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A consolation prize? .... Never thouht of that, but here itn is:

September 23, 2018 11:17AM avatar
The Consolation Prize is another lengthy post to explain things related to why some detectors work, some kind of work, and some don't work too well. grinning smiley


Quote
Hombre
I have heard good things about the old 100 kHz Transmit Receive instruments but never used one.
Going 'back in time' is often fun to do. A few times every year I will take a trusty old TR along with me and put it to work for at least a short while at some old site. Memories of those good times of the first decade I was enjoying this sport. BFO's I started with, then progressed to TR's. Just straight TR operation before we had TR-Discrimination, and most of those earlier TR's worked at or closer to 100 kHz.

The incorporation of variable Discrimination was still with most detectors working at that higher operating frequency, but many TR-Disc. models early on had too much Discrimination or Rejection even at their minimum Disc. setting. That caused some operating challenges and it was the straight TR function, w/o Discrimination, that did so well in typical iron nail infested sites.

Handling nails, not all types and sizes of iron, just dealing with scattered nails, was pretty easy for most conventional TR's to handle, and the only operating technique you had to master with those early detectors was adjusting for a proper slight-audio Threshold hum AND maintaining a fairly consistent coil-to-ground relationship. When you tuned those early Metal/Mineral Locators or the other design to just be a Metal Detector, the unit is going to be reactive to the presence of any metal object, ferrous or non-ferrous, that is close enough to have an effect on the EMF (Electro-Magnetic Field).

That can be a coin, trade token, metal button, foil, ring, bullet, buckle, or a ferrous object such as a nail, bolt, iron wire, other similar-shaped objects and ..... ground. Yes, ground was a challenge because most ground is made up of some amount of ferrous-based dirt, sand, gravel, decayed rock material, and other forms of magnetic mineral properties.

If Coin Hunting a very level terrain of uniform ground make-up, and the grass was just mowed at as 2" height, you would adjust the Tuner for a proper Threshold level hum with the search coil just on the top of the mowed grass. Then you could search the site and maintain a uniform coil-to-ground relationship by keeping the coil working at that 2" grass height. If you came to a bare patch of ground without grass and lowered the search coil from that 2" coil distance down closer to the ground, you would be putting more ground mineral into the stronger portion of the EMF and that would cause the Threshold hum to decrease or usually null out and go silent. It wasn't tuned for that amount of negative ground mineral effect on the search field, so you would have to either raise the coil back up and maintain that 2" distance from the ground, or re-tune the Threshold setting and then maintain that new search coil position to continue hunting.

However, if you encountered an area where the grass had not been mowed and it was 4" tall, and you raised the search coil away from the ground from 2" grass to 4" grass, the audio would increase a lot and get loud. The reason? You had now lifted the coil farther away from the ground and therefore the ground mineral content is having less effect on the EMF and is only effecting the weaker and more distant portion of the field. You then had to either move the search coil back down to the 2" working height you originally adjusted the Tuner at, or you had to readjust the Tuner to restore a proper slight audio Threshold hum.

Ahhh, those early years of simplicity that required more operator awareness and coil control in order to find all the good stuff that was out there. Obviously using a TR or TR-Disc. model in the '70s called for a person to have more patience, and that was especially true when hunting sites without flat ground and nicely maintained lawns. Or locations that also seemed to have a greater amount of ferrous trash present, to include nails but other magnetic-based debris.

Uneven or rough, rocky terrain such as ski slopes or sledding hills was a challenge. I was using a non-discriminating BFO when my brother Ed & I first worked a ghost town in northern Utah that I named 'Twin Flats' in early May of 1969. I moved on to using TR's most of the time in May of '71, and continued to keep a good functioning TR in my detector outfit even after we progressed to using VLF and VLF/TR-Disc. models in '74/'75.

For newcomers to the sport, VLF technically refers to detectors operating in the Very Low Frequency range of 1 kHz to 30 kHz, but when first designed for the recreational metal detecting hobby in '74, these detectors were still using the TR operation but at the much lower frequency, and this new design let the design engineers incorporate an additional control to counter the effects of the ground mineral influence on the EMF. The first was from White's where design engineer, George Payne, developed the hobby's early ground cancelling model where the operator used two controls to set the detector up.

One was the Tuner, the proper name for the control used to adjust or 'tune' a proper Threshold hum, and the other was called a Terranean Attenuator. That control let you attenuate the signal from the terrain. It took a few moments or so, and patience, to hold the coil a foot or so away from the ground and adjust the Tuner for a Threshold hum, then lower the coil to the search height and adjust the Terranean Attenuator to restore the Threshold for the ground mineral influence on the EMF, then raise the coil up and counter-adjust the Tuner, lower the coil and work the Terranean Attenuator control, and do this several times until you could raise and lower the search coil from about 1" up to about 8" to 12" and maintain a consistent Threshold audio.

