Bought the X-Terra 705 last week with 7.5khz 9 inch round coil. Also bought a 3khz 9 inch round coil. Did the test in my cellar test garden box, filled with 6.5 inches clay cat litter. The 7.5 kHz coil actually gave a better audio signal than the 3khz coil with a Merc dime under the box. (The clay filled box was on top of another box to keep it off the cellar floor.) The meter was jumping all over so I was relying on tones only. I kept the same settings when switching coils. Maybe I'm not doing something right but the 3khz coil didn't do any better than the 7.5 kHz.
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Coil test comparison, FWIW
- Thread starter jabbo
- Start date
Real world comparisons are the only accurate way to make such a test. What you did was essentially an air test with kitty litter in between the coin and coils, and it isn't truly representative of anything.
Undisturbed ground has developed a "matrix', which does not exist in kitty litter, or in freshly planted coin gardens. Ground moisture is another factor.
Do your test in real world conditions and the outcome will be different.
Do your test in real world conditions and the outcome will be different.
I agree with Longhair here.
If you are looking to test the difference between 7.5 and 3KHz, you must use mineralized soil. Moisture definitely makes a difference as well.
In my case, I use a 12" deep box of "Play Sand" from Lowes. It is moderately mineralized. I ran a test the other day wherein my MXT (14KHz) could barely detect a sliver dime at 5", but an old Classic III Sl (6.59KHz) had no problem at all and was smooth as silk. Oh, BTW, the sand was wet from the rain we've been having (Oregon). 2 days later, after a couple days of sunlight on the test box, the MXT was doing much better. Still not as good as the Classic, but an improvment, most likely due to the soil drying out some. For the same reason higher frequency detectors are more sensitive to smaller and less conductive metals, they are more desensitized by mineralization and salts.
I'm anxiously awaiting my 9" 3KHz concetric to compare it to the other frequencies and other detectors.
George
If you are looking to test the difference between 7.5 and 3KHz, you must use mineralized soil. Moisture definitely makes a difference as well.
In my case, I use a 12" deep box of "Play Sand" from Lowes. It is moderately mineralized. I ran a test the other day wherein my MXT (14KHz) could barely detect a sliver dime at 5", but an old Classic III Sl (6.59KHz) had no problem at all and was smooth as silk. Oh, BTW, the sand was wet from the rain we've been having (Oregon). 2 days later, after a couple days of sunlight on the test box, the MXT was doing much better. Still not as good as the Classic, but an improvment, most likely due to the soil drying out some. For the same reason higher frequency detectors are more sensitive to smaller and less conductive metals, they are more desensitized by mineralization and salts.
I'm anxiously awaiting my 9" 3KHz concetric to compare it to the other frequencies and other detectors.
George
Quote: Question is, is your litter the same as the dirt you hunt in?
I don't know if it is but the litter reduces the depth compared to air tests. The soil in my area is lightly mineralized and affects the detecting range. Tomorrow I will get some play box sand at Lowes and make a test garden about 12 inches deep. Will line the box with plastic film and moisten the sand. In air tests the 9 inch 3 kHz coil gives a good decent audio up to 8.5 inches and the 6 inch 3khz Coiltek Digger coil goes almost as deep in air.
I don't know if it is but the litter reduces the depth compared to air tests. The soil in my area is lightly mineralized and affects the detecting range. Tomorrow I will get some play box sand at Lowes and make a test garden about 12 inches deep. Will line the box with plastic film and moisten the sand. In air tests the 9 inch 3 kHz coil gives a good decent audio up to 8.5 inches and the 6 inch 3khz Coiltek Digger coil goes almost as deep in air.
Mark in S.E. IA
New member
jabbo you are wasting your time and money by using kitty litter for a test bed. Also air test are pretty much a waste of time too. MDer's were made to detect things outside in the dirt.
gabellie, your sandbox test outside would be ok if you only hunted at fresh water beaches and if the coins an rings sat in it for a good 2 years or more before you did your test. Coins need to build up a Halo effect and that takes a few years before you would get any good true tests.
gabellie, your sandbox test outside would be ok if you only hunted at fresh water beaches and if the coins an rings sat in it for a good 2 years or more before you did your test. Coins need to build up a Halo effect and that takes a few years before you would get any good true tests.
