f75 discrimination be aware.

So I was testing VDI numbers on the f75. I had nickels notched in and iron, foil, and tabs disc'ed out. I tried an indian head penny:VDI 55. I tried a V nickel:VDI 27. Perfect I thought. Then I put them both together and...nothing. The combo of the penny and the nickel was silent(disc'ed out). Removing the discrimination, the combo read a VDI of 42.(Tabs section.) in this case, the nickel brought the VDI of the indian head penny down into the pull tab section. Down averaging, another form of masking. Just be aware that pocket spills with low and mid conductors can be disc'ed out.

Bey.

That's why I never notch anything, and try to run 0 disc whenever possible. I want to be able to make the dig/no dig call, not the machine. I found a nice coin spill earlier this year full of indians, wheaties, v nickels, buffalo nickels, a merc, and a morgan dollar (the merc and morgan were spread a few feet from the main spill), but I bet the F75 would've missed the main spill with the notch setting.

Good point.

Discrimination is the root of all evil.

Beyonder-Pa Wrote:
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> So I was testing VDI numbers on the f75. I had
> nickels notched in and iron, foil, and tabs
> disc'ed out. I tried an indian head penny:VDI 55.
> I tried a V nickel:VDI 27. Perfect I thought. Then
> I put them both together and...nothing. The combo
> of the penny and the nickel was silent(disc'ed
> out). Removing the discrimination, the combo read
> a VDI of 42.(Tabs section.) in this case, the
> nickel brought the VDI of the indian head penny
> down into the pull tab section. Down averaging,
> another form of masking. Just be aware that pocket
> spills with low and mid conductors can be disc'ed
> out.
>
> Bey.

So combining the higher conductor and the lower conduct, the detector reported in the middle. So it worked as advertised from a notch standpoint. I think instead of the notch being the point, it should be in fact VDI numbers don't tell the whole story per individual coin wise when mixing different levels of conductors. Granted mixing all high conductors actually helps but a little story. I hunted a site twice with an etrac. Both times I came on this target, read very good high conductor with the screaming tone the minelabs are known for. I could lift my coil off the ground almost 12" and still get the signal. So I thought "can" all the way on both hunts. Well I hunted the site a 3 time with the etrac. Finds were almost nonexistent understandly so and I came back on this same signal. Again with coil what seemed like a mile in the air , a good high tone signal. So I then put the coil on the ground and swept in as close as I could before getting any tone whatsover. I discovered the target wasn't can sized. I dug the target and it turned out to be 1 IH and 2 wheats stacked like in a coin roll at 7 inches deep, thus providing the ultra strong signal even the coil extended way in the air over them. Some kids at the old house must have buried them in the coin roll orientation years ago. So watch out. just lifting the coil may not tell the whole story about what's under your coil!!!!



Edited 1 time(s). Last edit at 03/28/2015 12:39AM by tnsharpshooter.

Aren't almost all coin spills going to be average readings by nature?
Aren't all mingled targets average as well?
Too much emphasis on VDI numbers and not enough on tones.
Tones which do not match VDI numbers are "must diggers"
The etrac is easy , the F75 in Dp is not so.

"Aren't almost all coin spills going to be average readings by nature?
Aren't all mingled targets average as well?
Too much emphasis on VDI numbers and not enough on tones.
Tones which do not match VDI numbers are "must diggers"
The etrac is easy , the F75 in Dp is not so. "

True, but thats not what this post is about. This is for those that DO use VDI and DO use notch. Tone wasn't discussed here as the point was VDI and NOTCH USAGE can cause you to miss targets. There are some new people that are unaware of these types of scenarios, so it was for their benefit. I was using 1N for tone.

Bey



Edited 1 time(s). Last edit at 03/28/2015 02:47AM by Beyonder-Pa.

Ive never used notch in my life. Is that something jewerly hunters mainly use?

deathray Wrote:
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> Ive never used notch in my life. Is that something
> jewerly hunters mainly use?


Not me.
I have found gold rings from 24 on up using my Fishers.
A thin gold chain came in at iron.
Silver rings are from zinc to higher and into dimes and quarters.
Silver chains are weird and I have dug them from foil on up to zinc.
The most I ever knocked out on my F2 was iron, the F70 has the notch feature but I never use it and my disc on that one is usually down to iron but never higher than 23.
On my Tesoros the disc knob rarely even gets up to the F in foil.

I find a lot of silver and gold jewelry.