F70 coil air test

[Mr. Beard]

Did an air test on 3 coils for the F70 and a F5 stock coil. The F70 coils tested were the 6.5X3.5 sniper, the 11DD stock, a NEL 12.5X8.5 and a F5 10concentric.
Air tested a cent, a nickel, a dime and a quarter for the ID numbers and depth test.
The F70 settings were Sens at 80, Disc at 15,and Threshold at -3.
Coils were tested on each coin multiple passes in front of the coil for the target ID number and then for depth on a good solid tone before the tone became choppy.

Due to the detector being in a room with lots of electrical, this was just a base test and results will be a bit different for each individual detector and outside ground conditions.

The sniper coil depth was 5 to 5-1/2 inches.
The 11DD coil depth was 7 to 7-1/2 inches.
The Nel Hunter 12-1/2X8-1/2 depth was 8 to 8-1/2 inches.
The F5 10 concentric coil was 5-1/2 to 6-1/4 inches.

 

[REVIER]

Did an air test on 3 coils for the F70 and a F5 stock coil. The F70 coils tested were the 6.5X3.5 sniper, the 11DD stock, a NEL 12.5X8.5 and a F5 10concentric.
Air tested a cent, a nickel, a dime and a quarter for the ID numbers and depth test.
The F70 settings were Sens at 80, Disc at 15,and Threshold at -3.
Coils were tested on each coin multiple passes in front of the coil for the target ID number and then for depth on a good solid tone before the tone became choppy.

Due to the detector being in a room with lots of electrical, this was just a base test and results will be a bit different for each individual detector and outside ground conditions.

The sniper coil depth was 5 to 5-1/2 inches.
The 11DD coil depth was 7 to 7-1/2 inches.
The Nel Hunter 12-1/2X8-1/2 depth was 8 to 8-1/2 inches.
The F5 10 concentric coil was 5-1/2 to 6-1/4 inches.

Nice way to kill time...but it doesn't mean a whole lot.
Maybe a slight idea on depth differences between the three DD coils...maybe, but even then your results are so skewed compared to real world results I have seen with similar coils I don't know if I would trust any of it.
I have done a little testing inside with a few coils on my F70 too, I got better results on every one so what is exactly happening in your home that is suppressing that thing so much I have no idea.

Also that F5 concentric coil, different frequency than the F70 version, I have the correct one and it works way better.

Real world depths with my coils....

In great soil

5" Fisher sniper....7-8" easily, confidence to hit 10" consistently and I have seen 12-14" pop up on the screen here and there also.
Most never got dug because I don't like digging that deep in public parks but these were real signals

11" DD... Got down to 15" on one target with great repeatable tones and numbers.
Excels at shallow areas but lives more at the 6-12" range.
From what I can tell it seems pretty efficient all along that range and ID's and tones on better, deeper targets in the double digits is no fluke.

10 Elliptical concentric... I dug good targets from 8-10" I went after several 10" beaver tail tabs that sound high like a dime when they are that deep for some reason.


Depth in bad soil here in the SE...

Here we are loaded with mineralized soil both red and black.
My hunting areas in the city proper and even sites nowhere near the city can be and usually are also infested with scary amounts of actual iron garbage.
Here, most anything we find past 5-6" is usually luck and that is in both public areas like parks and private areas like lawns.
I have managed to exceed that a little by thinking outside the box in my settings and by observing some strange but repeatable behavior.


5" Fisher coil. ..I found my deepest V nickel with that thing despite bad conditions at 8" ...might have been closed to 9".

11" DD. ..I also have dug good targets up to that 8-9" level and many last that 5" barrier.

10" Concentric. ...about 7-8" on a great target , a silver Masonic coin.


Then I added a larger 14" or so Cors Cannon coil since I moved back to the south.
Not tons of use with that one because the snipers are my go-to coils but still, with limited use, I found this thing could probably get pretty deep...meet or probably beat that Fisher 11" DD, anyway.oh

Also I added a Nel Sharpshooter coil.
In airtests it almost matches the 11" DD in double digit numbers, in the real world in the garbage I hunt in 6 -7-8" is not unusual.
I hit a nickel at 10" in less challenging sandy soil and plenty last our 5" barrier.

Not to mention those depth results could be affected by changing your settings, also.


Suggests have their place but in your case you're seem pretty low.

