I read your forum post yesterday and could have answered it based on my experiences and what I believed to be the correct answers, but instead I used it as a good excuse to grab a couple of rusty nails and my ‘Test Tube’ and head out detecting for the day.
I got back in town and stopped to order a pizza-to-go for dinner, and while waiting I started dealing with crashing blood sugars and had to deal with that and getting my diabetic frustrations under control. By the time I did and got home, I just enjoyed some excellent pizza and then got some rest. I wasn’t feeling up to posting the reply that I am doing now, so pardon my tardiness. Then today I started it, but have been handling phone calls that have interrupted my slow typing process.
I own and use two Makro Racers, now the main part of my Primary Use Detector Battery that stays on my back seat. I have the small 4.[size=small]7[/size]X5.[size=small]2[/size] DD coil mounted on one of them and the solid 5½X10 DD mounted on the other. I also have the 2 two standard 7X11 DD coils, an additional small coil and the larger 13.[size=small]3[/size]X15.[size=small]5[/size] DD coil that all travel with me in an accessory tote in the trunk.
To make sure I compared all the targets as you requested, I did it with the small, medium and standard DD coils. I didn’t do it with the largest coil. In my 'Test Tube' I have a number of good targets and an ample number of unwanted trash targets making up the '50' hidden-from-view samples.
One is a good old Beaver Tail type Ring Pull tab that is complete and with the 'tail' pointing straight out. Another is an older type Ring Pull tab with the Beaver Tail bent so that it curls around inside the 'ring' portion. I had several nails in my seminar demonstration samples and I used two of them. They are about index finger length, but have different thicknesses.
Tom_in_CA said:
A buddy of mine just shelled out to get this "latest greatest" Racer. I ribbed him for awhile, saying that it was all just "latest greatest" hype, that accompanies any new machine that comes on the market. But within a year, they're all just ho-hum normal machines. Not as capable of super-human feats that all the initial rumor-mill-buzz scpeculated about !
And when you look back at the history of the internet forums, for each time a new "latest greatest" was introduced, they were also accompanied by bullet-proof videos, testimonials, blah blah . But in time, they'd fall into a regular class of detectors, nothing super human afterall. Doh!
Yes, you're kind of correct and that even applies to those Malaysian-made detectors for the Australian detector maker, Minelab, that also came with a lot of touts and praises … initially.
There are several comments I have used for decades now when discussing detectors and helping others in their search for the right one for them, or learning what their might have. One that has been true for decades, is spot on correct today, and will continue to be forever, is this:
“
There is no such thing as a perfect metal detector.”
It is up to each of us to learn what is out there, learn the site environments and challenges we will deal with for our choice of hunting, and then learn what a number of metal detectors can and can't do, making it easier for us to select one or two that we feel best fit our needs and site environments. If your buddy gets a Makro Racer Pro Package, providing him with the small coil as well as the standard 7X11, then all he needs to do is:
Be patient. Learn its features and the best operating techniques. Master it.
I guarantee you that your buddy will then have in his hand one of the latest detectors, and will then know, also, that he has one of the greatest detectors for a wide-range of detecting applications.
Naturally it will depend upon the types of sites he prefers to hunt, but for me, where I usually try to hunt iron plagued urban renovation or get away to ghost towns or other iron nail infested sites, the Racer is about the best all-around performing detector I have ever used.
Tom_in_CA said:
While I recognize that someone can 'diss air tests , and say they serve no purpose, yet I disagree with that. They are beneficial in knowing a capability. For example: if you can perform a test in the air (for depth, or masking, or whatever), then at least you have a "fighting chance" to replicate that same feat in the ground, eh ?
Correct. Air Tests might not be the best to use, but I like them as we can get a general idea of what a detector and coil combination is capable of under almost ideal conditions.
Tom_in_CA said:
So with this in mind, can a couple of you do the following air tests, and report back your results:
a) set the machine's disc. to *just* knock out finger-long sized rusty nail. So for this test, we will not be using the full-spectrum tones (where the user relies on his ears to discern iron versus a conductive trying to peak through). I'm assuming the Racer can be set to do this, right? Where you can elect to have iron null out, rather than give a tone?
Clarification for some readers regarding terminology: Tom asked to have the iron nail "null out." With the older, traditional TR-Disc. detectors, you hunted with a Threshold audio and any accepted target would produce an increase in audio from the Threshold [size=small](aka a 'beep' today)[/size].
