Same test as above, changed the coil to the Jimmy Sierra Digger 14 x 8 mono, by Miner John. One final air test to follow before actual ground testing in the goldfields. These were air tests to determine sensitivity and threshold only. Tested were conducted with the same battery in both machines, same time and location etc. So the threshold component transcends into a bit more gain, an advantage in detecting whispers, with a bit extra sensitivity. Where the standard machine peaked at six, I got the modified unit to eight. A clear advantage to the modified machine. Also the ability to advance the gain or sensitivity before instability was checked. Threshold seems to be key here, actual sensitivity is very close, just a small fraction in favour of the modified machine. The unstable threshold works against the standard machine, I only record target depth as that which is repeatable and in my mind stands out as a target. The standard machine managed 4 cm whilst the modified Pro came in at 5 cm, marginal but still a 20% advantage. The quartz infused and partially porous gold sample is a challenge for PI machines, from testing I know the small Coiltek Tdi coil and the Sadie will pick it up. I suspect the smoother threshold makes it easier to pick up the target response but even taking that into account it was marginal. Both machines were tested on the one grain ingot, the modified unit beat the standard unit by 5mm or half a centimetre.
Tested small gold sensitivity and ability on porous gold using Coiltek Tdi 6" mono coil. Once it sold it will be too late to revisit. Any specific questions or suggestions, speak now or forever hold you peace. There is a process involved so I'll take my time and do it right. Some real small sub gram nuggets to see how small we can go. The 1 grain ingot, the half gram gold coin, a half sovereign gold coin. Test coils will be with a small coil and a large coil. Later I'll follow up with in ground testing on the actual goldfields in mineralized soil. I'll start with the usual useless air test. The machines will use the same fully charged battery pack, same coil, same targets, same test location and conditions on the same day etc. 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 opportunity to do a comparison cannot and should not be ignored. So the modified machine is probably not a keeper, I don't want two Tdi Pro machines. The specifics related to the modifications are not known by me, other than that they were conducted by 'Luke'.Oz Digger. My old mate had his machine modified to smooth out the threshold and to add some sensitivity. My machine is mounted on an Anderson shaft and is factory spec. The passing of a friend unfortunately has led to me taking ownership of a modified Tdi Pro.