Countering EMI in Pi detectors?

[Alluvium]

 Alluvium and all

 I have read the above posts about running the GPX in
normal timings. We only have two tiny areas on our claims
that a GPX will even function in normal timing with any coil.
 
These two areas are only a few feet by a few feet. Any other
area the GPX machines false and squeal so bad that they are
totally useless in normal timing. Every other place it is enhance
or nothing.

 Our 2200d was much better on hot ground than any of our
4000,or 4500 machines in normal timing. In the two mild areas
the 4000,and 4500's would run great and punch deep in normal.
 With the original 4500 before the recall ,an ounce plus nugget
at 3 feet in the mild ground ,was possible,and did happen. That
is why I alluded to the original pre recall 4500's in another post.

 Enhanced or smooth timings is the only thing that the GPX ML's
have going for them in hot ground. Like you said those settings
are limited to shallow gold. Once in a great while they will hit a
deeper nugget if everything is just right.

 If you are able to detect your so called hot ground in normal
timings,then you can see why I refuse to put stock in the tested
in Oz theory. We have lots of ground that the GPX series can't
handle in normal. By the way a TDI does not have any EMI or hot
ground problems,on the same ground.

Hi Sawmill,

With the problems you have running the GPX on your claims, have you tested the soil content to see if it is a salt problem.
If it is not this, it could well be a magnetic situation creating the problems with M/Lab GPX models.


The 2 small areas where you can detect using Normal timing might be the key to the trouble detecting on the rest of your claims.
Why not sample both types of ground and have them analysed this would give some insight to what you have to deal with.
If you can send me the info on the type of soil you have, I will try to work out some way to help you.

I can understand your comments about your old SD 2200D, yes they did perform a lot better, but with a DD coil mind you.
As you know as M/Lab progressed from there, with more and more sensitivity with each model.
Somewhere along the way they went too far, these later models are really made to excel at finding small tiny gold in red hot ground.

We noticed on the release of the GPX 4000 it didn't have the same depth as the GP3000 / 3500’s in Normal timing.
Things have not improved greatly from there.

With your comment about finding a 1 oz nugget at 3’feet deep

Your Quote: In the two mild areas the 4000, and 4500's would run great and punch deep in normal.
 With the original 4500 before the recall, an ounce plus nugget at 3 feet in the mild ground, was possible, and did happen.

I take you at your word on this sawmill, the ground in the USA must differ significantly from ours here.
You say you were using Normal timing in Low mineralization, so it may be possible as you say??

Well mate, I have never seen this happen, nor my mates have either, and they are professional gold miners.
Here in Australia, most gold field grounds have layers of HOT silty sedimentary clays, these come into the equation in a big way.
To find a small 1 oz nugget at this extreme depth with what we have available today here, is unheard of.

Sure you get the detecting newbies over here that say they did, or can, but we know different.
To replicate this feat here in OZ, you would have to hammer the 1oz piece into a disc of say 6” to 8”inches across.
Sit it flat at 3’ft in a bank, and use Normal timing with high settings.

Yes I agree, the smooth timings are the biggest advantage with the GPX’s, the second is all the adjustment at hand.
But you may need a Uni degree to work out what settings are best.
Smooth timings are quite choosy when detecting for deep bigger gold.

Your other Quote:   If you are able to detect your so called hot ground in normal timings, then you can see why I refuse to put stock in the tested in Oz theory. We have lots of ground that the GPX series can't handle in normal.

As I said at the start of this post, some testing of your particular soils there is required, it is no good us guessing from over here.
All I can quote is what I and my friends observe and note over here in OZ.

Without giving too much away, just remember the saying, “Coils ain’t always Coils”

Your Quote:   By the way a TDI does not have any EMI or hot ground problems, on the same ground.

I don't doubt that, as I have seen the TDI over here, Eric is the MAN.

Cheers and regards, Alluvium.

