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F70 users! My Brother Gave me A Homework Assignment
Posted by: MarkCZ
Date: March 23, 2017 10:41PM
First!
I spent an evening doing air test, in the house! and everybody knows that air test depth measurements DO NOT CARRY OVER TO REAL IN THE EARTH DEPTH!! and were not trying to say it does.
But! for silver coins there isn't anything about DIRT that would make the detector have greater depth than AIR!.

Next,
I want this thread to be more than just depth, I've already discovered some things about my F70 that I didn't know and that I didn't see in the manual. So, I'm hoping that some other F70 users will do some confirmation testing to see if these things carry over to ALL F70's.

I may have been able to run higher settings in an environment with less EMI, I did shut down my computers and cut the power to my WIFI.

Okay, here is one thing I found in my testing,
I used DE mode,
I used the 11" DD coil.
Test target was a US Silver Dime.
I started out with the sensitivity @ 25 and a -5 threshold and repeated the test by moving up the threshold step by step and recorded depth at each.
-5 = 2.5"
-4 = 3.0"
-3 = 3.25"
-2 = 3.5"
-1 = 4.0"
0 = 4.75
To this point all is well, but the next step sort of stumps me (well surprised me), take a look!
+1 = 7.0" (WoW, almost like boost)

There is a couple of things other than just the big jump at the +1 threshold! First thing is that up to that point the detector didn't have modulated audio!, but as soon as I reached that point it had a really SWEET modulated audio. Anybody else know about this? (or does your F70 do that?)


Mark
-



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

WV62 - MarkCZ - Still Looking 52



Edited 1 time(s). Last edit at 03/23/2017 11:03PM by MarkCZ.

Re: F70 users! My Brother Gave me A Homework Assignment
Posted by: After-1-
Date: March 24, 2017 12:21AM
Wow, Thx for that info ------------------------------after1-------------------

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Re: F70 users! My Brother Gave me A Homework Assignment
Posted by: REVIER
Date: March 24, 2017 12:35AM
Hitting a coin at 8" with high thresh but sense on...1.

There is a relationship between the sense and thresh for sure, I have tried this high thresh lower sense thing in my rough dirt at the local park and on targets I checked it seemed to be as deep as any of my other deepest settings but I rarely use that....I turn the sense as high as I can to areas without a ton of noise if only for peace of mind.

Using multi tones the sound starts changing at -1, skews into weird areas I don't like which might be that modulation you are talking about.
I prefer the more solid, sharp sounds in multi tone.
At 0 and past into positive numbers this weak sound really drives me nuts but using 1 monotone it really isn't noticeable all the way up the scale.

The deepest target I ever dug was at 15" with the sense and thresh maxed...could be it was the high thresh that did it but I never played with the settings on that one.

This is one of the advantages of using the F70...control over the thresh in disc.
Great things can happen with all sorts of settings and high disc does appear to have some pretty good unmasking properties too.
I have done his homework assignment out in the field, got a high mark and a silver star on the paper.
http://www.findmall.com/read.php?37,2346907,2346907#msg-2346907



"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 03/24/2017 11:13AM by Elton.

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Re: F70 users! My Brother Gave me A Homework Assignment
Posted by: MarkCZ
Date: March 24, 2017 07:44AM
Revier, this isn't my first detector that had an adjustable threshold, my coinstrike did as well, but it never had spot where the depth jumped that much.
As far as the modulated audio most of my detectors in recent times have had that, this is something I guess you get use to, but I like the far away sound (faint) when the target get farther away from the search coil.

Later on when I have more time I'll chime back in with another discovery I found in the + threshold range.

Mark

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Re: F70 users! My Brother Gave me A Homework Assignment
Posted by: dfmike
Date: March 24, 2017 08:47AM
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) ?



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

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Re: F70 users! My Brother Gave me A Homework Assignment
Posted by: WV62
Date: March 24, 2017 09:21AM
I am kind of thinking the F5 has threshold control in disk, I done the same testing on a F5 a couple of years back. I sold that F5 to my brother Greg (Still Looking 52 forum name) and he is still using the same settings I gave him.

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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Re: F70 users! My Brother Gave me A Homework Assignment
Posted by: REVIER
Date: March 24, 2017 09:42AM
This was a mistake...
"Great things can happen with all sorts of settings and high disc does appear to have some pretty good unmasking properties too."
I meant high thresh, not disc.

The F70 is a wonder and I have said that several times.
A ton of settings, many will accomplish the same goals with great success, others just make it all easier to notice the great targets in trash, iron or mineralization.
I keep trying different things, try to get good at using them and then file them away for future use in sites with different conditions.
You never know what will come in handy.



"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: still looking 52
Date: March 24, 2017 11:46AM
The f5 does have theshold adjustment in disc mode, this I know for sure. I usually run around -2 and that seems to compliment the disc settings for good coin hunting.

