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Re: F70 users! My Brother Gave me A Homework Assignment
Posted by: MarkCZ
Date: March 25, 2017 09:26PM
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NCtoad
Hey Mark,
I did some airtests with my F70 not too long after I got it and from what I remember positive thresh settings were deeper up to a point like +3 and from there on up the returns were less and less. Lately I've been hunting almost exclusively in negative thresh, usually -1, but sometimes -2 and -3. This with sensitivity at 40-60 and sometimes even lower. I've hit copper cents at a measured 7" in dirt that ground balanced in the 60's. Threshold in DE mode is sort of mystical to me.

From my testing so far and your results I'm thinking that for you a -3 threshold and a 60 sensitivity you should be able to go to SL mode and gain a near 2" more depth and still be out of the detector noise range.

Mark

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Re: F70 users! My Brother Gave me A Homework Assignment
Posted by: MarkCZ
Date: March 25, 2017 09:36PM
Quote
dfmike
Gaining 2.25 inches with a tiny variance of 1 on the threshold control is uncanny. Did you try +2 and so on just to see how it would vary onward with positive threshold ?

Is the F70 the only detector to have threshold control in disc (compared to the F75 and T2) ?

"dfmike" I found the below in the Teknetics T2 manual and its called "Hum Level" LoL! Seems they included it in the T2 but decided to give it another name.

Quote
T2 manualHUM LEVEL This is the same thing that some manufacturers call audio threshold. It is
adjustable from -9 to +9. For maximum ability to hear the weakest signals, adjust this
background hum level high enough so that it is barely audible while the detector is in use in
the field. To eliminate the weakest signals, adjust the hum level into the negative region,
which will allow the machine to run silently if the Sensitivity is not set too high.
The hum level changes slightly with each detent step on the Settings knob. Each number
on the hum level numeric readout corresponds to five steps.[/quote


Mark


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Re: The Chart Is Here, it may still get some more work.
Posted by: MarkCZ
Date: March 26, 2017 12:41AM
The green is where the detector was starting to have false responses, but not enough to be able to pick out the target response.

The red, is where the falsing got to bad t clearly pick out the target responses.

The random boxes that have the additional SL=XX number are point where I used the chart settings but switched to the SL mode.

Down the far left column for the threshold numbers we included the term Not Modulated and Modulated referring to "Modulated" and "Not Modulated" audio (not including the extra SL mode test)




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Re: The Chart Is Here, it may still get some more work.
Posted by: REVIER
Date: March 26, 2017 08:09AM
Thanks Mark for all the info and interesting data.
As you said in the real world results can be different so a couple of experiences...

My deepest coins I ever dug so far were in good soil in Kansas but the site had some issues.
At the edge of a big park that always had horrendous EMI problems constantly and every time i hunted this area.
More thrumming, pulsing problems than any site I have ever bern to before or since.

Large DD, sense at 80, thresh at -1, DE speed, 4H tones, disc not sure but might have been about 6 but could have been as high as 22-23.
Lots of jumping around but the F70 still stopped over targets to give me indications something was there and those weren't false signals.
I got a pretty jumpy signal that ranged from the 50's to almost 80 over a large area about a foot square and the depth says 7-8".
With all that EMI causing jumping and the large area I usually would have passed this by but those range of numbers somewhat repeated as I ran the coil around the area and the kicker was the tone sounded great, solid and sharp here and there as I moved the coil around.
This got me to dig and I come to find out this was a coin spill that was 3 Indians and an old wheat, so the number range was correct, and most were at least 8" but at least two were deeper closer to 10".
Wish I would have bumped the thresh into the positive at the time but this was early on in my experimentation and didn't think to do that.
I thought this signal was some sort of junk at the time, anyway, how was I to know these were coins?

In that same park more in the middle away from all that EMI I dug my deepest target ever.
This one was in the red on your chart all the way to the corner so if you could set settings to this level I believe you would have found some shocking double digit numbers there.

Same big coil, disc in the low 20's, sense 99 and thresh at +9, 1F tones and in this spot these were relatively quiet.

Mark, I must mention again in areas with EMI the lower tone choices do seem to handle it better than the higher ones...1, 1F and 2F are more stable than multi tones or DP from all my experiences which is why I asked you to test in monotone.
It might not matter in your home doing this testing but in the field it just might.

Using these high settings I easily acquired a few targets deep, mostly tabs at 6-8" and then a small bell like off of a cat or dog collar at about 9"...then I got this one.
Sounded pretty solid, saw numbers go from the mid 20's with a jump or two to 40 but they repeated from all angles and I saw 23-26 numbers repeat more than any others.
When I hit the pinpointer I was shocked to see 13-14" numbers on the screen and they stayed there every time I came at this target from every angle.
I never dig this deep in public parks but this one I went after just to see if anything was actually down there that deep.

