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ON THE HORIZON = MDT-8000
Posted by NASA-Tom
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Re: ON THE HORIZON = MDT-8000 November 24, 2021 04:43AM |
So, this is going to be a bit long...don't say I didn't warn you!
As some know, I bought an MDT 8000 from Dimitar a few months ago, but other than working with it some in my test garden, I haven't had time to get it out "into the field." Today was that day.
I decided to do something that was probably unwise, for a first time using the machine outside of a sanitized (no trash) test garden -- I decided to head out mid afternoon to a spot in an old city park. For background, our town (and -- this entire portion of our state) dates to 1891, the year that this portion of Oklahoma was opened to "white settlement." Our city park is on the original city plat, but not sure when it actually came "into use." I have dug two Seated coins from this park -- one an 1891 quarter in pristine condition from about 8" deep, so that likely confirms usage back into the early 1890s.
ANYWAY, this one little "hot spot," as I came to call it, centers around some type of small concrete pad, with metal embedded. I've hypothesized maybe a flagpole, or water fountain at one time, not sure. Anyway, whatever the case, we figured out (in hindsight) that whatever was here, drew a crowd...because this concrete pad proved (in hindsight) to be the centerpoint -- or bullseye -- of literally dozens of old coins. Each coin dug was in the 7" to 9" depth range, and none newer than 1908. Once we happened upon this spot, we hunted it relentlessly for weeks, until it eventually went dry. We found probably two dozen Barber dimes, at least that many Indian Heads, one to two dozen V-nickels, and a Barber quarter, plus two Seated dimes. With nothing "newer" than 1908 found, we speculate that whatever drew folks to this spot, disappeared at that time (leaving just the little concrete pad).
Once this spot began to play out (most coins were dug by my hunting buddy running an E-Trac, and me with an Explorer SE Pro), we then invited other guys to help clean the rest of it out; several other machines were used, including an F75, Gold Bug Pro, additional E-Tracs, etc. Finally, everyone gave up on the spot, but since this park is close to where I live and is my "go-to" park when I have nowhere better (or not much time), I still spend at least an hour or so in the hot spot each time I hunt this park, "just in case." Five or six years ago, I got a lone Barber dime with my Explorer, at about 8" deep. After I got my CTX, I then ran it through this spot thoroughly, but all I was able to uncover was a single wheat cent on the "fringe" of the hot spot (which was odd, as it was the "newest" coin found in this area; a slightly older Merc dime was also found with my Explorer on the fringe of the area, 7 or 8 years ago). Anyway, that wheat cent was the only additional coin I was ever able to locate in this spot, with the CTX -- and I worked HARD at it! That was about 4 years ago, and I haven't dug another coin from the hot spot since. Still -- I have always felt strongly that there HAVE to be additional, old coins in this spot, just a bit beyond the maximum depth that even the deepest machines can reach (about 9" in our dirt, on a dime). That's why I spent so much time there with the CTX, trying to find just one more silver coin (to no avail).
SO -- that brings me back around to today, and the MDT 8000. Again, it is obviously not the smartest plan, on the very first outing with a new machine, to take it to a spot with lots of old, deep nails, and with any coins left likely to be at a minimum 8" depth or beyond, and then to crank the machine up nearly as hot as it can go, hoping to achieve the necessary depth. BUT -- that's what I did. I set the machine up at 6.4kHz, DISC mode, zero discrimination, threshold -1, sensitivity 8, and then I set up salt balance and ground balance as NASA-Tom has been doing, to limit the machine's sensitivity to small rusty iron, and foil (Salt Balance 48, Ground Balance 750). Well, first of all, the machine set up this way was absolutely quiet, EMI-wise. I probably could have gone to 0 on the threshold, and 9 on the sensitivity, but decided to hold back at least a little!
