White's TDI For Coin Detecting?

[Mark Gillespie]

Editors note: Mark contacted me regarding the use of a PI, specifically the White's TDI, to try and get better performance on coins at a difficult location. I asked him to post here to get the ball rolling on the subject - Steve H
 
The reason I'm asking these questions is because where I live all the old schools used coal for their heat source. After burning the coal the waste was spread out over acres of land to get rid of it. Most is the size of a bb up to maybe a small marble. It is some sort of iron makeup because it attracts to a magnet fairly easily. And as you well know a regular VLF machine is rendered about useless with the exception of very shallow targets. Over the past 7 years I have owned or borrowed each of the following machines and none can get any depth over 4" in these areas. The following is a list of the machines. Tesoro Vaquero, Tejon, Lobo Supertrac, Garrett A250, Teknetics Eurotek Pro, Fisher Gold Bug Pro, F75 and the LTD version, Whites XLT, DFX, V3i, Minelab Explorer SE, Etrac and CTX 3030. Please keep in mind, not all the machines were mine. Some were loaned to me just to try in this bad coal cinder ground.

One interesting note about the Minelabs, when auto sensitivity is used the machine will throttle down to 8 or lower in these areas. Now you might be wondering why I'm so interested in this one particular area well it is because it was one a huge group of ball fields used back in the 40's right on up to the 70's. I have pictures of actual ball players and at times there were hundreds of people watching games. Now that said, there should be many silver coins at this location, but none have been found and I can only guess it is the ground. Because over the years we have buried coins at 4" deep that none of the machines mentioned earlier can detect and 4" is not deep for any of these machine. So my assumption is that the material robs the transmit signals from the machines to the point depth can not be achieved. I have talked to Carl at Whites and Dave at 1st Texas about these extreme harsh locations and actually sent them each a 4 pound box of this material to test. Dave suggested ground balancing to the material and using the motion all metal mode to hunt. This provided some positive results, but only to about 5" in depth. On the other hand Carl was working on a PI prototype at the time and could only provide his comment, which was, no VLF would be able to perform at these locations. After reading many of your post and watching your videos I decided to contact you for additional information. I sent Carl another message after reading about your postings on the Whites TDI and here is his reply.

Re: dirt
Quote Originally Posted by markg
Carl, a guy that hunted the digging in Virginia swears that the Whites TDI will punch through this kind of dirt. I know you can agree or not on this subject. But the cost of buying one to try would be a gamble. What do you think?

Quote Originally Posted by Carl-NC
just tested your cinder soil with a TDI... it's actually pretty mild compared to my Australian soil. The Oz soil is strong and has a very tight ground balance setting, whereas the cinder soil is weaker and has a broader GB range. So I think the TDI would handle this stuff easily.
Regards, Carl



I guess I really would like someone close to where I live visit and try a pulse machine. That way I would know. I can provide an open invitation to hunt about any evening.

[Steve Herschbach]

Hi Mark,

Thanks for joining the forum and posting.

When I got involved using the pulse induction detectors one thing became obvious, and that there was a lot more uses for them than just nugget detecting. I started making posts about using ground balancing pulse induction (GBPI) detectors way back before it was common to use then for anything but prospecting, advocating that they were a secret weapon waiting to be used. See Coin Detecting With The Garrett Infinium and Coin Detecting With The Minelab GP 3500. 

In my mind it is all about desirable targets and them being depleted over time. While finds are easy VLF detectors work just great, especially in low to moderate mineral conditions. I thought it was obvious though that good finds were getting harder over time due to years of detecting. It was also obvious that many good finds remained in areas where VLF detectors suffer, basically anywhere adverse ground conditions exist.

I figured it was only a matter of time before people started turning to GBPI detectors to tackle these difficult sites. All it takes is potential finds worth digging junk for, and at the end of the day that means almost anything. I heard from lots of naysayers that it was just not feasible, that PI detectors made you dig too much junk. Indeed that is true, but when a location plays out with VLF detectors it is played out. You either move on to new places, or pull out the stops and just keep digging.

The beach guys and the relic guys both got in the earliest. Beaches are easy digging, so digging trash is less a burden than other places. Garrett and then White's lowered the cost of entry with the Infinium and TDI, and that got the ball rolling. The relic hunters back east caught on quick and Infinium and TDI detectors became commonly used. And in the inevitable quest for more power people even started bringing in the more expensive Minelab detectors.

High value targets like jewelry on the beach and valuable relics make it a no-brainer and it was bound to happen. The only real difference with coins is the relative value and desire on the part of the operator to dig junk for coins. In turf locations the obvious need to dig as few holes as possible also comes into play.