We all know that on this platform the audio goes deeper than the screen, it is like the audio is always in all metal but the screen in disc can't match it on the really deep stuff at the very end of the scanning field so it gives up and just goes blank.
I dug several beaver tail tabs at 10" before that usually have a high tone when that deep using the 10" elliptical concentric and a few had screen info but most had that blank screen
This I had never seen before, a target that deep with good audio and screen info so my curiosity was piqued.
I checked the signal with blown out maxed all metal and got the same numbers and good tone so I dug.
This wasn't a coin but a thumb ringer off of an old bicycle bell so a bit bigger but still there was something down there so I was thrilled.
I measured this one...every bit of 15" deep and to have screen info on this thing astounded me.
Checking it out of the ground this was a solid 23-25 signal so the screen info was fairly accurate even that deep.
I believe it was that maxed thresh and sense in disc that enabled me to see it and it easily matched the all metal depth.


Here is a post I wrote up in an F70 log I was putting all my experiences in 3 years ago and I will just copy and repost it here and it goes along quite well with your testing results although I never went past 0 on the thresh.
Wish I would have now because positive numbers could have been good data to gather but I was going by what sounded good to me as a diggable signal at the time.
This pertains to a real world target using low sense and playing with the thresh on a measured 5" dime I came across.
I mention the weird sound as thresh was pushed higher...that modulation that you seem to like but I don't because I prefer a more solid sounding tone which doesn't matter because as long as any settings work for us those are the correct ones.
On this one SL speed did matter.

Starting settings were bid DD coil, DE, 4 disc, -3 thresh, 4H tones and sense on 30 which fools that big DD coil into thinking it is a scalpel-like sniper coil.
I wanted to get an idea on how deep low sense could get me when using sense at low levels when hunting in trashy areas.

I titled this post...."19"...


--------------------

A Jr. College right near my house.
Been here a million times, took a ton of clad when I first came here but not a whole lot left, 3 gold rings from different areas so far too.
Just wanted to see if I cold still find clad I left behind in the past.
All settings were where I left them from the last hunt.
Disc was lowered to 4 because I still want to find the tiniest chains, everything else was left alone except thresh was lowered to -3, DE, sense at 30, 4H tones, notch always at 1.
Zip, zip, zip, found some coins pretty easily, a few pieces of trash, avoided most other trash that was jumpy and so on...a nice short but productive hunt.
These settings are excellent for shallow coin and jewelry hunting, I will probably keep them around but still not sure on the depth they will go.
Now I will get to that 19 thing.

Near the end of this hunt I came across a dime signal.
Solid 78, no jumpy numbers at all, solid tone and numbers from every direction, the depth reading said 5" deep and there was no trash or other signal near it.
This was the one.
I knew it was a dime with every fiber of my being, hoped for a silver ring but 99.9999% sure I had a dime under my coil.
I stopped and played with this awhile with every setting I could think of to figure out a little more about depth on low settings.

The sense was still on 30, I started lowering down the sense while swinging in short passes over this thing.
When I got down to about 23 it started breaking up a bit, at about 21 it became a signal I would not dig anymore.
Also something weird happened when I got to about 24 or 25 while it was still a solid signal I would dig, the high tone in 4H changed and became weird sounding.
Very weird sounding.
Still solid, still repeated, but it was not full sounding at all like half of the tonal qualities just went away.
Hard to explain but I didn't like it.
At that point I started adjusting the thresh and moved it from -3 to -2.
The tone got a bit louder but still sounded weird.
Then I went to 20 on the sense and I lost the signal completely.
It was gone.
I moved the thresh up one notch to -1 and it came back again, solid and repeating but still weird sounding.
Thresh back to -2 gone, up to -1 back...I did this several times.
No breaking up or iffy signal at any time during this, it was just like a wall went up at -2 and went down where I got a signal again at -1.
Strange.
I moved it up one more notch to 0 and it was a bit louder and I left it there.
Then I switched from DE to SL at this point and the signal came back, sounded clear and full, and everything was all right with the world again.
The 78 number stayed solid and stable throughout all of this except when the tone went away completely and then the number did too.
One more thing to do.
I lowered the sense one more number to 19 and the signal was still there in all its glory, one more move down to 18 and it was totally gone again.

