Question on Performance during EMI

[iskirkra]

I have been hunting where an old town was located about 70 years ago with the LTD. There is nothing left of the town and there is not a house within a mile, but there are power lines and transformers running oil wells all over the place. I can't stop the constant chatter even going down to 50 on sensitivity. The fe304 is running about .01 to .1 which is not to bad. I can hold the coil up in the air and it is constant chatter and the same when you sweep on the ground. I can still pick out targets, even though it wears you out. My dad is running an F2 and having the same problem. My question is, does EMI like this affect performance. Do you get less depth with all this going on? I have never encountered EMI this bad even in town. Thanks Randy

 

[marcomo]

I've been fortunate to only have this happen in one spot with the LTD so far.

At that point you gotta bite the bullet and turn the sensitity significantly lower.

Below 30 is a lower gain level, go below 30 if you need to. Even with low sensitivity settings you'll get good depth.

Try changing the frequency, sometimes that will help a little.

A smaller coil will usually help too.

 

[Cal_Cobra]

I'd be curious to see if running with a sensitivity of 29 (low gain mode) will mitigate this. Let us know how it goes.

 

[iskirkra]

Thanks for the responses guys, I forgot about the "below 30" sensitivity putting it in the low gain mode. It goes against your nature to lower the sensitivity that much. It will be the weekend before I can get back out but will give it a try and report back. Thanks again for the help.

 

[boxofchocolates]

Randy I don't know if this will help but I'll share it with you....When I was real new to the f75ltd (my first fisher unit) I was at an old and still active school from the 40's it has been detected for the last 35-40 years I wasnt used to the noise. At the area of the school I was detecting there was severe interferance from elect. or under ground piping....I turned the sens down to 4.....yep......4......I found I believe 1941 quarter and 1935 buff. nickel shortly after they hit hard not to deep 3-5 inches but it had power and was quite.It made me wonder how it may effected others detecting there...surely they would have hit on them....but maybe the interferance messed them up but I had a powerhouse detector f75-ltd in bp process disc about 15 their loss my have been my gain.....just my thoughts on this unit......I don't recommend these low sens. setting but you got detectable options with this unit.....my point here don't be affraid to tone it down you my be super suprised I was.

 

[Elton]

n/t

 

[mikewaz]

That's good to hear!
I was at two sites this past weekend and had quite a bit of EMI that kept me away from some areas I wanted to hit. Some of those spots looked great but close to the road and the power lines,
I figured I'd grit my teeth, drop my sens to 60 and go for it, but that didn't last too long. If I got within 50 yards of the power lines the chatter drove me nuts.

Now I want to get back out there and try it again at sens 29 because I know that chatter kept everyone away, and they were both very old sites that should have plenty of keepers left.,
Have fun!
Mike

 

[jim tn]

The 29 sen. does work. I, however, have never dug anything deeper then 5-6," so don't know just how deep that setting actually is. HH jim tn

 

[markg]

You must have the red clay dirt to dig.
That's the way it is in Virginia.
Very few coins deeper that 6-7" deep.

 

[jim tn]

My dirt over on this end of the state isn't to bad. For the most part, feo is .03 and fastgrab gb in the low to mid 60's as the norm. I've dug a good many coins in the 8-10" depth range and a few a little more with both the F 75 and F 75 LTD. I have not had to go to the 29 sen. setting much so don't know how deep it actually is in my soil. Or, if perhaps the 29 setting isn't as deep...and or, how much emi effects that setting's depth. None of us like the chatter effects of emi, but at least we know when emi is taking place and can try and make adjustments. I've hunted with some guys that said emi wasn't a problem with their detectors and my F's were chattering away. After making adjustments on my F and digging some coins they passed over, they began to realize emi was effecting their detectors, but they just didn't know it. HH jim tn

 

[boxofchocolates]

Jim,That would pretty much describe the situation I mentioned above,thats why the quarter and buffalo nickel were still there and not very deep ...but we have adjustments we can make and I did, quite as a mouse and finding coins.....hh........Dan

 

[iskirkra]

Well, I had hoped to get back out to the EMI field this weekend and play with the sensitivity below 30, but it has been raining since Friday. I live in North Texas and we have had more snow and rain this year than I can ever remember. Hope next weekend is better.

 

[tvr]

Daughter's softball double header yesterday gave me chance to walk a grass parking area with the LTD. I had not been to this field before. High tension tower line right over the parking area and adjacent path areas. The kicker was that I had to drop sensitivity to 18 to get fairly quiet. Ground balance over most of the area was right around 65 with Fe3O4 at 0.1. Got a clad dime at 6 inches and a wheat at about 6.5 inches and various other clad shallower than that. Got a dozen beaver tail type pull tabs in the 4.5 to 6 inch range. All solid hits and not iffy zip sounds.

Had an area that looks like it was a spread out pile of infield fill dirt ... they like a little sand mixed with and orange color clay for the infield fill. This GB'd at 47 with Fe3O4 bouncing between 0.3 and 1. Two pennies; one an inch down the other about 3 inches. Very solid hits so don't know how deep I'd see in the clay.

So does the LTD do a good job near EMI sources with the sensitivity set low? Personally, I think it does.
tvr

 

[iskirkra]

tvr, thanks for the report and that sounds promising in areas with really bad EMI. I can't wait to get back out to my bad EMI location and give it a try. 6.5 inches with the sensitivity at 18 is great. I am learning more about the LTD all the time and one thing I am learning is that the LTD really gives you lots of options in different conditions.

 

[tvr]

The ID numbers were pretty good too; only varying a number or two on the coins. More variation on the tabs as they were bent in different ways, so it is expected. Ground was pretty mellow except where the infield fill was. I've found I like working BP mode at a leisurely pace. Seems to suit me and the detector in that mode.
Hope your's works well for you in your EMI area!
Cheers,
tvr

 

[iskirkra]

Well I finally got to go back to the EMI field on Saturday. I ran the LTD at 28 sens and 6 disc and was able to hunt for several hours and not have my brain fried. It is amazing that you can lower the sensitivity that low and still find stuff. I found a good spot at about the time I needed to leave and found where I think one of the tent homes was located. I found the brass tent rope tensioner and the tent grommet and then the other items near the same place. I don't know if the gun is real or not it is in bad shape, It is really heavy but could be a toy, not sure. I found several of the old ball jar lids with the ceramic insert, those are cool. I found the jar lids at about 7 inches. Now that I have found a place where i think one of the tent homes was located I need to go back and really work it. Thanks for all the advice.

 

[tvr]

Nice!!! I like finding the zinc rim, porcelain lined jar lids. They don't do a lot to help date things since they were produced over a fairly long period, but if you find those, you are likely to find some silver.
tvr