Low conductors reading high--why?

[Calnevaroy]

I'm using my V3i outfitted with the 5.3 coil and having aluminum read rather high, in the 60's, 70's and 80's. I have the Rx Gain at 12 and Discriminate at 90. I'm using the 5Hz High Pass filter in Best Data. The Ground Probe VDI reads 93 and is fairly consistent where I live in the Sacramento valley. Also, I have my Autotrac locked with the offset at +1. I tried changing just about everything up and down including varying my sweep speed to no avail. One thing I noticed too was a 1906 V nickel at 8" read quite high as well. All low conductor hits reading high show as 22.5Khz as the predominant frequency in the pinpoint all metal mode. Am I doing something wrong or is this characteristic normal for the V3i?

 

[yazoo]

Detune it a bit looks like you are way hot. Try a gain of about 6 and disc at about 84-86 then bump a lil at a time to make it hotter or go the other way. G.L.
Yazoo

 

[Larry (IL)]

The VDI is derived from conductivity AND mass. A small piece of a low conductor will read low and a large piece will read high. Pop cans usually read as a quarter while the tab reads as a nickel, both are aluminum. It sounds like everything you are doing is right on especially if the high VDI's read 22.5 dominate for low conductors, a dead give-a-way it is a trash target.

What is a high VDI for a deep Nickel? Most deep target ID's are influenced by many factors and I consider them not reliable. As long as your detector is running stable, you are doing good.

 

[Calnevaroy]

The VDI is derived from conductivity AND mass. A small piece of a low conductor will read low and a large piece will read high. Pop cans usually read as a quarter while the tab reads as a nickel, both are aluminum. It sounds like everything you are doing is right on especially if the high VDI's read 22.5 dominate for low conductors, a dead give-a-way it is a trash target.

What is a high VDI for a deep Nickel? Most deep target ID's are influenced by many factors and I consider them not reliable. As long as your detector is running stable, you are doing good.

Thanks Larry and Yazoo. As with the small and deep target of the V nickel I find that even small and common pieces of aluminum (square tab) not buried very deep (3"- 6") still respond with high tones. I tried backing off on the Rx and Discriminate sensitivity and changed my filters up to 10Hz but never found much difference in ID. I suppose I'll have to check every suspicious high tone in the pinpoint mode for better ID'ing. Thanks for the input, it's appreciated!

 

[Rob (IL)]

Sorry but this doesn't sound normal. How are you ground balancing? What is detector doing during G/B?
Do a ground probe and list the readings. My ground sucks and doesn't do this.

 

[jalon]

Is there any chance that you're searching in a single freq. mode and have the "normalizer" un checked? I guess it's possible to go into a 3 freq pinpoint mode and back to a single freq. search mode. I never did try that, but non-normalized will make low cons read higher. Just a wild guess though.
John london

 

[Rob (IL)]

it's possible to go into a 3 freq pinpoint mode and back to a single freq. search mode

I wish, but it won't work.

 

[cypearl]

It depends how big is the foil you are testing with. if it is a ''big peice'' it is normal to be a high vdi. I found pieces of foil that reads 50 and 63 vdis and -3 to 11 for example. The other thing now two targets together no matter their conductivity shows a higher vdi number if they are put together than individual.