 

[Mr. Beard]

I know the depth will be much different in "the real world" as you say, but I was mostly interested in the target ID numbers and the depth reading on the screen compared to a ruler. The depth onscreen matches the ruler, even on the mismatched frequency coil.
You say "Suggests have their place but in your case you're seem pretty low."........I know they are very low in the depth results.........and I stated this was a base test, and also was done in a room with a lot of electronic equipment (stereo, computer setup, dual 4 ft. ceiling flourescent light fixtures) and the detector was NOT set to optimum settings.

 

[REVIER]

I know the depth will be much different in "the real world" as you say, but I was mostly interested in the target ID numbers and the depth reading on the screen compared to a ruler. The depth onscreen matches the ruler, even on the mismatched frequency coil.

Yea, in the "real world" one small piece of metal or some hotter mineralized soil can skew both those ID numbers and throw off those depth readings too...big time.
Whatever, you decided to take the time to do these tests so I hope you found out what you needed to.

 

[WV62]

Air testing is equipment not what it will do in the ground. It gives a base line as to what the equipment will do.

Not so long ago I bought a Goldbug 5" coil for my F5 and I just knew it was going to be the greatest thing since sliced bread. I bought it new from a dealer and I questioned them about being compatible with the F5 and they assured me that it was. So without any testing I took it hunting and messed with it for a while and then changed to another coil. When I got home I air tested it and the best it would do is 3" on a dime. So I wasted a couple of hours of my real world hunting and made a new coil used. If I would have air tested first I would have sent the coil back.

Sorry, but I think for some there is still a need for air testing.

Ron WV

 

[MarkCZ]

Also, air is the only universal media that people around the world have in common, that puts real world results good or bad
in your part of the world and not mine, earth here, earth there if very hard to compare.
And to note!
There is anything about dirt that increases the depth of a metal detector, not is there anything in air to restrict the depth range.
I've air tested many detectors and coils sense 1981 and except for Iron halo I've NEVER had a single one exceed the air test depth
in the field.
Now that being said, real world results cannot be fairly compared to air test TRUE!
So, for me if I get an 11" max air test on a silver dime, I'd be foolish to expect more than that in the field.
I acquired a detector a few years ago and on their forum's they claimed dimes @ 10" easy (in the field, in average soil) so, when I air tested it
5" was MAX!! so in the field with just a couple inches of grass all it would do was 3" to 4" in the dirt. Well, I didn't keep it more than a week, the
whole point in buying it was I needed a detector that would reach around the 7" to 9" range for park hunting.
Never! have I found a coin in the ground deeper than the detector will air test! never.
In fact an 11" air test is iffy at best to make 9" in the dirt, 12" to 14" air test might come close to 10" to 11" and even less in bad soil.
So, on one side of the coin air test are worthless and they do not compare to actual field results, but on the other side of the coin air test is way to
see the likely max depth ability of a detector/coil combination to detect nonferrous targets (coins) What effect earth (dirt) has to a detector is like driving
a car at night in the fog, the better the soil the less the fog, the worse the soil the more the fog, where as air test is driving in the daylight with no fog!!!
Nothing about FOG (minerals) that give more depth to a detector.

 

[still looking 52]

Air testing is not meant to replace Real world testing it's meant to add to real world testing. Added knowledge is added finds plus for some people air testing is fun and adds to their joy for this hobby.

 

[REVIER]

I am not saying there is no place in the world for air testing, I have done it myself, I am a big fan of WV's charts and know full well of its benefits and I appreciate the time and effort people spend to do this and report back on the forums including this one.
What I am wondering is the results reported were so throttled and could be so different than a lot of the same targets would be in the real world especially at the scanning depth limit that was tested for, (not just the depth but all components of that "tone"), that I don't know exactly how much help this info would be.

I never saw a mention of what tones were used in this test...multi, one tone, DP...
The sounds of the tones, sure, they could be the same indoors and out but they could also be skewed a bit due to that throttling.
The depth for sure seems way off to me knowing what I have seen outdoors and even in my own testing indoors.
I was just concerned the OP might consider the results something you could trust and hang your hat on all the time, and I do realize he knows his results are throttled due to the EMI.

