Size discrimination with Pulse Induction machines?

[motherlode77]

Hey guys, I've been cache hunting for some time now, I had bought a Bulgarian PI that I have since gotten rid of, it would sound off loud on every nail and small piece, no good for my purpose. My question is, will a Pulse Induction machine discriminate out the small trash if you put a bigger coil on it? Say a 40x40" square? Am I better off getting a 2 box Whites or Discovery? Target would be gallon paint can size likely, between 1-3 feet deep (I seriously doubt any deeper than 3). Any input is appreciated, though it would be excellent if someone with a PI and large coil could weigh in or perhaps test their unit with a large coil, so see if it overlooks small trash

 

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[Terry Soloman]

Why not use a good VLF / Multi-freq? Paint can size targets show up with a 15" coil at 20"-27" and you can discriminate out a lot of the garbage.

 

[Tom_in_CA]

Motherlode77, your post/question brings up a good object lesson. One that I have been drum-beating on forum posts for cache-hunters (large objects) for a long time , whenever the subject comes up.

And that is : Exactly as you have come to find out: That even though it's true that various standard machines (coin/relic and various nugget machines) can get caches JUST AS DEEP (or deeper, in the case of pulse and nugget machines) as 2-box units, yet: The devil is in the details: You ALSO hear all the small stuff too. Thus perpetually digging holes for stuff you're not after. And even when the user tries to tell himself that he "will pass up all the small stuff by only digging the bigger beeps", yet he perpetually having to make judgment calls that drive him nutty.

Yes it's true that by using super giant coils (I'm talking the size of hoola-hoops) that.... yes .... they loose sensitivity to small stuff (coin sized) and still get big stuff. Thus mimicking a 2-box unit . I can not speak direct your exact question of various PI's when paired with super large coils. I'll let someone else tackle that. But I will say: Why not just use a 2-box unit, if they ultimate goal is that it's going to accomplish the same thing as using a hoola-hoop ?

And I would politely disagree with Terry's answer: A 15" coil is still capable of finding coin-sized objects. And, while yes, such-a-setup would do as he says on paint sized cans (and mimic depth of 2-box for large objects), yet, as said: The devil is in the details when you also can hear all the small stuff you are NOT after.

 

[motherlode77]

Why not use a good VLF / Multi-freq? Paint can size targets show up with a 15" coil at 20"-27" and you can discriminate out a lot of the garbage.

I actually had a CTX 3030 recommended to me, which I purchased. After field tests on test targets, I realized the thing could easily skip over my possible targets buried 16" or deeper, (I was using the 17" coil) also discriminating out iron would likely skip my target completely as its allegedly buried in a steel pot. I sold the CTX after it completely failed testing parameters. CTX is considered to be the best VLF. PI are much better at seeing deep targets in all soil conditions, the problem like I said is it picks up every nail or tack. So I'm thinking Whites TM 808 or a Discovery 900. But if anyone knows if a PI will discriminates out small trash with a large large coil, I would appreciate the input

 

[Tom_in_CA]

I actually had a CTX 3030 recommended to me, which I purchased. After field tests on test targets, I realized the thing could easily skip over my possible targets buried 16" or deeper, (I was using the 17" coil) also discriminating out iron would likely skip my target completely as its allegedly buried in a steel pot....

Yes. People will often point to standard machines. And they'll say it's "the best of both worlds" because you can go back and forth between purposes (individual coins AND caches) . And they'll point out that some standard machines, when used with large coils, and set up certain ways, can get the depth of a 2-box unit.

But as said in post #3 : The devil is in the details. However, I would disagree that the CTX can't be made to mimic a 2-box machine, if done correctly. For example, you could run it in all metal so you don't risk missing a large iron object at depth. But again: You'd be forever bedeviled by hearing all the small stuff.

 

[motherlode77]

Yes it's true that by using super giant coils (I'm talking the size of hoola-hoops) that.... yes .... they loose sensitivity to small stuff (coin sized) and still get big stuff. Thus mimicking a 2-box unit . I can not speak direct your exact question of various PI's when paired with super large coils. I'll let someone else tackle that. But I will say: Why not just use a 2-box unit, if they ultimate goal is that it's going to accomplish the same thing as using a hoola-hoop ?.

Tom, that's what I think I'll do, get a good 2 box, due to the junk in the areas I'm searching, size discrimination is the best bet I have.

 

[signal_line]

Don't buy that "won't hit small stuff" until you try it yourself.