Ok, lets take stock of what we have at this point.
Thresh on 0, 4H, SL, Sense at 19, Disc on 4, dead quiet, no falsing or extra noise at all and by scraping the coil on the ground I was picking up a for sure dig me dime at a supposedly 5".
Impressive!
Now these are the kind of things I need to know to give me confidence in hunting at really quiet settings at or even below the factory start up 60 and still feel I can find deeper coins at 7-8" or maybe a bit more if I had to.
Not sure I will ever do this but it is nice to know I could if needed.

At that point I picked up the coil 1" off the ground, swung and the signal was gone.
If this thing really was at 5" this was the limit in my ground at these settings.
I turned the sense back up to 30 and I could raise the coil another 2 inches or so and still get the signal solid.
That would be 7" on 30 sense.
I turned up the sense to 40 and I could raise the coil 2 more inches and still get that solid signal every time I passed the coil over it.
9" on 40 sense.
Up to 50 on the sense, two more inches on the coil upwards, 11" on 50 sense with 6" air and 5" in the ground and that was all I needed to know.
Talk about confidence building!

All that was left now was to dig the coin.
I opened a hole, dug down slowly, got to the coin which of course was a dime and I took out a small plastic 8" ruler I get free from my bank and stuck it in the hole and put it right where the dime was laying.
looking sideways across the top of the hole at the very edge of the grass where I was scraping my coil I saw the number 5 on the ruler.

Alrighty then...this is data that I can use to my advantage!

------------------

So in the real world higher thresh can help in not only unmasking good targets around iron and trash but in the area of depth under all kinds of circumstances.
It is not only there to mitigate chatter or to locate tiny targets but also for depth.
A million ways to set this thing up...I am trying my best to try every one I can think of and put it down somewhere until I can't lift my detector anymore.



"What if doing the Hokey Pokey really IS what it's all about?”
F70, F2, Compadre, Mojave, Judge2 - 2017....Clad, 13 silver targets including a freaking Barber quarter, a beautiful walker and two V nickels...
Plus other cool stuff.




Re: The Chart Is Here, it may still get some more work.
Posted by: NCtoad
Date: March 26, 2017 08:21AM
Quote
MarkCZ
The green is where the detector was starting to have false responses, but not enough to be able to pick out the target response.

The red, is where the falsing got to bad t clearly pick out the target responses.

The random boxes that have the additional SL=XX number are point where I used the chart settings but switched to the SL mode.

Down the far left column for the threshold numbers we included the term Not Modulated and Modulated referring to "Modulated" and "Not Modulated" audio (not including the extra SL mode test)

Mark, thank you so much for doing this! That is a great chart!! I've suspected these results (mid level sense and mid level thresh for best depth) from the little bit of experimenting I did. I also noticed I got the best signals in my test garden with mid level settings. At the time and being a newbie I just figured higher sensitivity would lead to better depth. Now there may be certain soil conditions where higher sense will lead to deeper signals, but it does't seem to be the case in my soil where I'm ground balancing in the high 80's to low 90's. High sense (80 and above) seems to give a low level feedback in my headphones. Can I have permission to copy your chart and post it on the F70 user group over at FMDF?



Edited 1 time(s). Last edit at 03/26/2017 08:23AM by NCtoad.

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Re: The Chart Is Here, it may still get some more work.
Posted by: MarkCZ
Date: March 26, 2017 09:16AM
Quote
NCtoad

Mark, thank you so much for doing this! That is a great chart!! I've suspected these results (mid level sense and mid level thresh for best depth) from the little bit of experimenting I did. I also noticed I got the best signals in my test garden with mid level settings. At the time and being a newbie I just figured higher sensitivity would lead to better depth. Now there may be certain soil conditions where higher sense will lead to deeper signals, but it does't seem to be the case in my soil where I'm ground balancing in the high 80's to low 90's. High sense (80 and above) seems to give a low level feedback in my headphones. Can I have permission to copy your chart and post it on the F70 user group over at FMDF?

Sure, I posted to share with anybody that could make good use of it.!

Mark

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Re: F70 users! My Brother Gave me A Homework Assignment
Posted by: MarkCZ
Date: March 26, 2017 10:23AM
Seeing how there is some interest in the sharing of my F70 chart I'm going to try another screen shot of it and see if saving it as a PNG file instead of a JPG helps the quality of it some,
it's the same chart in that the contents hasn't been changed.
So, will see if this looks any better.

Well, I checked it after it uploaded and to me it looks pretty much the same as the other, which is just a bit fuzzy for some reason, when I view it directly from my computer file the image is perfect.

Mark



Edited 1 time(s). Last edit at 03/26/2017 10:28AM by MarkCZ.