Needless to say, the term Terranean Attenuator was a mouthful for people to say, and all of these models from White's then Garrett and the other makers were initially called 'VLF' detectors because:

1.. They operated in that 1 kHz to 30 kHz Very Low Frequency range, and

2.. That described their ability to discriminate or reject the ground mineral signal.

The VLF mode of operation was initially great for many Relic Hunters who wanted to find everything, ferrous or non-ferrous, because once you adjusted for a workable Threshold and adjusted to ignore the effects of the ground mineral signal, you could work the coil over rougher terrain and lift it over a rock, pine cone, weed or other non-metal object and not have the falsing of a conventional TR. Thus, you then ignored the ground signal but got a response from anything out of context (different from) the ground ... and that meant fining basically ... everything! Iron, lead, copper, brass, silver, gold, aluminum, just about any metal object.

Therefore, a VLF detector, or the new VLF design, referred to an All Metal search mode. And the different manufacturers soon started using their own terms to describe the new control used to cancel out or ignore the effects of ground mineralization, such as:

GA for Ground Adjust
GB for Ground Balance
GC for Ground Cancel
GEB for Ground Exclusion Balance
GNC for Ground Neutralizing Circuitry
Normal for a non-Discriminating mode to find everything
All Metal which was a logical design for what the VLF mode achieved.

But with the 'advancement' of new technology came drawbacks that we, the consumers, had to deal with afield.


Quote
Hombre
I have tried the TR disc. mode on the 5900 and XL Pro but even trying it on my ground which is mild, it did not work well.
The ground I generally search here in Oregon, Utah, Nevada and other western states tends to be more mineralized and with a higher MMI than ground I have hunted in Missouri, Kansas, Oklahoma, Texas and a few of other eastern states, so I envy you and others who live and hunt in more favorable ground environments. But those good old TR and TR-Disc. model still worked well for me when I did my part of having patience and using proper operator coil control, and especially since they worked at or near 100 kHz.

Going back to the mid-to-late '70s we had 'progressed' to the VLF Ground Cancelling detectors that let us find All Metals and ignore the ground issues with coil positioning, but that meant hobbyists were also finding and digging more unwanted junk. The new detectors could 'find-it-all' and got improved detection depth, especially in more mineralized ground, and the hobbyists liked the search operation without falsing when raising and lowering the search coil, but missed having a conventional TR-Disc. mode to be able to reject unwanted trash like iron, foil, bottle caps, etc.

The design engineers were very quick to respond to this need and within about a year we had dual-mode detectors called VLF/TR-Disc. Those gave use the ability to basically discriminate the ground and search comfortably for everything, then once a target was located we would pinpoint, then move the search coil to the side and switch to the TR-Disc. mode That allowed us to check a located target in a conventional TR-Disc. mode, but also required us to go back to using more operator coil-control, and patience, because the TR-Disc mode is reactive to the ground mineral like before with coil height changes.

Actually, it was worse than those earlier TR and TR-Disc. models because the early models worked at the higher operating frequency and the new VLF/TR-Disc. models were operating in the Very Low Frequency Range and that made them much 'touchier' to subtle coil height shifts from or toward the ground. Plus many people didn't know how to use them and the differences in performance between the two modes so they were leaving a lot of good targets behind because the TR-Disc. mode didn't get the depth of the All Metal mode.

So with your White's 5900 and XL Pro models, working way down at 6.59 kHz in the VLF range, that does make them a little more challenging to use in the TR-Disc. mode than the older higher-frequency designs. It can help a unit if there is a Sensitivity control that is tied in with the TR-Disc. mode to reduce it so that it isn't quite as reactive to the ground mineral influence.


Quote
Hombre
I had to raise the Disc. too much to be of any worth here,
And there again we have a problem with the use of TR-Discrimination operation. Conventional TR's work well when it comes to handling most common iron nails. Remember that we are usually looking for desired targets that have a higher level of conductivity, and when we look at a scale of typical target conductivity, going from left to right, it would appear somewhat like this:

Ground .. Man-Made Iron .. Sm. Foil .. Lg. Foil .. 5¢ .. Tabs .. Screw Caps/Zn 1¢ .. Cu 1¢/10¢ .. 25¢ .. 50¢ .. silver $1


Ground runs from the most magnetic mineral iron up to milder, more favorable ground minerals.

