EMI --- is it present??

tnsharpshooter said:

Very possible to have 2 different tx freqs that seem to be clean sounding-- yet when comparing a signal using the 2 freqs,,, one signal may be appreciably better than the other.

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One of the best uses of an air test in the field right there. One frequency on a certain day (or hour) might air test a coin an inch or two more than the other frequencies, and if you can't hear the EMI, this will let you know it's there and which frequency you should use at the time.

Great post, tnsharpshooter.

I suppose if you really want to be sure about EMI you could get an EMF detector like what the paranormal folks use. Of course the EMF detector is used by some electrical and network folks but the only time I have ever witnessed one was on Ghost Hunters.

One of the many uses for the F75 in the manual is........

to raise the coil and move it around till you find the source of the emi. But I do believe it is always present. Underground wires, cameras everywhere now, even burgler alarms on stores and banks that would set off my radar detector. I have found to eliminate what is going into the coil and let the detector do it job is best so I understand what the OP is saying. I am curious though how I can now turn my F75 all the way up and it still works.

SwingyThingy said:

to raise the coil and move it around till you find the source of the emi. But I do believe it is always present. Underground wires, cameras everywhere now, even burgler alarms on stores and banks that would set off my radar detector. I have found to eliminate what is going into the coil and let the detector do it job is best so I understand what the OP is saying. I am curious though how I can now turn my F75 all the way up and it still works.

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A lot of detectors will still work with EMI present.
But a person could for example lose .5 or even 1" of depth.
Could this loss of depth prevent making a find?? Yep

Little bit older post but because lately I've had very sketchy operation on my CTX, this issue is very relavent. One day with these settings I can do well. The next day with the same settings and the machine is out of sorts,just not able to do what it was doing the day before,regarding even the way it hits iron. I am going to be paying ALOT of attention to this EMI subject from here on out, because there ARE no other variables in play...NONE.
Varying moisture levels, attitude of operator,etc. do NOT change so dramatically from day to day that one day signals are everywhere, the next...weird,almost unstable operation and NONE of even the BAD signals are clear.
I am going to start by carrying a silver dime to air test with at a site before I even begin. Running Auto+3 some days with the exact same setup I'll get 8" coins without much trouble, the next day I can find NOTHING even close to that, and everything seems "mushy" and unclear.
I am on a QUEST to figure out how to determine the levels of localized EMI, silent or not. It is KILLING depth,accuracy and my entire detecting experience in general.

I'm sure that someone has invented a gadget with bar graphs that can show you which frequency is causing the problem at a particular site.

Cloud cover sometimes increases EMI at certain sites, because apparently it reflects the EMI back towards the ground and not out into space.

I've detected with a guy who swings a Minelab Etrac that has all those different frequencies. My F75, Teknetics T2 and other detectors wouldn't do worth a flip unless I got really far away from him. Don't let a Etrac ruin your day.

beephead

beephead said:

I'm sure that someone has invented a gadget with bar graphs that can show you which frequency is causing the problem at a particular site.

Cloud cover sometimes increases EMI at certain sites, because apparently it reflects the EMI back towards the ground and not out into space.

I've detected with a guy who swings a Minelab Etrac that has all those different frequencies. My F75, Teknetics T2 and other detectors wouldn't do worth a flip unless I got really far away from him. Don't let a Etrac ruin your day.

beephead

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This is funny to me...should be on a T Shirt.

I hunt with a friend from time to time that uses an ETrac.
Haven't noticed a whole lot of problems hunting near him with my F70.
I do ruin his day a lot though when he goes over an area and I come up behind him and find great things he missed.
I don't think that tool is incapable of finding things in our extra crazy dirt but more about the huge amount of extra work I put in to figure out the strange and skewed signals we get here on deeper targets that he just hasn't...yet.

Lots of fun rubbing great treasure in his face all day after I find them but he is a big boy and can take it.
He does the same to me once in awhile.
Must be a guy thing.