I must admit, after the first hour, I wanted to wrap it around a tree. SO much noise (ground, not EMI), and I had no clue what the machine was telling me. I was getting tons of iron low tones, that would mix with high tones (and some with some mid tones mixed in), but these were all iron/nails (the Tarsacci seems to like to high-tone on very small, very thin/fine nails). Meanwhile, I was getting TONS of high-tone chirps, and because I knew any coin would be deep and subtle, I was trying to decipher each of the high-tone chirps I was hearing, and thus it was slow going, trying to investigate every one of those. Finally, I couldn't take it anymore, and decided those high tones may have something to do with ground balance, so instead of my pre-set at 750, I ground balanced to actual conditions (and then several times thereafter; ground balance ranged from 665 to 714 during the hunt, as the clay is not as red in this park, as most other portions of my area). When properly balanced, this cut down substantially on the high-tone chirps, and kept them all as low-tone chirps (so I wonder now if it was tiny iron/rust flecks, that were "wrapping around" at times into the upper 20s and thus high-toning, due to ground balance being slightly too high, at 750?)
After this, it got a little better, but I dug all manner of iron (especially very small thin wiry pieces), but also screws, bolts, etc., plus some non-ferrous junk (a bullet, aluminum (can slaw), tabs, and other bits of various metals). BUT -- just about the time I was wondering if I was ever going to start understanding the machine's language, I got another soft high tone. This one was repeatable essentially all the way around as I rotated around the target, without quite as much low-toning iron mixed in. Not ENTIRELY different from a number of other, small nails that I had dug, but I felt a bit more confident that it was non-ferrous (IDs generally low 20s). Imagine my shock, when -- after popping out a deep plug, there at the very bottom of the hole was the glint of silver! A 1903 Barber dime! I could NOT believe it. I cannot tell you the countless number of times this exact spot was swung over with other units; it was a mere 10 feet from that concrete pad, that marked the centroid of all of the coins we have found here (and therefore the portion of the area that received the greatest number of "coil swings"). I am not positive on depth, as it was in the deepest part of the hole, so it clearly was right at the base of the plug and may have slid to the deepest part when I removed the plug, but it was every bit of 9" -- well beyond the length of my Garrett Carrot. (OH -- and there was a small nail 3" deep, and about 3" from where the dime was located -- responsible for some of the low tones that I was hearing).
This dig allowed me to learn a few things, and confirmed that A -- there ARE INDEED additional coins in this spot that were just out of reach of all of the other machines, and B -- that the Tarsacci is capable of exceeding the maximum depth range of all other Flagship machines that have been run through this spot countless times.
So, I continued onward for a bit longer, digging a bunch of can slaw that bounced between mid and high tone, a few ring tabs, etc. It was getting dark by this point, but I wanted to run through the portion of the hot spot where the two Seated dimes were found, for just a few minutes, before calling it a day. A few more non-ferrous trash digs, and then I hit a target that had some mid and low tones mixed in -- similar to so many other targets today -- but I could get a pretty consistent low 20s from several directions, similar to the Barber dime from earlier. I dug a deep plug, and there in the very bottom of the plug (roughly 8" deep) was yet another Barber dime!
I know, I know, two Barber dimes is not the world's most amazing hunt. BUT -- because I know how many hours and hours and hours were spent criss-crossing this hot spot, with multiple top-performing machines, by multiple, experienced hunters, and because I know how long it has been since a single silver coin was dug from this spot, AND given that calling me "green" on the MDT 8000 is an understatement, I have to say that I am MORE than impressed. It has been ten years since my last two-silver day from this spot, and I estimate 5 years since the last time I dug a single one. THIS, to me, is really, really amazing, and speaks to why NASA-Tom refers to this machine as having "world flagship" status.
My early take is that NO -- it is not an everyday coin hunter in a park full of trash. I feel that the ID is not accurate ENOUGH to allow you to cherry-pick, but it IS accurate enough to get you "in the ballpark." I don't like the tones; to my ears, the mid tone is the most attention-getting, and the high tone is a bit "muted." BUT -- I began to sense some intelligence in the tones; a rapid pre-amble and post-amble seems to exist with "better" targets. If you are getting some mid and high tones mixed in with lots of iron tones, but you just can't quite get the non-ferrous tones to "settle into one specific spot," these seemed to prove to be falses off the nails. I dug one square nail that gave a really nice, consistent high-tone false about 3" or 4" from the head of the nail. There is some modulation in the tones with depth; it will take some getting used to, but you can learn rather quickly to begin to tell a deeper (or smaller) target versus a shallow one. IF it's not too trashy, pinpoint helps there, also, as pinpoint audio is well modulated; volume (and signal strength) are quite diminished when pinpointing deep (or small) targets. Ground balance -- at least for a newbie who doesn't want to deal with a bunch of ground noise -- is IMPORTANT; it has to be "spot on" for the machine to behave "properly," from my view. So, obviously, LOTS of learning to do, but what a great start. To say that I am "impressed" would be an understatement...
