Silent EMI The Quiet Killer

Hi,,,,Okay I'm not feeling very loquacious, so I will keep try to keep it brief and straight to the point..... Year::2013.... Location::park near a big factory....Problem::coin finds were sparse until after 5:00 pm....Read on where I confirm the problem and also came up with an easy solution..LoL..My machine would sound normal and seemed to work like it normally does with no added noise etc. prior to 5:00 pm...But it was hard to find a coin, even the normal trash & ground noise seemed somewhat quieter than it normally is or should of been....After trying other machines and repeating this process on consecutive days....A light finally turned on, it was kinda dim at first....So I decided to do an air test before and after 5:00 pm, because the factory shuts down at 5:00 pm....Sure enough whatever they have running there causes a considerable loss of depth....Solution wait until after 5:00 pm..LoL..I have another spot that I can only work on Sundays....This EMI is just the opposite it's not silent, it's so noisy that it's totally impossible to use your machine any other day but Sunday....I guess all I can say is welcome to the crazy secret world of EMI....Another added note::some cell phones can cause adverse effects too....Can anyone else confirm a strange Phenomenon like this happening to you?....JJ

An interesting observation and I would not be surprised at your findings. All the more to consider when out.

Certainly. And I commented on this exact subject in the "Rcpt Ack of F75 LTD Proto" thread. It is more common than you may suspect.
The one fortunate thing about the F75 platform is......... silent EMI is nearly impossible/improbable with this platform,,, as it will very easily audibly let you know about EMI status/conditions.

Something to think about when hunting with a buddy...does his unit silently cause loss of depth or efficiency???
I know one thing hunt with two CZ's even at a distance and you don't hear it but they are talking to each other and cause depth loss...
So much that ...well just won't hunt with a CZ guy kind of thing...been there done that....

Hi Dan,,,you know it's funny you mentioned the buddy thing and possible depth loss....This is very possible....I know a T2 and an AT don't play together well in the same sandbox.....JJ

2 Deus's don't play well together either -

you have to frequency shift just to "try" and get them to ignore each other and that doesn't always work the greatest -- if you're too close to each other forget it -- you have to spread out/away from each other

Did notice this years ago with two Tesoro Cibolas I had, you heard each other when close. At about 12 feet away everything seemed rosey, no apparent audible interference. Found by doing an air test at that time, depth loss was about 50%.

Funny thing long ago if hunting a new spot and I wasn't finding anything, I would then do an air test or a in ground test just to see if the detector had a problem. So I would reground balance in hopes it was just a mineralization problem. Sometimes would just chaulk it up to bad, hot ground. Come back another time with a different detector that would work there. So now wondering back then if it may not have been the ground but silent EMI. Some machines could handle it better than others..........? That was a time when cellphones were still housed in a big box the size of a small suitcase or lunchbox.

Sometimes think all the EMI zipping thru my head makes me tired and finally gives me a headache. The world was much quieter at one time.

DeepTech Vista X with 3 search coils.
Works for me

Hi MRH,, yeah if you are getting crosstalk chatter/noise, then you can be rest assured that there is some silent EMI or a lack of depth taking place at some point....When I do not hear foil or regular ground noise is not as prevalent, I know something is not right....At that point it's left up to the silent hidden EMI gods....JJ

That's why I use an FBS
Minelab. It destroys your signal but doesn't effect mine. LOL

ShovelNose Wrote:
-------------------------------------------------------
> That's why I use an FBS
> Minelab. It destroys your signal but doesn't
> effect mine. LOL

That may be the case when hunting with someone too closely (machine to machine so to speak) but FBS machines are vulnerable to EMI just the same as all others

in fact

my E-Trac was way worse at handling it than my Deus is (so much so that in some places I couldn't even use the E-Trac) while the Deus saved the day at that particular site (or sites) many times ;-)