The bottom line is it is all about site selection. If a location has bad soil and is potentially hiding good coins, and digging lots of holes is not an issue, than a GBPI detector can produce the goods. My preferred unit for these use is still the White's TDI, followed by the Garrett ATX. The TDI has the magical Target Conductivity switch that eliminates the vast majority of the signals that are likely to be junk. The Garrett and Minelab detectors force you to listen to all signals and that means a lot of listening and mental sorting. The TDI is far less wearing as all you have to hear is the rare low tones most likely to be copper or silver coins and unfortunately, large ferrous junk. It is an inherently quieter unit anyway. The ability to manually tweak the ground balance control also lets you fine tune what targets show up as low tone targets. I try to get set up to where zinc pennies do not signal which can usually be done with no real loss of performance.

My main concern in your situation Mark is you are saying this location has not produced any old coins. I would much rather you said it did but now none can be found because the VLFs are only getting the shallow ones. I target areas where VLFs did good but which have played out of shallow finds. In other words, people have gave up on the locations with VLFs and have moved on. If the location is highly mineralized, deeper coins are almost sure to remain for me to find.

But in your case something else is at work. No good find in the top 4-5 inches. Why is that? Were the grounds buried with new topsoil at some point? Or bulldozed off? I can hit a dime up to 10" in bad ground with a TDI, but you have no way to know if that extra 5" is going to pay off or not. Like you say, it is a gamble.

If you are looking for someone to give it a go first I guess all I can advise it you hit every detector club within driving distance looking for a TDI owner, or maybe an Infinium owner.

I just updated my TDI coin digging tips at Steve's Guide to White's TDI Coin Settings in case it can help. I plan to do a lot more of this now that there are 1800s coin all around me. It never was a big priority for me in Alaska where pre-1900 coins are almost unheard of. The TDI is my go-to detector for this particular quest.

[Mark Gillespie]

Thanks so much for the added information.  I find it hard to believe this area doesn't hold a lot of goodies, just out or reach.  I have pictures of many people playing ball and huge crowds of people setting and laying around watching the games.  I could be very wrong about the potential, but it just makes sense to me.  Thanks again.  If they ever dozed the top, just a few inches I'd know for sure.

 

[deathray]

Very detailed and informative Steve. I think I will give it a try at dome Stockton parks we explorered to death.

[Steve Herschbach]

Ray, you know the old question, "how do you eat an elephant"?

One bite at a time.

It is all about the site. If the site had the goods and no VLF made is producing any more, what is there to lose by trying? I hate digging deep holes in turf so I will only put a few in any given area over a period of time. So just cherry pick a few of the best sounding soft, mellow targets. They may be nothing but old rusted square nails. If nothing else I figure removing them may unmask a good find. I know one thing for sure. I like pulling a single good find out of a place everyone else has tried and given up. Gives me a warm fuzzy. If a site is good, why not clean it out? But it can't happen all at once. Just take small bites.

[fredmason]

When the first version of the TDI came out I was able to borrow one from a buddy. I set it up per Reg Sniffs directions and was amazed that i was able to get copper pennys and a late 1800s silver dime without digging pulltabs and iron bottle-caps...

I am sure the newest editions are way better...

Now I am in love with my CTX3030...Mark;if the 3030 you borrowed  did not work in that ground you may have not been setting it correctly...like most detectors experience is key.

fred

[Steve Herschbach]

Hi Fred,

I can easily hit coins in bad ground deeper with my PI detectors than my CTX will go and still get an ID on them. But the CTX is a real sweet machine and far, by far my preferred detector for turf detecting. I always worry about discussing the use of PI detectors for coin detecting as somebody decides they are some sort of magic super weapon and runs out and buys one. It seems no matter how many times I mention that you are going to dig large ferrous junk people then complain about digging large ferrous junk and how a PI can't work blah, blah, blah. Good detectors like the CTX have really spoiled people. When I got into detecting there was no such thing as discrimination. It had not been invented yet! I have a really high tolerance for digging trash targets. People that do not want to stay away from PI detectors.

"I am sure the newest editions are way better"

Nope, not a bit. You have a couple different flavors of TDI now but no big changes since 2008 in what they actually do.

[fredmason]

The trouble is that people will "hear" the parts they want to hear and ignore the rest of the story...especially when someone with your credentials speaks.

My first Garret was a Tr/vlf...the Tr mode was useless until some smart person developed the Reverse Descrimination technique. Before that I had to pay attention to the sound and size of the signal which was actually a very good method...now, I have gotten pretty lazy compared to my 1980 detecting days...

I agree a PI will go deeper than anyother detector...But, God save the parks when some nubbie gets loose with a pi in them.

 

fred

[Mark Gillespie]

The CTX was used by my hunting buddy.  He has about a year experience and has been beating my butt with finds.  He tried every possible settings.  Finally he opened the screen completely and ran with a manual sensitivity of 28 and could only get tick on a 4" dime.  I know it is hard to believe, but we both know a PI has to be the next machine for one of us.

[Mark Gillespie]

What about the detector pro PI machines?