If the target was rejected … Discriminated … then the Threshold audio would get weaker, even to the point of completely 'nulling' or going silent. Some makes and models on the market today, such as the White's MXT Pro, can operate with a Threshold audio in the motion-based Discriminate mode.
With such a model you can sometimes hear a nulling when you encounter a Discriminated target, but not always because many of the Threshold audio Discriminate mode detectors have a fast auto-tune that counters the nulling audio. The Discrimination circuitry handles rejecting an unwanted target but you don’t always hear it cause a ‘null’ effect.
Most detectors models today, and for quite a few years, operate in the Discriminate mode as "silent search" models. By design, you do not hear a Threshold audio sound during the search. Therefore, you cannot hear a 'null' response because there is no functional audio to null from.
Instead, you only hear any target that produces an audible response [size=small](a fixed audio 'beep', a different static tone 'beep' based upon the target’s conductivity, a VCO enhanced 'beep' or a blend of these)[/size] based upon the target conductivity, size, shape and influence on the EMF of a target that responds higher than the Discriminate rejection point.
To Continue: So to address your 'a' request, I adjusted both of my Racers to an ID Filter [size=small](Discrimination)[/size] setting of '23' which just rejects my two sample Iron Nails as well as the four iron nails on my
Nail Board Performance Test [size=small](comments on that to follow as it might apply to Tom’s overall goal)[/size].
I did this with both the 2-Tone mode and 3-Tone mode to just barely reject the Iron Nails.
Tom_in_CA said:
b) Then take a dime, and hold it behind that nail. Wave it. Does the racer still null ?
No, because as I just described, there is no functional audio Threshold to hear a 'null' from.
If you were to ask if the Iron Nail rejects or impairs a response from the small Dime coin, that answer would be Yes, some of the time, and No, not all of the time. The important point to know the correct description of the answer would be:
If the Nail and Dime are swept across the center-axis of the search coil as if encountered
length-wise, then
No, you will not get a good audio response on the Dime due to the influence of the ferrous target on the EMF.
If the Nail and Dime are swept across the center-axis of the search coil as if encountered
cross-wise [size=small](with the head and point of the nail pointed to the front-and-rear)[/size], then
Yes, you will get a good audio response on the Dime.
Tom_in_CA said:
Or is the target combination now strong enough to up it into the accepted range now ? Yes I realize it's not going to give a "dime" TID, of course. But is it enough to cause the machine to get a positive signal?
The “combination” isn’t really upping a response for the Dime, when it is able. The Dime is able to respond because with a crossing sweep instead of a length-wise sweep, the Iron Nail is not degrading the EMF as much and the Dime is able to be responsive.
The problem with this test scenario is that we are dealing with Iron, a ferrous metal target, and a Dime, a smaller-size and non-ferrous metal target. Even if the two targets were of similar size and shape, but of the two different metals, the results would not be the same due to the different effect of ferrous/Iron on the EFM than what a non-ferrous metal makes.
Ferrous targets have a greater effect, and different effect, than a non-ferrous target of similar or smaller size on the EMF. That is what makes hunting in an iron infested site so difficult. The greater influence of iron, combined with it being rejected and the challenges of the circuitry to process the greater iron influenced field of the rejected target for today’s modern, motion-based Discriminators, has to be learned and appreciated.
Tom_in_CA said:
c) Now try the same test with 2 nails over a dime (making sure that the disc. setting is *just* enough to knock out those 2 nails, when detected held together).
No, the Dime is likely to NOT produce a positive audio response, regardless of the direction of the Nail and Dime presentation to any of the search coils simply due to the greater negative effects of the rejected Iron on the EMF, since there is now more Iron.
Tom_in_CA said:
d) try the test with the dime held touching the nail(s), versus separated by a finger's width. Any difference ?
Yes, the difference is
No, the Dime is likely to NOT produce a positive audio response, regardless of the direction of the Nail and Dime presentation to any of the search coils simply due to the greater negative effects of the rejected Iron on the EMF, since it is closer to the coil, combined with the now-deeper [size=small](and farther away)[/size] smaller-size Dime.
Tom_in_CA said:
Note: I ask that this test be done with the nails to be a "null" (silence) , rather than the full-tone ID. So that there can be NO MISTAKE on whether or not it's truly bumping up the signal enough to over-ride the iron.
As stated, I used an ID Filter setting of '23' on both 2 and 3-Tone operating modes to barely reject the Iron Nails so nothing was heard from them.
