F75se Nails and some iron sounding like silver

[ramer]

My F75se as with my other detectors will often give a silver sound from nails and some iron. After passing over the same spot several times usually it settles down and mostly indicates what it is, namely iron. But as I am moving along at a fast pace, these false signals stop me dead in my tracts until I can determine that it is a nail and not a quarter or dime. Usually after doing some pin pointing over the target, it will show up as iron both in the numbers and the sound when returning to discrimination mode. I've tried higher discrimination settings but I think this just makes it worse because I will hear high falsing sounds and no low sounds at all to tell me I am probably over iron.
Anyone have any techniques to get around this type of falsing? Can get pretty frustrating sometimes and really slows up the searching.

 

[Charlie P. (NY)]

Set your discrimination to 21 and use default mode. Sensitivity to 80 if conditions allow. Iron nails vanish

 

[kmyer74]

I use all metal,1 tone,bp,99 sens in iron infested sites and i have picked alot of good stuff out that way. Gotta keep your eyes glued to the screen but it works really well for me.

 

[TerraDigger]

Ramer, what are your searching for. Coins? Or any non-ferrous items mixed in with iron? What you are searching for will determine how to set machine to optimum.

 

[Steve O]

Kymer, how do you use all-metal in iron infested sites? What are you seeing on the screen? I would have to mute the headphones, with all the whining from the dozens & dozens of non ferrous targets.
There are better ways to utilize the 75 in high iron sites. But if that method pulls out the goodies for you, I applaud.

 

[SteveP(NH)]

The issue is caused because some pieces of iron have a very high conductivity and they wrap around from the bottom of the scale to the top. The highest a piece of silver will usually dig is about 94 for a silver dollar. So what you can do is to notch out 95 on up to 99. 95 is usually a hot rock and iron that wraps around is usually in the 96 to 99 range. This won't totally get rid of the high pitched iron as some of it will read even lower than 95 but it will cause some of it to be discriminated out and the rest will break up more making it easier to spot. If I am at all unsure of the target then I will switch to all metal and look at it in that mode too.

One other thing I have noticed is that the mineralization meter will usually show 2 or 3 segments when you are over an iron target. Another thing that can sometimes help is to watch the confidence meter as the numbers jump around. Sometimes it will jump up when the TID is in the iron range and drop down when they are higher up. I have dug a number of targets like this to see how accurate the confidence meter is and have satisified myself that it is acccurate enough to pay attention to. The problem with it is that a lot of the time it won't jump up at all on an iffy target.

 

[Steve O]

I have noticed as SteveP did, the fe meter spikes when over iron. Never thought of notching out 95 to 99, may be a good tip.

 

[TerraDigger]

Notching 95-99 is excellent advice. I wish my Omega had that capability....like my older White's unit does. The ability to notch for 'iron wraparound' can make all the difference sometimes between success and failure on particular iron rich sites.
Think about it for a moment...how many silver half's/dollars is one going to miss, versus the other lower denomination coins in a iron rich site? The odd's favor notching for coin retrieval in this particular circumstance.

 

[Cal_Cobra]

I rarely, if ever, get fooled by iron on my F75 LTD/SE.

Low discrimination and a slower swing speed is key IMHO, and I've been able to pluck many keepers out of the infamous bed of nails. There's a recent thread on Nasa Tom's site discussing exactly this using the F75 with some interesting tips. I typically run zero disc, 99 sensitivity (or as high as I can get away with), BP mode and 3 tone and have been happy with that, but the recent discussion on Tom's site suggests to use a little disc to knock out the tiny bits of iron (anywhere from 2-6), and if your sanatizing a site to dig anything about the disc break point.

Plug this search into google and it should be the first hit:

F75 LTD/SE MONOTONE VS ALL METAL ?

HH,
Brian

 

[ramer]