Man-Made Iron includes most common iron or ferrous-based metal objects and a lot of where metals fall in the entire scale is determined by the size, shape, and alloy make-up of the metal. However, we also have to factor in how some types of detectors and/or search coil designs deal with various man-made iron trash. A prime example are those blasted pry-off bottle caps or crown caps.

Once we are out of the ferrous range and dealing with non-ferrous objects, it gets much easier to 'classify' or Discriminate them based upon ally content, size and shape.

So, what does this have to do with your posted statement? Simple.

You said you: ".. had to raise the Disc. to be of any worth here."

But, increasing the Discrimination makes use of a conventional TR-Disc. mode more difficult.

A 'conventional' TR w/o Discrimination, when tuned, will be operating at a point somewhere in the scale of Man-Made Iron where it will usually just barely be ignoring common iron nails. That means that the ground signal will have a negative influence on the TR's performance as you raise or lower the coil from or towards the ground because, is essence, a TR is rejecting the ground and some lower-end ferrous junk.

But as you increase the Discrimination level, such as up to reject Large Foil and still be just below a 5¢ coin to accept it, you have now shifted the operation level on the TR much farther from the ground mineral as well as common iron debris, and therefore the TR-Disc. mode is going to be more negatively reactive with any search coil movement from the operating height and also much more reactive to the negative influence of any ground change, more mineralized rocks, nails or other magnetic-based metals that are close enough to effect the EMF.

So use of variable Discrimination in the conventional TR mode, combined with operating in a much lower frequency by being in the VLF range, almost always results in poor performance, erratic behavior (of the detector, not to be confused with the operator bashing the blasted thing against a tree), and ample frustration (now, that one is human related).

In about '78, George Payne, then with Bounty Hunter, patented the first ground cancelling Discriminator called the Red Baron, and he coined the term SPD (for Synchronous Phase Discrimination), to describe how it worked. It also worked down in the 6.59 kHz range, and what it was doing was operating in a VLF Ground Cancelling mode, AND incorporating trash target Discrimination. But to achieve the ability to reject ground minerals and reject trash at the same time, the search coil had to be swept at a very, very brisk sweep speed. You had the comfort of ignoring the ground so the coil could be raised or lowered a little w/o falsing, and you could get rid of unwanted junk .... but it came at a price of using almost a golf-swing motion to make it work.

Back then other detector makers started making similar circuitry and they referred to that mode as VLF-Disc. and you could buy a detector with three models giving you VLF (All Metal Ground Cancelling) / VLF-Disc. (to cancel the ground signal and trash signals w/motion-based operation) / and TR-Disc. (which was just the former Disc. mode that didn't require a fast sweep).

In '82 Fisher introduced David Johnson's 1260-X which was our first popular slow-motion/quicker-response VLF-Disc. model, and in mid-'83 Tesoro introduced Jack Gifford's much improved performance Inca what was slow-motion/silent-search/quick-response and also handled nails and other iron quite well. That's a model you know well, Randy. thumbs up

Those two models also kind of signaled a trend in detector design. While some a few manufacturers hung in there a long time making 3-mode detectors that included a conventional TR-Disc., most manufacturers had abandoned that mode because at the lower frequencies and with the use of variable Discrimination, most consumers just never used it and didn't want it. The new 'trend' was to only offer All Metal and motion-based Discriminating modes like the Inca and here we are today.

We didn't need that TR-Disc. on the 5900 and XL Pro models, the last hold-outs, and we don't have it on popular models this past 35 years such as a Classic ID or IDX Pro, MX-7, CoRe, Relic, AT Pro, AT-Max, F-19, T2, F-75, Omega 8000, MXT Pro, Explorer II, CTX-3030, Equinox, Bandido II µMAX, Silver Sabre II, Anfibio, GTi 2500, GMT-1650, and other dated to modern models.


Quote
Hombre
It might work on pure white non mineral sand, but we do not have those conditions where I live.
Those very nice and proper Florida Beaches were good places to use them, but a lot of us who got started and hunted hard and often back when higher-frequency TR's were popular did quite well, and we didn't all have mellow ground. Those straight TR's worked well in iron nail infested sites, and are often unmatched by most of today's high-tech, digitally designed, fancy and multi-featured detectors.

None of them are perfect, however, and in the quick test sample I have here in my den, it was 3 old TR's using their 'standard' function and not a Discriminating mode, plus the Nokta CoRe and Relic that easily handled this particular single iron nail challenge laying on a copper button front-piece. No, I don't have all the competitor's models on hand, but I know from experience that some of them will also struggle to pass this one test.