The people who say they won't hit big stuff may be more accurate. LOL

 

[Tom_in_CA]

Don't buy that "won't it small stuff" until you try it yourself.
...

As you see, the OP and myself did "try it ourselves". And, even when thinking "I can just ignore small stuff and over dig the bigger signals" ......... it just never works out in actual application. Also: If you're talking places with carpets of nails and small stuff near the surface, you will never have an accurate mental gauge of big vs small at deeper objects.

And don't forget: big objects at depth can be a "whisper" and small object near the surface might be a "whisper". Thus better to have the machine that simply doesn't see the small objects FROM THE GIT GO .

 

[motherlode77]

So does anyone have a deep seeker PI machine with a large coil 36x36" or larger, and if so does it discriminate out small junk?

 

[Tom_in_CA]

So does anyone have a deep seeker PI machine with a large coil 36x36" or larger, ...

Is such a thing even made ?? That's like hoola-hoop sized (for those of you that remember this kids play-toy from the 1960s and 1970s). Why oh why would someone use a loop that big for md'ing ? To go deeper, while ignoring small stuff ? Then again: Why not just get a 2-box machine ?

 

[Carl-NC]

So does anyone have a deep seeker PI machine with a large coil 36x36" or larger, and if so does it discriminate out small junk?

I have a Detech SSP 2100, I used to have an Analog Systems 104B but it was stolen. They do not pick up small stuff.

I also have a TF900, TM808, and Gemini 3. Whether I would use a hoola-hoop PI or a 2-box would probably depend on what I'm hunting for and the terrain. The PI will generally go deeper and do better at ignoring small stuff but is awkward to use and not suitable in heavy brush etc.

 

[Tom_in_CA]

.... and do better at ignoring small stuff ....

Hmm, ok. I did find it a bit annoying when ... with the TM 808 .... when I was trying to get the most sensitivity (ie.: super tuned, holding close-as-can to ground, etc...), that I did begin to pick up stuff as small as domino sized objects.

My objective, in that particular hunt, had been cookie-jar sized objects we'd been commissioned to find. So I eventually found myself holding the unit a tad higher off the ground, JUST to avoid smaller objects, which were ALL OVER in this super junky farm-ranch yard.

 

[motherlode77]

Carl, what do you mean by "small stuff"? What size range about does it discriminate out?

 

[Carl-NC]

Been a while, but I think it basically won't pick up coins and smaller. That's a 1m coil. The larger the coil, the larger the target has to be.

When at White's, I had designed a TDI-based cache locator, mostly for myself as the company wasn't very interested in it. I had intended to team up with the guy in Idaho who makes the polyurethane blanket coils you can drag behind an ATV. Things didn't work out that way. Most PI's can be run with a large (1m) coil but you run into motion issues if they have an overly fast SAT. The SAT is usually easy to slow down. I think First Texas would like such a product, so maybe I should dive back in. I have way better ideas now than I had at White's.

 

[motherlode77]

Been a while, but I think it basically won't pick up coins and smaller. That's a 1m coil. The larger the coil, the larger the target has to be.

This would be either a paint can sized steel, or a glass jug of precious metal coins, it sounds to me like I need a 1m or larger coil. Would you recommend an even larger one? 48" or even 60"?

When at White's, I had designed a TDI-based cache locator, mostly for myself as the company wasn't very interested in it. I had intended to team up with the guy in Idaho who makes the polyurethane blanket coils you can drag behind an ATV. Things didn't work out that way. Most PI's can be run with a large (1m) coil but you run into motion issues if they have an overly fast SAT. The SAT is usually easy to slow down. I think First Texas would like such a product, so maybe I should dive back in. I have way better ideas now than I had at White's.

Wow, I am impressed and honored to be talking to a White's engineer. What kinds of motion problems do you run into with SAT speeds? Just out testing the TM 800 the other day, on buried copper to simulate something close to gold or silver, Fast SAT speed it barely picks it up at 3.5 feet, but it sings pretty loud and clear when I switch it to the Slow SAT. Why is this?

Also, in the TM 800 manual, it states that the machine will indicate over gold and silver while in Cave Mode. Is that true? Sadly the Cave Mode function doesn't work on my machine, I'll have to send it in, if White's still services that machine.

 

[Tom_in_CA]

Motherlode77: Do you mind if I interject here, and ask what the SOURCE of this treasure, you are looking for ... is ? Because anytime someone comes on here inquiring about machines that can do all sorts of super specific cache feats (rather than simply going out and looking for it): It's often-times some sort of legend or ghost story type thing. Eg.: they need a detector that goes 6 meters deep. And they have it honed down to a certain meadow or cave, blah blah

I hope I'm wrong, but.... It's starting to sound like this genre.