Steve
Edited 2 time(s). Last edit at 11/24/2021 04:51AM by steveg.
As some know, I bought an MDT 8000 from Dimitar a few months ago, but other than working with it some in my test garden, I haven't had time to get it out "into the field." Today was that day.
I decided to do something that was probably unwise, for a first time using the machine outside of a sanitized (no trash) test garden -- I decided to head out mid afternoon to a spot in an old city park. For background, our town (and -- this entire portion of our state) dates to 1891, the year that this portion of Oklahoma was opened to "white settlement." Our city park is on the original city plat, but not sure when it actually came "into use." I have dug two Seated coins from this park -- one an 1891 quarter in pristine condition from about 8" deep, so that likely confirms usage back into the early 1890s.
ANYWAY, this one little "hot spot," as I came to call it, centers around some type of small concrete pad, with metal embedded. I've hypothesized maybe a flagpole, or water fountain at one time, not sure. Anyway, whatever the case, we figured out (in hindsight) that whatever was here, drew a crowd...because this concrete pad proved (in hindsight) to be the centerpoint -- or bullseye -- of literally dozens of old coins. Each coin dug was in the 7" to 9" depth range, and none newer than 1908. Once we happened upon this spot, we hunted it relentlessly for weeks, until it eventually went dry. We found probably two dozen Barber dimes, at least that many Indian Heads, one to two dozen V-nickels, and a Barber quarter, plus two Seated dimes. With nothing "newer" than 1908 found, we speculate that whatever drew folks to this spot, disappeared at that time (leaving just the little concrete pad).
Once this spot began to play out (most coins were dug by my hunting buddy running an E-Trac, and me with an Explorer SE Pro), we then invited other guys to help clean the rest of it out; several other machines were used, including an F75, Gold Bug Pro, additional E-Tracs, etc. Finally, everyone gave up on the spot, but since this park is close to where I live and is my "go-to" park when I have nowhere better (or not much time), I still spend at least an hour or so in the hot spot each time I hunt this park, "just in case." Five or six years ago, I got a lone Barber dime with my Explorer, at about 8" deep. After I got my CTX, I then ran it through this spot thoroughly, but all I was able to uncover was a single wheat cent on the "fringe" of the hot spot (which was odd, as it was the "newest" coin found in this area; a slightly older Merc dime was also found with my Explorer on the fringe of the area, 7 or 8 years ago). Anyway, that wheat cent was the only additional coin I was ever able to locate in this spot, with the CTX -- and I worked HARD at it! That was about 4 years ago, and I haven't dug another coin from the hot spot since. Still -- I have always felt strongly that there HAVE to be additional, old coins in this spot, just a bit beyond the maximum depth that even the deepest machines can reach (about 9" in our dirt, on a dime). That's why I spent so much time there with the CTX, trying to find just one more silver coin (to no avail).
SO -- that brings me back around to today, and the MDT 8000. Again, it is obviously not the smartest plan, on the very first outing with a new machine, to take it to a spot with lots of old, deep nails, and with any coins left likely to be at a minimum 8" depth or beyond, and then to crank the machine up nearly as hot as it can go, hoping to achieve the necessary depth. BUT -- that's what I did. I set the machine up at 6.4kHz, DISC mode, zero discrimination, threshold -1, sensitivity 8, and then I set up salt balance and ground balance as NASA-Tom has been doing, to limit the machine's sensitivity to small rusty iron, and foil (Salt Balance 48, Ground Balance 750). Well, first of all, the machine set up this way was absolutely quiet, EMI-wise. I probably could have gone to 0 on the threshold, and 9 on the sensitivity, but decided to hold back at least a little!
