Digging Minus VDI

[ORDOVIC]

While out detecting today with my MXT on pasture I dug up two deep signals and showed up on the VDI scale as minus readings between -12+0.At first I thought they where Coke signals but when I pin pointed them I got a very faint narrow signal rather than a wide one like you get if coke is near the surface so I decided to dig them and to my surprise one was a Victorian penny which was around 7-8" down  and the other was a Musket ball from about the same depth.

Has anyone else experienced the same situation ?


ORDOVIC

[Tafflaff (Rob)]

My programme on the DFX allows down to -25 as a good signal though I dont dig under  5 , everytime I've have its been ultra thin foil or iron.  Pick a day on a quietish field - one you've done to death  and dig every signal whilst noting the numbers . Gives you a good idea on how accurate the machine can be.

[rjm]

This is common with a lot of machines.

On my Minelab I only used to dig positive numbers until I read a post and then accepted some negative with a good tone to them. They turned out to be coins that had some crud or rust on them.

By accepting some negative VDI you are more likely to locate a target near iron than if you were accepting all positive VDI's.

On my V3 coke usually comes in with a buzzy sound and a VDI of 3, and normally the coke is an inch or so below the surface.

I normally only accept positive VDI's unless the field is quiet then I open up and accept some negative VDI's.

It's a case of knowing your machine and how quiet or noisy you want the audio!