Tom_in_CA said:
Because it's far-too-easy, when relying on supposed differences in tones, to say "I'd recognize that something is hiding amidst iron". When, in fact, when you get into the actual field, it turns out that those same squeeks and squaks are HEARD EVERYWHERE. Doh! Not that I wouldn't hunt in full-tone-ID mind you. But just that for air-purpose testing, there can be no mistake of judgment calls of what constitutes a signal, versus what doesn't.
Correct, and there are many times, if the Iron Nail level isn’t too dense or severe, I will hunt at the default ID Filter setting of ‘10’ because that helps let me hear ALL targets, both ferrous and non-ferrous, and then I can test my own skills and classify Iron targets and work the coil around them to try and find a partially-masked keeper.
Tom_in_CA said:
Next Racer air test please:
This would be for applications where someone is, perhaps, getting ready to hunt under grandstand bleachers, or junky parks where they're going to angle just for high conductors amidst a sea of tabs and foil:
a) Set the Racer to *just* knock out round full tabs w/beaver tails intact. Such that it nulls (hence we're not going to try to rely on ears for this either).
Okay, I did that for both the full Ring-Pull tab with attached Beaver Tail sticking straight out, and also for an older Ring-Pull Tab with the beaver Tail bent to curl around inside the Ring portion. ID Filter was adjusted so they were just barely rejected and I couldn’t hear a response from them.
Tom_in_CA said:
b) Now holding a dime behind a tab, does this cause the Racer to bump up the TID, to the point where you now get a signal ? Granted, it won't be a "dime" TID, but .... positive above the tab setting, none-the-less.
Nothing really “bumped-up”, just a situation where the Ring-Pull tab is rejected but the Racer DOES respond to the Dime, even with an incorrect Target ID number reference.
Tom_in_CA said:
c) try the test with both dime touching the tab, versus held a finger-width's space.
Yes, I still got a responsed, Ring-Pull Tabs rejected, Dime just touching and under the tab and away from the search coil.
Tom_in_CA said:
d) try the test with 2 tabs covering the dime (first making sure that 2 tabs, with no coins, are disc'd out nulling).
Did it with the 2 Tabs and then added the Dime. Still got a response that, while not a proper audio or visual response, was a 'dig me' target hit.
Tom_in_CA said:
e) Do the test with both small coil, and large.
thanx! Tom
I did it with the small coil, the 5X10 solid coil and the standard 7X11 coil, using two Racer's to double-check the results.
Added Note about Hunting in a Dense Iron Nail Environment: Tom, your "air test" was done that way as well as with targets laying on the ground. I have done these tests so many times by myself to evaluate detectors, and also with others who helped me cross-check different hunting scenarios.
There have been many different test scenarios I have tried, and naturally, hunting ghost towns since May of ’69, I have encountered an endless array of Iron Nail conditions, many quite different, but I have noted one thing in particular.
Most of the time, when I have found Trade Tokens, Coins and other smaller-size 'keepers' in iron nail infested sites, the good targets were close to nails. Often on the same plane, and close to the Iron Nails. Yes, sometimes over or partially over the Nails, and sometimes under or partially under the nails, but most were just close to Nails and not directly centered under the Nails.
On Memorial Day Weekend, the end of May of ’94, I encountered four Iron Nails on top of the old school hill where there wasn’t a structure remaining, but a very dense amount of scattered Nails. In the center of the four Nails was an Indian Head cent. A lower-reading coin than a Dime thus a little more of a challenge.
I asked several others hunting nearby to come and try their detectors and coil on the Indian Head cent and four Iron Nails, all laying in plain sight. No one was able to get a single response to the IH cent from four indicated directions, with a side-to-side sweep, making 8 possible target responses.
The only detectors able to get a satisfactory number of responses that day were all of the Tesoro models present, most using a 7” coil, a White’s Coinmaster Classic II, and a Gold Mountain Technologies GMT-1650. All of those detectors hit in the Indian head from all four marked directions.
I made a copy of the exact position of the nails and coin and picked them all up. From that I made an exact copy to produce my first
Nail Board Performance Test and, to this day, almost 21 years later, it remains the best all-purpose test scenario to evaluate detectors and coils to hunt in a dense Iron nail environment.
Detectors from across the USA and many competitive detectors from countries all around the world have been put to the test on this scenario.
For all practical purposes, for hunting tough sites, I have found it to be a more reasonable way to evaluate detectors and coil, and their ability to reject Iron nails and respond to [size=small](or not respond to)[/size] a centered coin.
Send me an e-mail with your mailing address and I’ll get a NBPT kit to you.
Monte