I must admit, after the first hour, I wanted to wrap it around a tree. SO much noise (ground, not EMI), and I had no clue what the machine was telling me. I was getting tons of iron low tones, that would mix with high tones (and some with some mid tones mixed in), but these were all iron/nails (the Tarsacci seems to like to high-tone on very small, very thin/fine nails). Meanwhile, I was getting TONS of high-tone chirps, and because I knew any coin would be deep and subtle, I was trying to decipher each of the high-tone chirps I was hearing, and thus it was slow going, trying to investigate every one of those. Finally, I couldn't take it anymore, and decided those high tones may have something to do with ground balance, so instead of my pre-set at 750, I ground balanced to actual conditions (and then several times thereafter; ground balance ranged from 665 to 714 during the hunt, as the clay is not as red in this park, as most other portions of my area). When properly balanced, this cut down substantially on the high-tone chirps, and kept them all as low-tone chirps (so I wonder now if it was tiny iron/rust flecks, that were "wrapping around" at times into the upper 20s and thus high-toning, due to ground balance being slightly too high, at 750?)
After this, it got a little better, but I dug all manner of iron (especially very small thin wiry pieces), but also screws, bolts, etc., plus some non-ferrous junk (a bullet, aluminum (can slaw), tabs, and other bits of various metals). BUT -- just about the time I was wondering if I was ever going to start understanding the machine's language, I got another soft high tone. This one was repeatable essentially all the way around as I rotated around the target, without quite as much low-toning iron mixed in. Not ENTIRELY different from a number of other, small nails that I had dug, but I felt a bit more confident that it was non-ferrous (IDs generally low 20s). Imagine my shock, when -- after popping out a deep plug, there at the very bottom of the hole was the glint of silver! A 1903 Barber dime! I could NOT believe it. I cannot tell you the countless number of times this exact spot was swung over with other units; it was a mere 10 feet from that concrete pad, that marked the centroid of all of the coins we have found here (and therefore the portion of the area that received the greatest number of "coil swings"). I am not positive on depth, as it was in the deepest part of the hole, so it clearly was right at the base of the plug and may have slid to the deepest part when I removed the plug, but it was every bit of 9" -- well beyond the length of my Garrett Carrot. (OH -- and there was a small nail 3" deep, and about 3" from where the dime was located -- responsible for some of the low tones that I was hearing).
This dig allowed me to learn a few things, and confirmed that A -- there ARE INDEED additional coins in this spot that were just out of reach of all of the other machines, and B -- that the Tarsacci is capable of exceeding the maximum depth range of all other Flagship machines that have been run through this spot countless times.
So, I continued onward for a bit longer, digging a bunch of can slaw that bounced between mid and high tone, a few ring tabs, etc. It was getting dark by this point, but I wanted to run through the portion of the hot spot where the two Seated dimes were found, for just a few minutes, before calling it a day. A few more non-ferrous trash digs, and then I hit a target that had some mid and low tones mixed in -- similar to so many other targets today -- but I could get a pretty consistent low 20s from several directions, similar to the Barber dime from earlier. I dug a deep plug, and there in the very bottom of the plug (roughly 8" deep) was yet another Barber dime!
I know, I know, two Barber dimes is not the world's most amazing hunt. BUT -- because I know how many hours and hours and hours were spent criss-crossing this hot spot, with multiple top-performing machines, by multiple, experienced hunters, and because I know how long it has been since a single silver coin was dug from this spot, AND given that calling me "green" on the MDT 8000 is an understatement, I have to say that I am MORE than impressed. It has been ten years since my last two-silver day from this spot, and I estimate 5 years since the last time I dug a single one. THIS, to me, is really, really amazing, and speaks to why NASA-Tom refers to this machine as having "world flagship" status.