[Doug]

 Alluvium and all

 I have read the above posts about running the GPX in
normal timings. We only have two tiny areas on our claims
that a GPX will even function in normal timing with any coil.
 
These two areas are only a few feet by a few feet. Any other
area the GPX machines false and squeal so bad that they are
totally useless in normal timing. Every other place it is enhance
or nothing.

 Our 2200d was much better on hot ground than any of our
4000,or 4500 machines in normal timing. In the two mild areas
the 4000,and 4500's would run great and punch deep in normal.
 With the original 4500 before the recall ,an ounce plus nugget
at 3 feet in the mild ground ,was possible,and did happen. That
is why I alluded to the original pre recall 4500's in another post.

 Enhanced or smooth timings is the only thing that the GPX ML's
have going for them in hot ground. Like you said those settings
are limited to shallow gold. Once in a great while they will hit a
deeper nugget if everything is just right.

 If you are able to detect your so called hot ground in normal
timings,then you can see why I refuse to put stock in the tested
in Oz theory. We have lots of ground that the GPX series can't
handle in normal. By the way a TDI does not have any EMI or hot
ground problems,on the same ground.

I speculate that the reason that ML's can't cope with your ground is due to the above average concentrations and variable amounts of magnetite The ML method used to cancel the static fields from this magnetite fails when when the field strength is very substantially above above the average geomagnetic field  and varies from place to place dramatically.This I believe is because ML use a pulse train of short and long pulses to achieve GB and don't have enough time to take  a very  late sample (to cancel the induced  voltage from a coil moving through a static field)when the ground signal  induced by the pulse has completely decayed.
ML therefore have to resort in my opinion to complicated algorithmic methods which in your ground fail abysmally. The TDI uses a single pulse length and  hence can take a very late sample to properly cancel the static field (just like the QED).The TDI also probably has less overall circuit gain than a ML and this probably helps as well. In support of my speculations I have been told  that you cannot detect near large banded (magnetite) ironstone outcrops in WA and ground  covered with a lot of banded ironstone causes problems to ML's!ML must just wish that sawmills ground and banded ironstones would just disappear!
doug

[sawmill]

 Alluvium

 I sold all of our ML machines. The ground has been tested
by Allan,and Eric Foster.

 The area the 3 foot deep nugget came from is in a wash.
There is a thin layer of sand on top,and it is powdered caliche
down to a false bottom of packed clay. The caliche is dead quiet
and mild. The nugget was about 2 inches long and solid. It was
imbedded in the hard pack clay and had to be chiseled out.

 Two small areas are like this,all the rest of the ground is very hot,
and contains massive amounts of iron.

 Yes I agree Eric is one smart cookie! I thank him every time I turn
the TDI on.

[Doug]

 Alluvium and all

 I have read the above posts about running the GPX in
normal timings. We only have two tiny areas on our claims
that a GPX will even function in normal timing with any coil.
 
These two areas are only a few feet by a few feet. Any other
area the GPX machines false and squeal so bad that they are
totally useless in normal timing. Every other place it is enhance
or nothing.

 Our 2200d was much better on hot ground than any of our
4000,or 4500 machines in normal timing. In the two mild areas
the 4000,and 4500's would run great and punch deep in normal.
 With the original 4500 before the recall ,an ounce plus nugget
at 3 feet in the mild ground ,was possible,and did happen. That
is why I alluded to the original pre recall 4500's in another post.

 Enhanced or smooth timings is the only thing that the GPX ML's
have going for them in hot ground. Like you said those settings
are limited to shallow gold. Once in a great while they will hit a
deeper nugget if everything is just right.

 If you are able to detect your so called hot ground in normal
timings,then you can see why I refuse to put stock in the tested
in Oz theory. We have lots of ground that the GPX series can't
handle in normal. By the way a TDI does not have any EMI or hot
ground problems,on the same ground.

Hi Sawmill,

With the problems you have running the GPX on your claims, have you tested the soil content to see if it is a salt problem.
If it is not this, it could well be a magnetic situation creating the problems with M/Lab GPX models.