.... Would you recommend an even larger one? 48" or even 60"? ...

this is infinite in the answers. And is almost crazy to think about. How are you going to be going around with loops 48" or 60" ? If such a thing were even made ? Why aren't you going out there now, hunting with the multiple recommendations you've already been suggested ? Was there a problem with those, such that you need to come back with drawbacks to be solved ? Or will you forever be musing technology, without ever searching in the first place ?

.... Sadly the Cave Mode function doesn't work on my machine, I'll have to send it in, if White's still services that machine.

Caves ? Caves ? Wait : I thought you were looking for a metal object the size of a paint can ? Which is it ?

As far as the machine's ability to find caves, how do you know the machine isn't functioning ? Did you have a known cave, and the machine failed to beep ? Me thinks you're using it wrong. But what's the point in the first place , if you're looking for metal cache objects ?

 

[motherlode77]

Tom, I welcome comments, but I don't appreciate insinuations and bad attitudes.

No, this is absolutely not a "treasure legend" but something real and intimately known, due to the sensitive nature of it, that's all I will say here.

I'm not asking for a super machine that doesn't exist, but rather about using larger coils to discriminate out small junk, of which there is tons at the location I'm searching. I have been up there with several different machines, but it's an immense amount of digging, and especially as there is a network of roots all throughout. As I said, I have a TM 800 which performed well on tests (the best of anything I've used, surprisingly) in that it discriminates out small but goes pretty deep, though my test target gets faint about 3 feet. So if I go back and the TM 800 doesn't get it, I will next buy another PI with a large coil, and yes they make them (or make yourself, from pic pipe, very easy) and a 48" square is doable for one man, carrying strap on either side.

The reason I mention the Cave Mode is because the manual states that it will not sound on ferritic targets, but WILL sound on precious metal in this mode, so right there could be enough discrimination.

The reason I know Cave Mode doesn't work, is because I field tested it, in that mode it does absolutely nothing at all, even over drainage pipes etc, no sound.

Don't assume you're talking to an idiot.

 

[Tom_in_CA]

...
Don't assume you're talking to an idiot.

I apologize for my tone.

I have trained and tutored many people in my 40+ yrs. And have seen some of them, sometimes, complain of a "broken machine" or "disappearing signals", etc... Or ... like yourself, they go through 6 or 7 different machines and options to try out, because the prior one "didn't work". And sometimes, a mere 20 minutes on-site with the person, reveals solutions that were simply because of the way they were operating it. Or the sounds they didn't know how to interpret. etc.....

I could share some humorous stories (which could be analogous to your situation). But I fear we'd be getting "lost in the example".

Again, sorry for my tone.

 

[Terry Soloman]

YES, larger coils will walk over "smaller" targets but, the Coiltek 40" x 20" "Mothership" coil on a GPX 5000 will still hit on 1" x 1/2" canslaw.

 

[motherlode77]

I apologize for my tone.

I have trained and tutored many people in my 40+ yrs. And have seen some of them, sometimes, complain of a "broken machine" or "disappearing signals", etc... Or ... like yourself, they go through 6 or 7 different machines and options to try out, because the prior one "didn't work". And sometimes, a mere 20 minutes on-site with the person, reveals solutions that were simply because of the way they were operating it. Or the sounds they didn't know how to interpret. etc.....

I could share some humorous stories (which could be analogous to your situation). But I fear we'd be getting "lost in the example".

Again, sorry for my tone.

It's ok man, I do appreciate your input, as I've only been into metal detectors for the past 3 years because of this project specifically, trust me when I say it's difficult terrain, and I've been out there several times, I first took a Fisher 2 box out, but it was all over the place and it might not have been in proper working condition (could have been operator error, but I followed the directions to the T), then a Bulgarian PI, which had me digging nails and other small things into eternity, it's a bit of a trip to get out there so I like to make sure I've got the best tool for the job before I go out there, also I want to minimize the time spent there so as to keep down the odds of someone else getting curious (no I'm not doing anything illegal). I had a CTX recommended to me, but field testing proved it was likely to miss my target completely (at the probable depth) and so far this TM 800 has tested the best for depth and size discrimination, so I'm going out soon to give her a shot. I hope my reply didn't come off as too harsh, it just want you to know I am doing my due diligence and I'm not chasing a Mexican treasure story haha