My early take is that NO -- it is not an everyday coin hunter in a park full of trash. I feel that the ID is not accurate ENOUGH to allow you to cherry-pick, but it IS accurate enough to get you "in the ballpark." I don't like the tones; to my ears, the mid tone is the most attention-getting, and the high tone is a bit "muted." BUT -- I began to sense some intelligence in the tones; a rapid pre-amble and post-amble seems to exist with "better" targets. If you are getting some mid and high tones mixed in with lots of iron tones, but you just can't quite get the non-ferrous tones to "settle into one specific spot," these seemed to prove to be falses off the nails. I dug one square nail that gave a really nice, consistent high-tone false about 3" or 4" from the head of the nail. There is some modulation in the tones with depth; it will take some getting used to, but you can learn rather quickly to begin to tell a deeper (or smaller) target versus a shallow one. IF it's not too trashy, pinpoint helps there, also, as pinpoint audio is well modulated; volume (and signal strength) are quite diminished when pinpointing deep (or small) targets. Ground balance -- at least for a newbie who doesn't want to deal with a bunch of ground noise -- is IMPORTANT; it has to be "spot on" for the machine to behave "properly," from my view. So, obviously, LOTS of learning to do, but what a great start. To say that I am "impressed" would be an understatement...
Steve
Edited 2 time(s). Last edit at 11/24/2021 04:51AM by steveg.
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Re: ON THE HORIZON = MDT-8000 December 11, 2021 01:19AM |
OK, so I headed out again today, for a very short hunt, with the MDT 8000. I took it to the same spot I worked the last time I was out testing the Tarsacci (the little "hot spot" we found about a decade ago, and have cleaned it entirely of all "detectable" coins).
And wouldn't you know it, that once again, I managed another coin that was just beyond the depth capability of prior units; this one was roughly 9 1/4" deep, and was only 15 feet from the "center" of the hot spot (that small concrete pad I described in the prior post). I only dug about 5 or 6 targets during the hunt, and the coin (a toasted, "no-date" Indian Head Penny) was the first target dug...
It's ugly, but I consider it "victory," as -- again -- any coin dug from this spot is a coin that was "invisible" to all the other machines we hunted this small section of park with, over the years...
Also, I learned a number of things today. The last (first) time I had the Tarsacci in this spot, there was essentially ZERO EMI. Today, after the first few minutes, EMI became AWFUL. The only thing I could attribute it to, was that there were some workers nearby who were putting up Christmas lights in the park. They had hundreds of feet of lights strung out, ready to be hung, and perhaps those lights were somehow the culprit. WHATEVER THE CASE, the machine was essentially unusable. I tried lowering sensitivity, didn't help -- it just made the EMI "quieter," but it was quite audible. I tried lowering threshold, but to get the machine quiet I had to run threshold so far down, that there was no use even trying to hunt fringe-depth coins. I tried black sand on, and it mitigated EMI a bit, for a little while. But ultimately, it was just impossible to "hunt deep" with all the chatter going on. I was just about to pack it up, but thought of one other thing -- I decided to try other frequencies (I was running 6.4 kHz). I tried 9, just as bad. I tried 12, and while a BIT better, it was still unhuntable. Finally, after switching to 18 -- SILENCE! I was able to run threshold back up to 0, and sensitivity up to 8, and there was essentially no audible EMI.
SO -- I decided to hunt a bit longer, in 18 kHz. And let me tell you, that machine is a totally different unit, running 18 kHz vs. 6.4 kHz. After running at 18, going back over the same areas I had been hunting with 6.4, I found out that getting a repeatable mid tone is a relatively "rare" event, when running 6.4. Suddenly, in 18 kHz, there were mid tones -- good, repeatable mid tones -- EVERYWHERE. I dug a few; one was a deep .22 projectile. Several others were VERY small pieces of random metal. One was a deep, short piece of twisted copper wire. It liked SMALL targets, and it produces alot of solid mid-tone IDs, when running 18 kHz. But that wasn't entirely surprising. What WAS surprising was just the totally different behavior of the unit. It is a MUCH more "stable" unit running hot, in 18 kHz, vs. 6.4. The nail falsing is WAY calmed down; the staccato high tones are essentially eliminated; it seemed MUCH less sensitive as far as requiring spot-on ground balance. As a result of all of this, I very quickly gained confidence in what I was hearing -- i.e. what and where the targets were that the machine was reporting. It's hard to describe, but all I can say is the machine much more effectively conveyed "intelligence" to me in 18 kHz. I "clicked" with it much more readily, and understood much better what it was saying. Again, this was sweeping over the exact same ground I had just hunted in 6.4. Very, very interesting. I really wanted to bump it down to 12, as I knew if I could run it at a lower frequency, it should be more "resonant" with the deep high conductors, but trying to do so reminded me quickly that on this day, the only "usable" frequency was 18 kHz. I am just really amazed at what a different machine it was, and how much more "familiar" or "understandable" it felt, as compared to running it at 6.4 kHz. Just a TOTALLY different machine. Fascinating...