The 2 small areas where you can detect using Normal timing might be the key to the trouble detecting on the rest of your claims.
Why not sample both types of ground and have them analysed this would give some insight to what you have to deal with.
If you can send me the info on the type of soil you have, I will try to work out some way to help you.

I can understand your comments about your old SD 2200D, yes they did perform a lot better, but with a DD coil mind you.
As you know as M/Lab progressed from there, with more and more sensitivity with each model.
Somewhere along the way they went too far, these later models are really made to excel at finding small tiny gold in red hot ground.

We noticed on the release of the GPX 4000 it didn't have the same depth as the GP3000 / 3500’s in Normal timing.
Things have not improved greatly from there.

With your comment about finding a 1 oz nugget at 3’feet deep

Your Quote: In the two mild areas the 4000, and 4500's would run great and punch deep in normal.
 With the original 4500 before the recall, an ounce plus nugget at 3 feet in the mild ground, was possible, and did happen.

I take you at your word on this sawmill, the ground in the USA must differ significantly from ours here.
You say you were using Normal timing in Low mineralization, so it may be possible as you say??

Well mate, I have never seen this happen, nor my mates have either, and they are professional gold miners.
Here in Australia, most gold field grounds have layers of HOT silty sedimentary clays, these come into the equation in a big way.
To find a small 1 oz nugget at this extreme depth with what we have available today here, is unheard of.

Sure you get the detecting newbies over here that say they did, or can, but we know different.
To replicate this feat here in OZ, you would have to hammer the 1oz piece into a disc of say 6” to 8”inches across.
Sit it flat at 3’ft in a bank, and use Normal timing with high settings.

Yes I agree, the smooth timings are the biggest advantage with the GPX’s, the second is all the adjustment at hand.
But you may need a Uni degree to work out what settings are best.
Smooth timings are quite choosy when detecting for deep bigger gold.

Your other Quote:   If you are able to detect your so called hot ground in normal timings, then you can see why I refuse to put stock in the tested in Oz theory. We have lots of ground that the GPX series can't handle in normal.

As I said at the start of this post, some testing of your particular soils there is required, it is no good us guessing from over here.
All I can quote is what I and my friends observe and note over here in OZ.

Without giving too much away, just remember the saying, “Coils ain’t always Coils”

Your Quote:   By the way a TDI does not have any EMI or hot ground problems, on the same ground.

I don't doubt that, as I have seen the TDI over here, Eric is the MAN.

Cheers and regards, Alluvium.

I would like to see someone put up a video to show a 4500 detecting a solid 1 ounce nugget at 3 feet with an 18" mono in a simple air test let alone mild ground!
Until I see such a video I refuse to believe that any ML can detect a solid 1oz nugget at 3 feet!
A 1oz nugget a 3 feet goes against all the years of testing (air and in ground!) done here with every ML! It also goes against all the laws of EM and the limitations imposed on detector makers by the laws regulating the  level of transmitted EMI!
Yes I have been told of a gp (from memory)detecting a nugget at 3 feet with 11"coil,but the nugget i think was over 100oz!!!!!
doug

[sawmill]

 Doug

 In all your years of testing every ML detector, did you test
one of the first 1200 4500's, before it was sent back for the
recall repair?

[Doug]

 Doug

 In all your years of testing every ML detector, did you test
one of the first 1200 4500's, before it was sent back for the
recall repair?

I personally don't know the serial numbers of the 4500's that were tested.
doug

[NickF]

 Doug

 In all your years of testing every ML detector, did you test
one of the first 1200 4500's, before it was sent back for the
recall repair?

Hehe, some people on the forums were suspecting Minelab are holding back on technology, so they can make incremental upgrades to the equipment they sell. Probably back then, ML thought ...oops, this version is far too advanced, let's make it dumber. So they did the recall :)
I am just joking.

Regards,
Nicolae