Mark in S.E. IA said:
-----------------------------------------
Mark, if you do a little research, you'll find that the "halo effect" is predominately a myth, certainly for silver and gold.
I set up a completely legitimate test condition to COMPARE detectors and coils on a deep coin. The point of the test was comparison, not absolute depth measurments.For that comparison, it is totally relevant.
For the most part, doing actual in the dirt tests, simply provide more background signal (the dirt) to reduce the dynamic range of the detector, and change the phase of a weak target.
George
Neil
Well-known member
glabelle said:
How about less research and tests and just go hunting and pay attention to your finds, measure your depths and so on? Use mother earth as your test bed, isn't that what you bought the detector for?
I don't know why so many choose to play around with test gardens and the like. Spend the same amount of time getting your fingers dirty and your gonna really know what your detector is telling you.
[Bought the X-Terra 705 last week with 7.5khz 9 inch round coil. Also bought a 3khz 9 inch round coil. Did the test in my cellar test garden box, filled with 6.5 inches clay cat litter. The 7.5 kHz coil actually gave a better audio signal than the 3khz coil with a Merc dime under the box. (The clay filled box was on top of another box to keep it off the cellar floor.) The meter was jumping all over so I was relying on tones only. I kept the same settings when switching coils. Maybe I'm not doing something right but the 3khz coil didn't do any better than the 7.5 kHz.quote=jabbo]
[/quote]
IMO, the "meter jumping all over" is likely due to interference. Each frequency of coil reacts differently to interference. And if you are using this in the house, it is hard to imagine not having interference from something. Changing NC channels might help stabilize the detector. And obtaining a proper ground balance would help as well. But that isn't possible when using the detector indoors.
All three coil frequencies will detect anything metal. The primary difference (IMO) is how the LF coils respond to high conductive targets compared to ferrous targets. The reason I like the LF coil is because it provides a distinct audio response on deeply buried iron. That is an important factor to me for the sites I hunt. HH Randy
[/quote]
IMO, the "meter jumping all over" is likely due to interference. Each frequency of coil reacts differently to interference. And if you are using this in the house, it is hard to imagine not having interference from something. Changing NC channels might help stabilize the detector. And obtaining a proper ground balance would help as well. But that isn't possible when using the detector indoors.
All three coil frequencies will detect anything metal. The primary difference (IMO) is how the LF coils respond to high conductive targets compared to ferrous targets. The reason I like the LF coil is because it provides a distinct audio response on deeply buried iron. That is an important factor to me for the sites I hunt. HH Randy
Mark in S.E. IA
New member
ok, you guys keep playing in ur lil sand boxes and I'll MD in the dirt outside and keep finding the old coins.
Mark in S.E. IA
New member
yea they are starting to plant here too.
Hey, NICE seated and IH's.
I was in the fields most of the day and all I found was 4 wheat's and a 1884 IH. At least one of the wheat's is a 24d
Hey, NICE seated and IH's.
I was in the fields most of the day and all I found was 4 wheat's and a 1884 IH. At least one of the wheat's is a 24d
Digger said:
Good to see you're getting out some. Congrats on the finds!Digger said:
They're fitting fields and planting here too. It's a race now.
This is my first MineLab, had it only a week now, and one thing I have to keep in mind, it's not one of the deeper detecting multi-frequency MineLabs. IMO, it acts like any other single frequency detector I had. At least that's the way I see it. Somebody correct me if I'm wrong.
I have an Explorer SE that I have considerable time on, and given equivalent coil size, it doesn't find anything any deeper than a properly set up Xterra.
And what we're trying to tell you, is that until you take it out in the field you can't really appreciate what it can do.
And what we're trying to tell you, is that until you take it out in the field you can't really appreciate what it can do.