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Re: F70 users! My Brother Gave me A Homework Assignment
Posted by: REVIER
Date: March 26, 2017 11:45AM
Both look perfectly sharp and fine.
Methinks your eyes might be a bit fuzzy.
Or... :drinking:



"What if doing the Hokey Pokey really IS what it's all about?”
F70, F2, Compadre, Mojave, Judge2 - 2017....Clad, 13 silver targets including a freaking Barber quarter, a beautiful walker and two V nickels...
Plus other cool stuff.

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Re: F70 users! My Brother Gave me A Homework Assignment
Posted by: WV62
Date: March 26, 2017 12:02PM
You tell him Revier, :rofl:



Worked and lived in the Huntington West Virginia area all my life, retired 2010
US Air Force Vietnam Veteran (68-69 & 70-71)
Started getting into metal detecting around 1975

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Re: F70 users! My Brother Gave me A Homework Assignment
Posted by: REVIER
Date: March 27, 2017 09:32AM
Here ya go...

Hunted yesterday all over a small park I have been to many times over the years.
F70 had the big DD coil, sense at 65, thresh on +4, DE speed and 3H tones the whole day.
Stayed pretty quiet and scored all the coins below in areas I had hunted before.
Nothing super deep and I can't say these settings made a huge difference and I can't say I never got a coil over them before for sure but they were all pretty easy to spot from a couple of areas I had scoured pretty good many times.
None were ever gridded though, I just do my drunk aimless wandering thing at most of my sites and hope for the best.
The two coins on the left of the pic were the good ones...a mid 40's and mid 50's wheats but where I found them was the good part.
A small front lawn area of an old knocked down home and I know I have hit this small area a lot pretty carefully paying close attention with all kinds of detectors, coils and settings looking for masked silver coins.
This time they were easy to find.

Some nice black dirt on top but just a few inches down some thick red clay, some trash in the area and some kind of big iron down deep under one of them.
They both showed up at the 4-5" depth level, bouncy into the high 80's to low 90's like coins usually do around here but they repeated from 2 angles with no drops down to the 70's or 60's like rusty bottle caps usually do or even once to iron like iron usually does.
Like I said it was pretty easy...this time.

Could it have been the higher thresh settings?
Usually hunting in this spot in disc my thresh more often than not is set at -2 or lower.
I think I have also tried my blast through all metal with sense and thresh maxed settings at least once here, maybe, but they stayed buried till yesterday.

Looks good so far...I will continue to maybe tweak a bit more and hunt more of my usual sites and see what happens.
Maybe try monotone next, seems to have some superior unmasking abilities around here or at least helps me notice good signals even better than multi tones.



"What if doing the Hokey Pokey really IS what it's all about?”
F70, F2, Compadre, Mojave, Judge2 - 2017....Clad, 13 silver targets including a freaking Barber quarter, a beautiful walker and two V nickels...
Plus other cool stuff.



Edited 3 time(s). Last edit at 03/27/2017 09:39AM by REVIER.




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Re: F70 users! My Brother Gave me A Homework Assignment
Posted by: dfmike
Date: March 27, 2017 10:15AM
Quote
MarkCZ

"dfmike" I found the below in the Teknetics T2 manual and its called "Hum Level" LoL! Seems they included it in the T2 but decided to give it another name.

Quote
T2 manualHUM LEVEL This is the same thing that some manufacturers call audio threshold. It is
adjustable from -9 to +9. For maximum ability to hear the weakest signals, adjust this
background hum level high enough so that it is barely audible while the detector is in use in
the field. To eliminate the weakest signals, adjust the hum level into the negative region,
which will allow the machine to run silently if the Sensitivity is not set too high.
The hum level changes slightly with each detent step on the Settings knob. Each number
on the hum level numeric readout corresponds to five steps.[/quote


Mark

Thanks Mark. I went on the Teknetics site and on page 11 of the T2 manual they state that the hum level or threshold is in the all metal mode. No mention of it in the disc mode like I thought. It does have a threshold control in all metal but NOT in disc. So it does appear that the F70 is the only one to have it in both modes among the 13 kHz machines. It's something I like having on the F5 and if I ever decide to try a 13 kHz machine that could sway me towards the F70.