Re: F70 users! My Brother Gave me A Homework Assignment
Posted by: NCtoad
Date: March 24, 2017 05:32PM
Quote
MarkCZ
First!
I spent an evening doing air test, in the house! and everybody knows that air test depth measurements DO NOT CARRY OVER TO REAL IN THE EARTH DEPTH!! and were not trying to say it does.
But! for silver coins there isn't anything about DIRT that would make the detector have greater depth than AIR!.

Next,
I want this thread to be more than just depth, I've already discovered some things about my F70 that I didn't know and that I didn't see in the manual. So, I'm hoping that some other F70 users will do some confirmation testing to see if these things carry over to ALL F70's.

I may have been able to run higher settings in an environment with less EMI, I did shut down my computers and cut the power to my WIFI.

Okay, here is one thing I found in my testing,
I used DE mode,
I used the 11" DD coil.
Test target was a US Silver Dime.
I started out with the sensitivity @ 25 and a -5 threshold and repeated the test by moving up the threshold step by step and recorded depth at each.
-5 = 2.5"
-4 = 3.0"
-3 = 3.25"
-2 = 3.5"
-1 = 4.0"
0 = 4.75
To this point all is well, but the next step sort of stumps me (well surprised me), take a look!
+1 = 7.0" (WoW, almost like boost)

There is a couple of things other than just the big jump at the +1 threshold! First thing is that up to that point the detector didn't have modulated audio!, but as soon as I reached that point it had a really SWEET modulated audio. Anybody else know about this? (or does your F70 do that?)


Mark
-
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.

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Re: F70 users! My Brother Gave me A Homework Assignment
Posted by: MarkCZ
Date: March 24, 2017 06:37PM
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) ?

Yes, I went through the threshold from -9, -5, -4, -3, -2, -1, 0, +1, +2, +3, +9,
at +2 the depth went to 9.0" at the 25 sensitivity, and stalled out at 9.0" for the rest of the trip.

I have a chart that's about ready to post but I'm going to confirm a few things before I do.

Also at each threshold setting I stepped up the sensitivity at, 25, 35, 45, 55, 65, 75, 80, 85, 95, and 99. (or until interference took over)

Also I did all the test in 3 tones.

Mark



Edited 2 time(s). Last edit at 03/24/2017 06:45PM by MarkCZ.

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Re: F70 users! My Brother Gave me A Homework Assignment
Posted by: MarkCZ
Date: March 24, 2017 07:24PM
Okay, here is something else that I didn't expect. (didn't know)
After I was done I picked out the max depth box which was 10" at a threshold of +2 and a 55 sensitivity. The idea was to go back to a known point and switch the detector over to SL mode (the known boost mode) and when I did NOTHING in the depth department happened:shrug: I still got the 10" but I didn't gain anything.
Now, something else did happen and this is something I want to confirm, but the modulated audio flipped to Non Modulated audio. So, I'm thinking non of this is in the manual either, I was still in the positive threshold range which had modulated audio in the DE mode!

The next thing I plan on doing is to go back to the chart and pick out certain points of interest and repeat with the same settings except in SL mode and see what depth gains I get or loose.

Mark



Edited 1 time(s). Last edit at 03/24/2017 07:28PM by MarkCZ.

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Re: F70 users! My Brother Gave me A Homework Assignment
Posted by: REVIER
Date: March 24, 2017 09:20PM
Also try DP and monotone with DE at least.
Your results could be different and maybe even better.



"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 1 time(s). Last edit at 03/24/2017 09:23PM by REVIER.

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Re: F70 users! My Brother Gave me A Homework Assignment
Posted by: dfmike
Date: March 25, 2017 10:21AM
I know the F5 has threshold control in disc. I wanted to know if the F70 is the only one to have it among the 13 kHz First Texas machines (T2, F70, F75).

Having threshold in disc is really practical at times.



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

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Re: F70 users! My Brother Gave me A Homework Assignment
Posted by: MarkCZ
Date: March 25, 2017 11:25AM
Okay, I'm back after some SL mode testing and what it looks like at this point is that the boost that SL mode does plays out around a zero threshold setting.

I used the unfinished chart for a base to compare to with the SL setting and here is what I got. Also, the inch numbers directly under the depth column is the depth
results from the SL mode, the gain numbers represent a gain difference from the DE mode.

Mode________________Threshold____________Sensitivity_____________Dept
SL____________________-9__________________25___________________3" = 1" gain
SL____________________-9__________________75___________________6.5" = 2" gain
SL____________________-4__________________95___________________9.5" = 2" gain
SL____________________-3__________________75___________________8" = 2.5" gain
SL____________________-1__________________75___________________10" = 2.5" gain
SL_____________________0__________________65___________________8" = .25" gain

If I'm looking at this right it looks like boost plays out at a threshold of 0 or above.

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Re: F70 users! My Brother Gave me A Homework Assignment
Posted by: MarkCZ
Date: March 25, 2017 09:14PM
Quote
REVIER
Also try DP and monotone with DE at least.
Your results could be different and maybe even better.

That's a good idea and what I can do is to just pick four or five key points on the chart and see if I can squeeze a little more out of the numbers.

Mark



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

WV62 - MarkCZ - Still Looking 52

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