So testing is fun for some and writing down results and correlating everything can be also and can also be baseline useful....I get it.
In this case, FOR ME, I am not seeing a whole lot of really super helpful information I can use from this particular set of tests...but again, that is me.
You didn't test for me so don't worry about it.
If you had the time to do the tests, enjoyed doing them and got something positive or learned something from the results that is all that matters.

 

[MarkCZ]

I can't think of everything I've discovered air testing that I may not have every discovered otherwise, but here is a couple.
(1)-On several detector models in the past during air test I found that testing nickels out past the 5" point that they would high tone,
And many people in the day couldn't explain why they would fine deep nickels when their disc was set to discriminate them out!
(2)-Air testing a silver dollar to find your detector wouldn't hit on it at all, unless you were in all metal mode, just think of this for a minute,
a person hunts for 6 or 7 years and on his or hers bucket list is a Silver Dollar and never knew that detector would have hit on one with it
laying on top of the ground.
(3)-My F70 has modulated audio, but not at certain sensitivity and threshold settings, that's not in the manual!
(4)-Doing air test I've found the point when a rusty screw and a coin is passed in front of the coil at the same time how much spread is needed
for a clear tone, and to that was the fact that if the coin passed first the detector would hit on the coin, but it wouldn't when the screw passed first,
that is to say it would only hit in one direction of the pass and null out the other way!
(5)-I've had detectors that in coin air test no matter the settings that the max depth was 4" and being a coin hunter and knowing that most of the older
silver coins in my area run 5" to 8" deep, that it would be a total waste of time to even take the detector out for a hunt!
(6)-Air testing the F70 I found that the SL speed that many people like to call the Boost Mode, expires at threshold settings 0 and above, No BOOST!
see the above chart!
(7)-Same chart, check out the modulated audio!
(-I believe one air test my brother Ron did with some detector was with a 5-pound bag of US silver coins and if I remember right the detector passed
right over it! (we topically do NOT hunt in all metal)
(9)-I'll not mention that during in house testing you can learn what the different sources of EMI are and how they effect the detector. Power it on, make some
search settings and move close to a florescent light fixture, a computer monitor, microwave oven, cellphone. Can you find a room with a fair amount of EMI
and mange the detector setting to get it stable enough to possibly operate?, okay, I will mention it!


The point in all this is that they're things that can be learned about a detector doing valid air test! but there is WAY more to be learned in actual field use.
I mean I haven't done any air test with my F70 in a couple of years, nor have I used my test garden in even a longer period time, neither is of any use
to me anymore, but, if I get another detector then it starts allover again.
All those years, of all those people finding deep nickels, and all their worthless reason to explain it on countless forums, AND nobody EVER air tested to see if a nickel would
high tone at some point out from coil, LoL!!
They halo, LoL! because as soon as I took it out of the hole and laid in on the ground the detector null-ed out over it, Nope! they NEVER raised the coil
while it was on the ground to hear if it high toned at the depth it was in the ground, LoL! and these people were EXPERTS!!!!!


MarkCZ

 

[GroundScanner]

Something to think about. Good write up. GS

I can't think of everything I've discovered air testing that I may not have every discovered otherwise, but here is a couple.
(1)-On several detector models in the past during air test I found that testing nickels out past the 5" point that they would high tone,
And many people in the day couldn't explain why they would fine deep nickels when their disc was set to discriminate them out!
(2)-Air testing a silver dollar to find your detector wouldn't hit on it at all, unless you were in all metal mode, just think of this for a minute,
a person hunts for 6 or 7 years and on his or hers bucket list is a Silver Dollar and never knew that detector would have hit on one with it
laying on top of the ground.
(3)-My F70 has modulated audio, but not at certain sensitivity and threshold settings, that's not in the manual!
(4)-Doing air test I've found the point when a rusty screw and a coin is passed in front of the coil at the same time how much spread is needed
for a clear tone, and to that was the fact that if the coin passed first the detector would hit on the coin, but it wouldn't when the screw passed first,
that is to say it would only hit in one direction of the pass and null out the other way!
(5)-I've had detectors that in coin air test no matter the settings that the max depth was 4" and being a coin hunter and knowing that most of the older
silver coins in my area run 5" to 8" deep, that it would be a total waste of time to even take the detector out for a hunt!
(6)-Air testing the F70 I found that the SL speed that many people like to call the Boost Mode, expires at threshold settings 0 and above, No BOOST!
see the above chart!
(7)-Same chart, check out the modulated audio!
(-I believe one air test my brother Ron did with some detector was with a 5-pound bag of US silver coins and if I remember right the detector passed
right over it! (we topically do NOT hunt in all metal)
(9)-I'll not mention that during in house testing you can learn what the different sources of EMI are and how they effect the detector. Power it on, make some
search settings and move close to a florescent light fixture, a computer monitor, microwave oven, cellphone. Can you find a room with a fair amount of EMI
and mange the detector setting to get it stable enough to possibly operate?, okay, I will mention it!