Yes, I have been reading hours worth of Nasa Toms's articles and tips and tricks and his tests and results. He definitey takes detecting to new levels. What I haven't seen him explain though is this apparent problem that the F75se seems to have with its over sensitivity to EMI. On one of his tests, one of his other detectors was not bothered at all with EMI and was reading dimes to 11 inches whereas the F75se in the same area was having lots of EMI problems. Seems there is as much of a battle with EMI on the F75se as there is in the battle of actually finding keepers. Quite often, his settings are an attempt to use settings to mitigate EMI in order to get the detector performing to its max. Are other powerful and sensitive detectives also victims to this EMI boggyman? Maybe that's why some people call the F75se a chatty katty.
Another thing I picked up involves using the disc settings. Someone on this threat suggested I set the disc to 21 on my F75se and the nails will disapppear. But in all the hours of reading Tom's postings, he is setting disc between 0 and at most 7. In fact, one of the goals Tom has is to try and get the disc to 0 without too much chatter. Now this is where I get really confused (I'm easily confused these days) Apparently the F75se is most sensitive at disc 0 if you there isn't too much chatter. Where I'm confused is that I don't see why there is a relationship to sensitivity or should be a relationship to sensitiviy based on the disc settings. On my other detectors, increasing disc just masks out more and more undesible objects, tabs, ferrious, etc, making the detector less and less sensitive to these targets but over all leaving the sensitivity just as strong with desirable targets. The opposite seems to be true with the F75se whereas the higher the disc settings the less sensitive it becomes to ALL targets. So if I did as someone here suggested, that is, set disc to 21 and it would make nails disappear, well, maybe that's because everything else is beginning to disappear as well. It becomes an "insensitive" and poor performing detector. I need to ask Tom some of these questions.

 

[WV62]

I know I will get a lot of flack over this, but I was having so much trouble with my F75Ltd that I was just about to put it in the closet and use something else. But I found if I just run one tone and back the sensitivity down just out of the noise it runs just fine.

I decided one day in the park that somethings got to give, either get it running or else. So I ran the disc up to max and set for one tone, I popped a silver dime right away and was moving along pretty good. Then I thought well I am at max disc so everything should be high tone anyway, so I switch to 3 tones and as stated above I was stopped dead in my tracks. I switched back to one tone, everything was fine again. I did this switch several times and it was the same every time.

So about all I can say is try one tone, I think that will fix your problem. Also run your disc wherever you want, no magic number.

Good luck,

Ron in WV

 

[ramer]

Thanks for the info WV62. That is strange. Why is the number of tones used related to the sensitivity of a detector?? Tom touched on this bizzare behaviour as well. This is indeed a different type of a detector for sure. There is a graph on one of Tom's posting showing the relationship between disc settings and sensitivity. It is pretty dramatic and telling. The higher the disc setting the lower overall sensitivity to ALL targets. Should this be happening? Is it a hardware or software design flaw or just a peculiar "enhancement" of the F75se making it a deep seeking detector, which it is of course, no one is disputing that this is a coin and relic monster, IF it is setup correctly. Just trying to get a handle on what is going on so I can get the max out of it.

 

[WV62]

In what I said I didn't mean to imply that the detector is less sensitive using one tone. I actually think the tone settings has nothing to do with sensitivity. You just don't hear all that chatter.

Now I haven't tested to see if the disc settings has anything to do with sensitivity to items. That shouldn't be to hard to come up with a test to prove it. I have put some pretty small gold under it in the je processor and it picks it up just fine, of course the disc needs to be set low for gold like 15 using the Je processor. The same gold in the other processors needs to run even lower disc like 6.

What I was trying to say about the sensitivity settings is pretty much a repeat from the manual as to how to set the sensitivity. Which is just back it down until the detector settles down.

Bottom line one tone is my key to making this detector produce and I am also confident that I am not just walking in the park and missing everything. Without the confidence in a detector you may as well leave it at home.

Hope this saves your detector from a long dark life in a closet.

Ron in WV

 

[kmyer74]

I only hunt civil war relics and im looking for brass and bullets. It is alot of noise but with the processor being so quick i just watch the screen and i see and hear everything. Its amazing at how fast the processor is. Ive tried using discrimination mode in iron infested sites but ive learned that i got alot of falsing that way. When in all metal i see it all and i have went behind my old etrac and pulled alot of goodies out that i missed with the etrac. What other way would you suggest trying in iron infested sites? Im open to suggestions. I know its noisy as heck but in all metal i dont believe theirs a machine out there that can do what the 75 does when it comes to picking out the goodies. Just my opinion.

Kymer, how do you use all-metal in iron infested sites? What are you seeing on the screen? I would have to mute the headphones, with all the whining from the dozens & dozens of non ferrous targets.
There are better ways to utilize the 75 in high iron sites. But if that method pulls out the goodies for you, I applaud.

 

[EtracTom-AdirondacksNY]

I got one recently and read up on Tom's info first. I crank sensitivity up to max 99 and set it to BP boost mode as it hits better deeper and ID's better acording to him and his testing and set it to zero discrimination.