1 example is: there's a 1 room school house on a corner with a corn field next to it built in 1848 --- power lines (towers) run parallel to the property approx. 30 yrds to the east

the E-Trac is completely useless at that site -- will not operate at all due to the EMI interference of the power lines and there's no way to fix/avoid it

but

the Deus will run 100% quiet (not saying there's no interference whatsoever) but - it runs as though the power lines aren't even there and I have found upwards of a dozen Indian heads (as well as other things) in that corn field thanks to the Deus -- and/but -- "nothing" thanks to the E-Trac/FBS machine

just another example of why you can't have/own/use just *1* machine

PS

could always run my Gold Bug there too - which is why you need at least 1 high freq. machine in the tool shed

Must be your MD MRH. I run mine down what used to be a trolley rail in 1920 Charlotte and the power co has used it for a path for the large power towers. Stable as can be even with the 13" Ultimate. Couldn't use the GBSE or the G2 at that site at all. When I ran the ET 705 it had some issue with it but was able to get it under control with several adjustments and a smaller coil. Could use the CZ3D but the iron at that site made it a bad choice. Yes it does affect lots of other MD's when close. Our club holds an annual seeded silver hunt for members only and you should hear the language when I get close. Too funny. Affects 90% of the MD's. There are several others using the ET and we get together and "balance" them so as to not affect each other. Only ones that it didn't seem to bother were the Tesoro's and the F75 that could adjust for different frequencies.

I certainly had an ancient field where it was impossible to use my e trac, but the fisher f75 worked fine. It was a site littered with large iron nails. I would have thought that the e trac
would have bettered the fisher under these conditions but it wasn't the case.

Hi,,I have an interesting update to this EMI thingy....I was researching some more on the park & factory in question...It seems that when the park opened their 20 some acre recreation spot in the late 1800's they did not have any electricity....The factory just happened to have a power plant for generating electricity and offered to provide them with electricity....I'm assuming they buried electrical cables underground through out the park to provide them with their much needed electricity....I'm also assuming that the underground cables just sit idle today and are no longer being used....So what I have now is just one big antenna network buried underground leading to and from to contend with....This kinda puts a whole new paint job on things...JJ

JJ, without electricity running through the cables I don't believe they will have any affect emi wise. If the cable is in detector range, you may be masked depending on depth and size of the cable. I wonder if the cable is a thick copper, hmmm.

Hi Ozzie,,,It's very,very plausible that EMI would and could take the underground cable route,which is now acting like a big underground antenna....I use to build TV & Radio Tracking etc. transmitters just for something to do....Even though most of the power was radiated out the antenna itself the waves always loved and felt comfortable riding on the overhead power lines....The actual radiated antenna signal in some cases was limited to 100 milliwatts...This should of been good for only a few hundred yards....But I actually could pick the signal up at about 4 1/2 miles away, just as long as I was under the power lines when I was checking for a signal....Now I have no idea what the actual source is that's causing my silent EMI. it could be anything like a computer,router,machine,alarm etc....I just know it's there....I think the audible/noisy EMI I get every day but Sunday scenario, is cause by a store about a quarter of a mile away, which just happens to be closed on Sundays...Perhaps it's their Lotto machine? But that noisy EMI at that location is definitively taking the overhead wire route....Thanks for your input....JJ

No kidding. Didn't realize that jj.....interesting. So anything metal will pick up waves from the air...and if you hooked up a receiver or some kind of scope to that cable, you'd get something? Makes sense, thinking about it.

Hi again Ozzie,,,The copper wire I find at a few of these spots is about the size of your pinky 1/4" + or - and is a solid single wire not stranded ....Sometimes I will get some pieces about two feet long and it's kinda heavy.....There's enough electromagnetic waves/energy being radiated through the air to light a small bulb 24 hours a day....It's relatively quite easy to build a device to capture/harness this type of energy....It kinda makes you wonder what the long term effect will be on humans being bombarded with this amount of energy on a daily basis....There's so much EMR present and it will continue to get worse....We really don't care about it or complain until it becomes EMI... I don't know about you but I'm going to start wearing a tin foil hat...LoL... JJ



Edited 1 time(s). Last edit at 02/21/2014 01:04AM by jimmyjiver.