced by a gentler mineral sounding entry and exit signal, the odd one still gave an occasional false alarm but the overall reduction in false signal occurrence was about 80%! Unfortunately I didn’t snag myself any gold at this spot but considering the difficulty of the ground and the flogging it’s had, I was happy with the overall performance of the TDI Pro Oz-Series.
Next on the list was a sport at Moliagul where some surfacing had been carried out on very hot ground. I had purposely left the ground balance settings on the detector unchanged from Tarnagulla site because I wanted to see how different this Moliagul ground was. Polar opposite would be an apt description with the TDI howling like a dingo gone mad when the coil approached the ground. A quick turn of the course then a bit of an adjustment of the fine ground balance control soon saw things nicely under control but boy did it show just how different two similar looking areas can be.
The ground at Moliagul was much hotter than the trial area at Tarnagulla and the gain control had to be lowered to around 6 to obtain more stable running of the TDI Pro Oz-series. As I covered more ground I encountered some areas that forced me to make minor adjustments to the ground balance every 10 minutes or so. Obviously underfoot there were some significant mineral changes taking place, highlighting just how bad the Victorian goldfields are and why machines that can cut it here can cut it anywhere.
Again I went unrewarded for my efforts but was pleased to see that the TDI Pro Oz-Series comfortably held its own in an area renowned as tough to hunt in.

The new White’s TDI Pro Oz-series fitted with Coiltek 14-inch elliptical mono and top view of the TDI’s control box.

The third trial was near Amherst. I’d been here a number of times over the years and found some really nice, clean looking gold in yellowish orange clay so I was hoping to pull a piece or two with the new TDI Pro Oz-Series, to prove it up. I decided to detect up the diggings a bit where the old boys had dug out some of the gold-bearing clays and rocks and left piled up portions of the poorer stuff untreated.
Upon start up I was surprised at just how quiet the ground was and I didn’t need to adjust the ground balance at all. I quickly detected my first target which turned out to be an old 22 slug that had probably been fired at one of the many rabbits that plagued the area a number of years back.
A short time later I got another signal that sounded the same and was expecting another slug but after I’d dug out about four inches of clay and stone, the signal was coming from a couple of bits of mangy quartz and clay. There was no bullet in sight so I dropped the conglomeration onto the tip of the 14-Inch mono and as soon as I moved a piece of quartz, the Pro let out a squeal that was unmistakable. It didn’t take much cleaning to reveal a nice little specimen containing a good show of visible gold.
The first gold find with a new machine is always a real buzz but it got better because five minutes later I had another bit, this time a clean bit of gold weighing about one gram.
I detected for another hour without luck and was making my way back to the car when I stopped for a breather and a drink near an old tree stump. I noticed the dirt and clay around the old root had pushed up looked similar to that which the old timers had dug out so I swung the coil half-heartedly over some of it and got a signal; soft and weak but definitely a signal. I dug out about three inches of clay near one of the exposed roots and scanned it.
The signal was there nice and clear and within seconds I had the gold in my hand. When I again waved the coil over the same area I got another signal which turned out to be a nice 2-grammer, in the end I finished up detecting an area about five metres square radiating out from the stump and wound up with seven more pieces of clean gold. None were big but the final weigh in was a healthy 11 grams.

Around 11 grams of gold from one field test was good day’s pay
especially at current gold prices.

My final test site was on a hillside not far from some old reef workings. I’d been detecting for about 45 minutes when I got a faint signal from a large bit of flat quartz lying in plain view I flipped it over but the signal still sounded the same. I’d left my geo hammer back in the car so I found a solid lump of rock and pounded it down on the quartz with my sunglasses pushed tightly into my face to protect my eyes. Fast flying bits of razor sharp quartz can inflict some serious damage.
More than once over the years I’ve gone to wipe away what I thought was sweat on my forehead after performing this task, only to be greeted with the sight of my own claret smeared across the palm of my hand. Sometimes you don’t even feel it.
Anyway, the smash out was successful and inside of one of the quartz bits was a nice sparkly bit of gold weighing about half a gram. As I made my way further up the slope I came across a pile of rocks the old timers has placed there while digging out what must have been a small costean.
I waved the coil over it and there was an unmistakable signal so I dug a few rocks out of the way and waved the coil back over the small excavation but the target was out. When I then passed the coil over a lump of mineralised quartz it screamed and I immediately got that tingle of anticipation you get when you know you’ve found gold.
There were a few cracks in this bit so an easy whack with the side of the pick quickly split it open to reveal some very nice looking rough gold inside some equally good looking mineralised quartz. Another pass of the coil over the pile produced another signal and in no time I was holding some smaller and finer gold in the same quartz type.
There were just a couple of grams in each specimen but they were two absolutely beautiful little keepers courtesy of the TDI. I was very pleased indeed. In summary the new TDI Pro Oz-Series handles our Aussie ground well. The occasional area can be challenging but no more so than with other machines. Its learning curve is not as severe as some with a week or two spent on the business end being all it should take for the average person to get handle on things. The availability of a huge coil range from various manufactures is a real bonus.
The TDI’s lithium-ion battery pack housed in the detector itself doing away with the need for back packs and annoying power leads dangling about and getting caught up and breaking.