Then FIRST go through the F1 through F7 frequency channels with the red mode button and trigger and find the one channel with the least ammount of EMI noise with the coil parallel and a foot or so off the ground to get the best operation and depth out of it. Then Ground Grab ballance it then start to either lower sensitivity down to a smooth operating with little noise setting, mine is at 25-30 runs pretty quiet there and with 3H tones to give nickles a high tone too and with zero discrimination it's deep as the lower the discrimination each setting from 5 down to 0 it increases the gain for increased sensitivity also. Going from discrimination 20 upwards it also increases the gain it says in the F75 manual, the factory setting is 15 or 10 a spot where there isn't any gain advantage hence not running the discrimination higher than 5-6.

OR he says after doing the first few steps and then Ground ballancing you can change the discrimination up one setting at a time to see where it quiets the machine down up to disc. 6 don't go over that if it's still noisy THEN turn down the sensitivity till smooth pretty quiet operation. He says there is a big difference between discrimination 4 gain and then going up to 5 which lowers the machines gain sensitivity and then a good change again between disc. 5 gain going up to disc. 6. lower gain yet again. Says don't go higher than 6 disc. just lower sensitivity at that point down from 99.

Hope any of this helps out.

 

[ramer]

Does anyone have any idea how much the frequencies change in going from F1 to F7? I believe the default frequency is 12khz and is located on F1. Remember though, even though the machine saves all setting when you power it off, it doesn't save the new frequency setting. It reverts to F1, the default frequency on a power up. Just a heads up on this.
EtracTom, I read pretty much the same articles. This NasaTom is in a class of his own. Really helpful articles by him.
By the way, how do you like the Fisher 75ltd? Is it much different than the etrac? I never even held an etrac or seen one in use. But I know lots of people rave about them.

 

[EtracTom-AdirondacksNY]

Thanks for the cudos and if I'm not mistaken friend F4 is the factory default on the F75 please check your manual.

I'm sure when you change to other F channel numbers it is a very small amount like maybe from 13khz to maybe 13.1 khz or 12.9 khz then a bit more as you get away from F4 down to F1 or up to F7 but I think it's still within a one number range like maybe close to 12khz at F1 to maybe 14 khz at F7. maybe Dave J. will chime in here.

Yes it's a bit different than the Etrac both are great machines. I am glad to have both and a couple more others that I own to be able to switch between when and if I want to depending on mood I'm in or at areas/location or what I'm hunting for specifically.

 

[Cal_Cobra]

I know I will get a lot of flack over this, but I was having so much trouble with my F75Ltd that I was just about to put it in the closet and use something else. But I found if I just run one tone and back the sensitivity down just out of the noise it runs just fine.

I decided one day in the park that somethings got to give, either get it running or else. So I ran the disc up to max and set for one tone, I popped a silver dime right away and was moving along pretty good. Then I thought well I am at max disc so everything should be high tone anyway, so I switch to 3 tones and as stated above I was stopped dead in my tracks. I switched back to one tone, everything was fine again. I did this switch several times and it was the same every time.

So about all I can say is try one tone, I think that will fix your problem. Also run your disc wherever you want, no magic number.

Good luck,

Ron in WV

Ron that's a good observation. I don't know if I could hunt in monotone, but I did find at one remote site where I was getting some EMI/stability issues, when I switched to AM mode it was nice and stable, and because targets were sparse, it wasn't that bad running in AM, so I guess monotone would be OK given the right environment.

HH,
Brian

 

[TerraDigger]

I like monotone for cherry-picking with the Omega and the disc cranked to max like WV62 does.
Why? I get at least a inch (i think 1.5" is more correct) greater depth and the signal hits alot harder. Tested on coins I buried and its not my imagination. Does it slow me down a bit? Yes. Iron blips have to be investigated more thoroughly than if I was using a multi-tone.

 

[WV62]

I like monotone for cherry-picking with the Omega and the disc cranked to max like WV62 does.
Why? I get at least a inch (i think 1.5" is more correct) greater depth and the signal hits alot harder. Tested on coins I buried and its not my imagination. Does it slow me down a bit? Yes. Iron blips have to be investigated more thoroughly than if I was using a multi-tone.

I do most of my hunting in a local park and a few ball fields. I only hunt jewelry and coins, so I only have 3 setups.

All setups are monotone, and change coil size as needed.
For cherry a ball field, I run de processor, max disc, sometimes notch in nickels.
For older coins, I run boost processor, and the same as above.
For jewelry, I run je processor, disc set @15, and notch out zinc's. Note: I like the little 3 1/4 x 6 1/2 elliptical for jewelry hunting.

Ron in WV