Active detectors: Fisher F5 , Fisher F19 LTD, Nokta Fors CoRe, Makro pointer and way too many coils.
Previous detectors: Bounty Hunter Discovery, Fisher F44, Omega 8000 V6, Minelab X-Terra 705


Re: F70 users! My Brother Gave me A Homework Assignment
Posted by: hsimmons75
Date: June 03, 2017 04:56PM
I read this thread and another that i believe was posted by Revier either here or on another forum. I noticed that the depth on both charts seemed to max out with the thresh set at +2. I decided that I would hunt my yard which has been scoured and a local picnic grounds that I had done pretty good at last week. I set my thresh to +2, 4h tones, De process, disc at 65 with nickels notched in. I adjusted the sensitivity based on the chatter from 35-80 throughout the hunt. I had great success. i found two coins a wheat and a dime at 8+ inches. All coins hit hard. The picnic grounds was littered in pull tabs, but I just had dig a few to be able to tell the difference.If anyone knows where to locate the charts from Revier, please let me know so that i can download them. I don't mean to resurrct an old thread, but these settings worked wonders in soil that GB's in the 70 range. Try them out and see if you get the same results.

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Re: F70 users! My Brother Gave me A Homework Assignment
Posted by: REVIER
Date: June 03, 2017 07:43PM
Quote
hsimmons75
I read this thread and another that i believe was posted by Revier either here or on another forum. I noticed that the depth on both charts seemed to max out with the thresh set at +2. I decided that I would hunt my yard which has been scoured and a local picnic grounds that I had done pretty good at last week. I set my thresh to +2, 4h tones, De process, disc at 65 with nickels notched in. I adjusted the sensitivity based on the chatter from 35-80 throughout the hunt. I had great success. i found two coins a wheat and a dime at 8+ inches. All coins hit hard. The picnic grounds was littered in pull tabs, but I just had dig a few to be able to tell the difference.If anyone knows where to locate the charts from Revier, please let me know so that i can download them. I don't mean to resurrct an old thread, but these settings worked wonders in soil that GB's in the 70 range. Try them out and see if you get the same results.

Nope, no charts from me, MarkCZ is the chart guy around here, if you can imagine it he has made up a chart about it.
Don't know how he ever gets the time to hunt in between setting up all the testing, doing the testing, recording results then manufacturing the actual chart.
In full color no less.

A real asset to the forum, that guy.



"What if doing the Hokey Pokey really IS what it's all about?”
F70, F2, Compadre, Mojave, Judge2 - 2017....Clad, 13 silver targets including a freaking Barber quarter, a beautiful walker and two V nickels...
Plus other cool stuff.



Edited 2 time(s). Last edit at 06/03/2017 08:02PM by REVIER.

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Re: F70 users! My Brother Gave me A Homework Assignment
Posted by: MarkCZ
Date: June 03, 2017 09:01PM
Quote
REVIER
Quote
hsimmons75
I read this thread and another that i believe was posted by Revier either here or on another forum. I noticed that the depth on both charts seemed to max out with the thresh set at +2. I decided that I would hunt my yard which has been scoured and a local picnic grounds that I had done pretty good at last week. I set my thresh to +2, 4h tones, De process, disc at 65 with nickels notched in. I adjusted the sensitivity based on the chatter from 35-80 throughout the hunt. I had great success. i found two coins a wheat and a dime at 8+ inches. All coins hit hard. The picnic grounds was littered in pull tabs, but I just had dig a few to be able to tell the difference.If anyone knows where to locate the charts from Revier, please let me know so that i can download them. I don't mean to resurrct an old thread, but these settings worked wonders in soil that GB's in the 70 range. Try them out and see if you get the same results.

Nope, no charts from me, MarkCZ is the chart guy around here, if you can imagine it he has made up a chart about it.
Don't know how he ever gets the time to hunt in between setting up all the testing, doing the testing, recording results then manufacturing the actual chart.
In full color no less.

A real asset to the forum, that guy.
WAIT!!!
My big brother WV62 is the real chart creator!! he'll send me a chart or ask me for some numbers to fill in some blanks on what he's working on. I think he makes a lot of them up during the winter, then he (we) refines them as he goes along.
Being new to the forum I don't know if you can send personal message yet, but if you can look at WV62 post above and send him a message I'm sure he'll send you any of the charts he has. If you can't do PM's yet then you you could post your email address in a reply in this topic and he'll probably fix you right up.

Mark

.



Avatar, Me and my two brothers from left to right!

WV62 - MarkCZ - Still Looking 52

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Re: F70 users! My Brother Gave me A Homework Assignment
Posted by: WV62
Date: June 03, 2017 09:32PM
My email address, rwcapron@suddenlink.net if you need a chart I will do my best to send you the one you want.

Ron in WV



Worked and lived in the Huntington West Virginia area all my life, retired 2010
US Air Force Vietnam Veteran (68-69 & 70-71)
Started getting into metal detecting around 1975

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