The point in all this is that they're things that can be learned about a detector doing valid air test! but there is WAY more to be learned in actual field use.
I mean I haven't done any air test with my F70 in a couple of years, nor have I used my test garden in even a longer period time, neither is of any use
to me anymore, but, if I get another detector then it starts allover again.
All those years, of all those people finding deep nickels, and all their worthless reason to explain it on countless forums, AND nobody EVER air tested to see if a nickel would
high tone at some point out from coil, LoL!!
They halo, LoL! because as soon as I took it out of the hole and laid in on the ground the detector null-ed out over it, Nope! they NEVER raised the coil
while it was on the ground to hear if it high toned at the depth it was in the ground, LoL! and these people were EXPERTS!!!!!


MarkCZ

 

[MarkCZ]

Something to think about. Good write up. GS

Thanks, but after looking at it and reading it again today I thought I would re-post it in better form just to make it read better.

I can't think of everything I've discovered air testing that I may not have every discovered otherwise, but here are some of them.

1- On several detector models in the past during air test I found that testing nickels out past the 5" point that they would high tone,
And many people in the day couldn't explain why they would fine deep nickels when their disc was set to discriminate them out!

2- Air testing a silver dollar to find your detector wouldn't hit on it at all, unless you were in all metal mode, just think of this for a minute,
a person hunts for 6 or 7 years with the same detector and on his or hers bucket list is a Silver Dollar and they never knew that the
detector wouldn't have hit on one with it laying on top of the ground.

3- My F70 has modulated audio, but not at certain sensitivity and threshold settings, that's not in the manual!

4- Doing air test I've found the point when a rusty screw and a coin is passed in front of the coil at the same time how much spread is needed
for a clear tone on the coin, and to that was the fact that if the coin passed first the detector would hit on the coin, but it wouldn't when the screw passed first,
that is to say it would only hit in one direction of the pass and null out the other way. How many people pass on digs that only hit in one direction?

5- I've had detectors that in doing coin air test no matter the settings that the max depth was 4" and being a coin hunter and knowing that most of the older
silver coins in my area run 5" to 8" deep, that it would be a total waste of time to even take the detector out for a hunt!

6- Air testing the F70 I found that the SL speed that many people like to call the Boost Mode, expires at threshold setting of 0 and above, No BOOST!
see the above chart!

7- Same chart, check out the modulated audio!

8- I believe one air test my brother Ron did with some detector was with a 5-pound bag of US silver coins and if I remember right the detector passed
right over it! (we topically do NOT hunt in all metal)

9- I'll not mention that during in house testing you can learn what the different sources of EMI are and how they effect the detector. Power it on, make some
search settings and move close to a florescent light fixture, a computer monitor, microwave oven, cellphone. Can you find a room with a fair amount of EMI
and mange the detector settings to get it stable enough to possibly operate?, your likely going to need to be able to that in some real world hunting.
Okay, I will mention it!


The point in all this is that they're things that can be learned about a detector doing valid air test! but there is WAY more to be learned in actual field use.
I mean I haven't done any air test with my F70 in a couple of years, nor have I used my test garden in even a longer period time, neither is of any use
to me anymore, but, if I get another detector then it starts allover again.

All those years, of all those people finding deep nickels, and all their worthless reason to explain it on countless forums, AND nobody EVER air tested to see if a nickel would
high tone at some point out from coil, LoL!!
They halo, LoL! because as soon as I took it out of the hole and laid it on the ground the detector null-ed out over it, Nope! they NEVER raised the coil
while it was laying on the ground to hear if it high toned at the depth it was in the ground, LoL! and these people were EXPERTS!!!!! If you knew your detector was doing this
just think at how you might manage it (plan to use) in the field.

MarkCZ

 

[Druid]

Excellent post Mark.
Thanks for the time & effort.
Cheers,
Drew.