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Discrimination with the GPX 4500
Posted by: cookie58
Date: February 15, 2018 03:51PM
Somebody that is an experienced user of the 4500------Can you tell me if there is any discrimination with this machine with relics. If so, is it only with hearing or is there a setting that causes this machine to null (if it really does) over ferrous materials? I have heard a little about the timing, but not a whole lot to really understand. I had a TDI earlier which seemed to have no discrimination at all. How does the 4500 compare? Information on anything is always appreciated. Thanks.........

Re: Discrimination with the GPX 4500
Posted by: anbenson
Date: February 16, 2018 09:21AM
The 4500 has iron reject with the use of DD coils. With the standard 11 inch coil, iron reject works down to about 6 inches. larger coils the reject goes a little deeper. Iron reject doesn't work with mono or anti-interference coils. I also have the TDI which you can discriminate to some degree, but the GPX is far better than the TDI when discriminating iron. On the GPX when you're using iron reject the signal will either null completely or breakup when going over an iron target. Remember it only works to a certain depth, but so does the discrimination on VLF machines, as far as that goes. There are other characteristics that iron gives at depth but for the most part you'll have to use the machine and learn those on your own, too hard to explain. Good deep targets just sound good, iron not so much.

Re: Discrimination with the GPX 4500
Posted by: cookie58
Date: February 16, 2018 02:07PM
Anbenson, thanks. Maybe, I will be learning more later on. I hope that I do not annoy anyone for asking questions......Thanks....

Re: Discrimination with the GPX 4500
Posted by: anbenson
Date: February 16, 2018 03:56PM
Not a problem. We're all here to learn, ask all the questions you want.

Re: Discrimination with the GPX 4500
Posted by: jimmie
Date: February 17, 2018 09:56PM
I use mine for relic hunting and I run iron reject on 6 and when I hear a good tone I go in a circle around it and usually if it nulls while checking this way it is iron. Another way is to approach the target and when you get a good tone on the front of the coil go past the target and check the heel of the coil coming back, it should sound good coming back. Then step around 90 degrees and do the same and if it sounds good dig it.

Re: Discrimination with the GPX 4500
Posted by: cookie58
Date: February 18, 2018 01:02PM
Thanks Jimmie. What about high tones? Are they always iron, or only if they null? Tell me about a button sound......Thanks.

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