Steve
And wouldn't you know it, that once again, I managed another coin that was just beyond the depth capability of prior units; this one was roughly 9 1/4" deep, and was only 15 feet from the "center" of the hot spot (that small concrete pad I described in the prior post). I only dug about 5 or 6 targets during the hunt, and the coin (a toasted, "no-date" Indian Head Penny) was the first target dug...
It's ugly, but I consider it "victory," as -- again -- any coin dug from this spot is a coin that was "invisible" to all the other machines we hunted this small section of park with, over the years...
Also, I learned a number of things today. The last (first) time I had the Tarsacci in this spot, there was essentially ZERO EMI. Today, after the first few minutes, EMI became AWFUL. The only thing I could attribute it to, was that there were some workers nearby who were putting up Christmas lights in the park. They had hundreds of feet of lights strung out, ready to be hung, and perhaps those lights were somehow the culprit. WHATEVER THE CASE, the machine was essentially unusable. I tried lowering sensitivity, didn't help -- it just made the EMI "quieter," but it was quite audible. I tried lowering threshold, but to get the machine quiet I had to run threshold so far down, that there was no use even trying to hunt fringe-depth coins. I tried black sand on, and it mitigated EMI a bit, for a little while. But ultimately, it was just impossible to "hunt deep" with all the chatter going on. I was just about to pack it up, but thought of one other thing -- I decided to try other frequencies (I was running 6.4 kHz). I tried 9, just as bad. I tried 12, and while a BIT better, it was still unhuntable. Finally, after switching to 18 -- SILENCE! I was able to run threshold back up to 0, and sensitivity up to 8, and there was essentially no audible EMI.
SO -- I decided to hunt a bit longer, in 18 kHz. And let me tell you, that machine is a totally different unit, running 18 kHz vs. 6.4 kHz. After running at 18, going back over the same areas I had been hunting with 6.4, I found out that getting a repeatable mid tone is a relatively "rare" event, when running 6.4. Suddenly, in 18 kHz, there were mid tones -- good, repeatable mid tones -- EVERYWHERE. I dug a few; one was a deep .22 projectile. Several others were VERY small pieces of random metal. One was a deep, short piece of twisted copper wire. It liked SMALL targets, and it produces alot of solid mid-tone IDs, when running 18 kHz. But that wasn't entirely surprising. What WAS surprising was just the totally different behavior of the unit. It is a MUCH more "stable" unit running hot, in 18 kHz, vs. 6.4. The nail falsing is WAY calmed down; the staccato high tones are essentially eliminated; it seemed MUCH less sensitive as far as requiring spot-on ground balance. As a result of all of this, I very quickly gained confidence in what I was hearing -- i.e. what and where the targets were that the machine was reporting. It's hard to describe, but all I can say is the machine much more effectively conveyed "intelligence" to me in 18 kHz. I "clicked" with it much more readily, and understood much better what it was saying. Again, this was sweeping over the exact same ground I had just hunted in 6.4. Very, very interesting. I really wanted to bump it down to 12, as I knew if I could run it at a lower frequency, it should be more "resonant" with the deep high conductors, but trying to do so reminded me quickly that on this day, the only "usable" frequency was 18 kHz. I am just really amazed at what a different machine it was, and how much more "familiar" or "understandable" it felt, as compared to running it at 6.4 kHz. Just a TOTALLY different machine. Fascinating...
Steve
