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Mark Gillespie

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Mark Gillespie last won the day on July 22 2018

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About Mark Gillespie

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    Gold Contributor

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  • Gender
    Male
  • Location:
    Southern Virginia
  • Interests:
    Detecting and bird watching
  • Gear Used:
    Early (1980's) Bounty hunters, Tesoro Vaquero, Tejon, Garrett Ace 250, AT Pro, Minelab Explorer, Etrac, Fisher Gold Bug, F75, F75 LTD, F19, Whites TDI SL, V3i, XP Deus, Eurotek Pro, Equinox 800

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  1. Very interesting depth post. US nickel at 16" in the wet salt sand area. My SL can't come close to that even with the stock 12" dual field coil. It would be interesting to know a little more on the subject. Stock 12" coil? Pulse delay, 10? Gain? Frequency offset -, 0, +? Battery voltage?
  2. Very sad, they made some of the very best audio machines I've ever used. Very distinctive audio ID. Loved the Tejon.
  3. Add a battery holder and all is good to start. No more soldering wires to battery ends. https://www.aliexpress.com/item/2x-Battery-Box-Holder-Batteries-Case-for-18650-in-Parallel-3-7V-Pole-Black-Free-Shipping/32655188466.html?mb=45qWZRr1NV3W710%3Ftt%3Dsns_none&aff_platform=default&srcSns=Copy&cpt=1558372641975&sk=cdWWKWEU&aff_trace_key=f24da05d5b634cd194393ad869d2b975-1558372641975-00813-cdWWKWEU&businessType=ProductDetail&tid=white_backgroup_101&platform=AE&terminal_id=9f07fe2b09a04a87b33ec1bf896610cf
  4. Nice batteries can be found in used laptop battery packs. I found 6, nice batteries inside a HP laptop battery pack. All test good and can provide some nice project batteries. Some of the best on the market can be found in laptop batteries. A trip to the local computer repair shop can usually find some nice discarded batteries cheap. Brand: LG Model: LGEAS318650 (ICR18650S3) Capacity: 2200mAh Rated Voltage: 3.60V Nominal Charging: 4.20V Maximum 1075mA Standard 2150mA Maximum Discharging: 3.00V Cutoff 430mA Standard 4300mA Maximum Description: Blue Cell Wrapper White Insulator Ring 18650 Form Factor
  5. My SL was manufactured in 2014. Rechargeable battery pack was 11.62 v Fresh set of alkaline batteries in the Alkaline battery pack 12.61v I re-tested my SL this evening using the above battery packs and the 12" dual field coil. I saw, absolutely no air test difference between ground balance on and ground balance off. So, it would be obvious if I was hunting at the beach, to use the GB on feature over the pure PI function of GB off. At least I'd have some control over the iron and still hear the gold. Now I'd like to see other SL users post test results. Curious to see a date relationship to the depth reduction of ground balance on.
  6. Carl on the Getech just posted air test distances. 13+" all metal, 1-2" less in GB. I'm assuming this is with the stock 12" dual field coil and a nickel. This is right in line with what I've saw with the exception of GB on doesn't reduce my depth. I'll check again and confirm.
  7. auminesweeper Would it be possible for you to do an air test similar to the settings I mentioned above, using a nickel and quarter? I posted the same information on Carl's Getech site and he stated not having any idea about the GB question I posted. Makes me wonder, if White's knew something had changed but never revealed it to the users. Else I can't imagine Carl not having an answer but a reply, "Sorry, no idea what might be going on." I would bet Reg would have an answer.
  8. I guess the main thing I'm trying to figure out is why my machine's performance does not increase when ground balance is turned off. 100% sure of what I'm seeing now. I sent Carl a message but he's not replied and if anyone would know why, what, how on what I'm seeing, it might be him.
  9. I did another detailed test last night, using the TDI SL with the 7 ½” dual field coil with a freshly charged battery pack. Ground balance on and set to 7 ½, conductive switch set to all, gain max, smooth, low volume threshold. Results, two different tones, high tone for a nickel and low tone for a quarter. Air test, 11” for the nickel and 9 ½” for the quarter. Same settings but turning ground balance off, counter clock wise until it clicks off, conductive switch still set to all, one tone for both the nickel and quarter. Air test, 11” for the nickel and 9 ½” for the quarter. The same results were also noted using both the 12” dual field and the super pulse 350, no air test increase when switching from GB on to GB off. It is obvious this machine is different from others whom state gaining from 1-2” additional air test distance with the ground balance off. The manual also states, " Turning the Ground Balance to the OFF position disables the ground balance and TDI will run as a straight PI detector. This gives a slight improvement in depth but, of course, will respond to mineralization and eliminates the ability to discern conductivities. " All this being said, there must be at least two variations of the SL. You would never get White's to comment on this, for sure.
  10. I'm guessing you are correct. I'd guess the TDI's changed over time, as components fell to the discontinued status, substitutions were made. I'm doubting White's will provide any information but I'd still like to know why there are so many variations with the machine.
  11. Very interesting Jim. What device are you using to measure the voltage? I was using a calibrated Fluke True RMS and was measuring directly from the TX output on the board. All this said I noticed a very large difference in voltage from a complete counter clockwise frequency offset to a complete clockwise setting. Even though there was a large difference in output voltage I didn't see any extra air test advantage. The manual states this feature function is "This control makes small adjustments to the transmitter pulse rate". I was guessing a small shift in the frequencies and wasn't expecting the voltage span. Now you have me to wondering if the inductance of my coils might be different than yours because if the inductance is quite a bit larger (value) that would limit the current flow considerably.
  12. Sorry for the mistake, the first post had the 7 1/2" coil only getting 7 1/2" but it's actually 11" with a nickel.
  13. I used a calibrated, Fluke TRUE RMS volt meter for my measurements.
  14. I'm beginning to believe there are several different production models when it comes to the TDI. One might be obvious, the TDI Pro and the TDI SL. But from other users I think there are manufacturing variations in the SL model. About half the users I've conversed with state there is a huge depth advantage when turning the ground balance off, but that is not the case with mine. Speculating, the difference could be attributed to substituting TX components to coil specifications. I did some internal voltage/current experiments a few weeks ago and noticed one main thing. I could increase the standard input voltage entering the system but never saw a significant increase to the coil TX circuit (less than .010 volt) regardless of input voltage. I believe, in my unit, the voltage regulator might be preventing the use of increased voltage to the TX coil connection. This would explain the constant air test distances across the different settings.
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