Mark Gillespie

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.

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.

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.

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.

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.

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.

I used a calibrated, Fluke TRUE RMS volt meter for my measurements.

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.

These test were with a nickel approaching the coil, not simulating an actual sweep, right to left. I was listening for a slight increase in threshold. Still, I thought it did better than this. An 18 volt battery pack my help.

White's TDI SL, manufactured 2014, pulse delay 10 Air Test Freshly Charged Battery Pack GB OFF GB OFF GB ON MINIMUM GB ON MAXIMUM GAIN MAX GAIN 8 GAIN MAX GAIN 8 7 1/2" Dual Field Coil 11" 11" 11" 11" Super Pulse 350 11 1/2" 11 1/2" 11 1/2" 11 1/2" 12" Dual Field Coil 13" 13" 13" 13" To be honest I'm kind of disappointed Very smooth threshold In ground performance may be different

I have a couple videos on SL air test and hope to do some other comparative videos soon.

Can I assume your TDI is the TDI Pro with mods? My machine was bought 4 years ago and it is the TDI SL. Not sure if there are mods for mine that would give a performance boost as mention on yours. Thinking a true mono coil would give me extra depth in my area I purchased one form another member of a different forum. When it arrived I felt something was wrong, I contacted Carl and after his instruction on testing for mono coils it was obvious the coil was in reality a dual field and not a mono. A couple years back I remember reading about a mono coil similar to the one you described on your post. But never did know where they came from. All that being said the AQ seems to be on track to be a beach game changer.

Rick, I want to thank you for your post on the AQ. Last night I had time to actually ponder and absorb what you had to say about the AQ and the relationship between depth and discrimination. Then I compared your statements to my TDI and its depth/discrimination relationship and suddenly a light bulb came on. I've been picking and prodding other people that I know are involved with the AQ wanting just a little information and I only get silence. Well not exactly silence but they all would tell me that this machine would be a huge leap in PI technology performance. Yea, being a former tester I understand they can't say much, if any. I always made it a practice to be silent, even my hunting buddies didn't know what I was up to. Well enough of all the chit chat, to the point I go. If the AQ can deliver the same depth/discrimination as the claims, then it will be a huge leap. Still thinking out loud, if it can obtain a depth of 17" on a ring in the wet salt sand and also have the capability of discriminating out a nail or giving a different audio for the nail that would turn the tide (beach PI competition) My TDI, with GB off might only detect a ring in the wet sand at maybe 12" but would also give the same audio on a nail at that depth. On the other hand with GB on, my TDI would struggle to detect the same gold ring at 8" and that is a big maybe.

I've never been in the water with my TDI, coil wet yes but never deeper than 2-3". I enclose mine in a 3 gallon zip lock bag and only hunt the areas where the water has been. GB off and I dig it all. On occasion I'll dig some iron but not as often as most think. The reasoning behind my statement "Maybe faster recovery between adjacent targets." because in reality, since the sampling is quicker compared to, lets say 10-15, it will naturally have the capability to respond to more targets in a given sweep. It will be very interesting to see how this develops. But I can't image it will take over the market if the price is hovering around 2 grand. Now on the other hand, if there is a land version released with a good discriminator (I mean, discriminate nails and still hit on the high conductors) that would surly be a game changer, if not to pricey.

Rick, do you also agree the White's TDI has the capability to also see a gold ring covered by nails? Being an avid TDI user I know it can also sound off on a gold ring below a pile of iron nails. In fact, the nicest gold ring I've found was using the TDI in a nail infested area. If I'm reading the AQ features correctly it will offer a faster target analysis (pulse delay) over the TDI. Which will mean depth capabilities are greater over the TDI. Maybe faster recovery between adjacent targets. I think its already been stated it will be deeper than any VLF machine in the wet salt area. What other features that will excel all others? Why would a person want to buy the AQ? In hopes of finding gold on a beach where others have hunted and have missed because of excessive depth?

Thanks Rick,

There was a lot of free Minelab advertising came too. The people involved automatically wanted to know what kind of machine I was using and the cost. One gentleman asked several times to buy my machine. He stated it was a lucky machine, imagine that. Well, if Minelab sells a couple extra machines because of this recovery, that is good too.

Yes, I remember the last message he sent me explained he had a difficult time typing. Reading everything he posted about the PI machines, he is most likely the most knowledgeable (poster) that I know of. I'm sure there are some that might know more but getting them to post is another matter all together.

Does anyone know where Reg Sniff might be hanging out since Findmall removed the White's forum?

This being said I thought the first version of the AQ was for beach only use, sounds like they might be trying to squeeze a little inland potential with improved discrimination. But since there will be no ground balance feature I guess they are trying to improve the discrimination for the beach environment. It will be very interesting to see how it all pans out.

Well said Daniel. I'm in the same position. Many hours from the coast and I try to vacate the beach one week out of the year and I try to make the best of my hunting time while there.

Wow, I love digging nickels, most 10k ladies rings I've found fall at or below a nickel. Any war nickels in the bunch?

What an adventure. A lot to tell about the experience but short on time. Dug a lot of trash, nothing good but this. It's hard to put words to the happiness the family members are experiencing. ?

Steve, you are so eloquent with your words. I'm always inclined to read every word you post, ever learning and never becoming an expert at anything.

The only detectors I presently have are the Equinox, Fisher F75, White's TDI and Fisher F22. Maybe the F22 will be less sensitive to the fence. She only cares for my hobby when I bring something home that she wants.