That's why I enjoy having a well-balanced Detector Team keeping me outfitted to take on any different site challenges I might encounter or grab for special search needs I might take on like Cache Hunting.

Monte

"Your EYES ... the only 100% accurate form of Discrimination!"

Stinkwater Wells
Trading Post

Metal Detector Evaluations and Product Reviews
'How-To' help for Coin & Jewelry Hunting, Relic Hunting and Useful Techniques.

'Regular-Use Detector Team' are models from: Fisher, Nokta / Makro, Teknetics, Tesoro and White's
'Specialty-Use Detectors' are models from: Compass, Garrett and Teknetics
Pinpointers: Using Nokta / Makro and Uniprobe Pointers.
Headphones: Using Killer B's 'Hornet' and White's Pro Star and Detector Pro's Uniprobe ... All w/'tank style' ear cups.
Recovery Gear: Using White's DigMaster digging tool and Signature Series pouch.
Note: Detectors are listed alphabetically by Brand. Models are chosen as desired based on search site conditions.
Some models are assigned for 'Regular-Use' and others are on-hand for 'Specialty Use.'
Additional search coils, mounted on spare lower-rods, are on-hand in my Accessory Coil Tote.


*** All working well today to make memories for tomorrow. ***

monte@stinkwaterwells.com .. or .. monte@ahrps.org
(503) 481-8147
Subject Author Views Posted

Early morning and this OLD guy just tinkered with OLD and NEW detectors.

Monte 205 September 21, 2018 08:58AM

TR & TR-Disc. -- Tuning .. related to this initial thread post.

Monte 98 September 26, 2018 05:27AM

Next guess, Compass Coin Hustler, Garrett Master Hunter, Nokta CoRe, Nokta Relic and White's MX7...

Hombre 106 September 22, 2018 05:36PM

Randy, you are ooh so close! You got 4 out of 5.

Monte 112 September 22, 2018 06:55PM

Re: Randy, you are ooh so close! You got 4 out of 5.

NWCindy 81 September 25, 2018 02:29PM

NWCindy, you are correct regarding a chance discovery.

Monte 92 September 26, 2018 07:19AM

Do I at least get a consolation prize?.............LOL

Hombre 91 September 22, 2018 08:29PM

A consolation prize? .... Never thouht of that, but here itn is:

Monte 117 September 23, 2018 11:17AM

Re: A consolation prize? .... Never thouht of that, but here itn is:

WM6 74 September 26, 2018 01:40PM

Working on a book, and other ideas. Thanks. N/T

Monte 83 September 26, 2018 05:31PM

That was interesting.

OregonGregg 109 September 24, 2018 07:15AM

Thanks for that history lesson & nice consolation prizethumbs up

Hombre 89 September 23, 2018 02:22PM

Don't be too alarmed, but this reply is brief.eye popping smiley

Monte 99 September 23, 2018 11:57PM

Re: Thanks for that history lesson & nice consolation prizethumbs up

jmaryt 122 September 23, 2018 11:18PM

Hi jmaryt ....lets talk about the 6000 Pro XL later it was named XL Pro

Hombre 89 September 24, 2018 08:44AM

Re: Hi jmaryt ....lets talk about the 6000 Pro XL later it was named XL Pro

jmaryt 86 September 24, 2018 11:43AM

Re: Early morning and this OLD guy just tinkered with OLD and NEW detectors.

Timbertodd 112 September 22, 2018 10:30AM

Re: Early morning and this OLD guy just tinkered with OLD and NEW detectors.

Timbertodd 96 September 22, 2018 06:24PM

Nice guess, Todd, but how many were correct?

Monte 74 September 22, 2018 05:11PM

My Guess

OregonGregg 114 September 22, 2018 06:33AM

Gregg, your 'guess' was correct, but only 1 of the 5.

Monte 107 September 22, 2018 08:12AM

Re: Early morning and this OLD guy just tinkered with OLD and NEW detectors.

jmaryt 96 September 21, 2018 11:48PM

j.t., about the Mojave w/7" Concentric

Monte 114 September 22, 2018 07:54AM

Re: j.t., about the Mojave w/7" Concentric

jmaryt 87 September 22, 2018 05:28PM

My pick for the 5 winnerssmiling smiley

Hombre 114 September 21, 2018 09:38AM

Randy you had two correct out of your five guesses.

Monte 111 September 21, 2018 02:53PM

Okay, I tried these other 4 models. confused smiley

Monte 109 September 21, 2018 04:18PM



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