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Gpx 4500 depth?
Posted by: kmyer74
Date: December 27, 2018 10:25AM
Hello everyone,i have a question about gpx depth. I use it for relic hunting. I have watched videos and guys have told me that they have dug .58 cal civil war bullets at 15+ inches. I have a test garden and a bullet at 12" i can barely here and i have another one buried at 14" and it can not be heard. I've also buried bullets at 13-15" in different soils but still couldnt them. I have tried adjusting the threshold,target volume and basically every setting. My brothers 4500 wont pick up the 14" bullet either but his settings are the same as mine. I even have a 14" coiltek DD coil and it still doesnt hit on the deeper bullet. I love my gpx and have had it a couple years but just wondering why im not hearing the deep bullets like others are. The soil i hunt in is moderate and only hot in a few places. I'm just wondering if anyone can see something in my settings that may be causing me to not hit the deep bullet. Any info will be greatly appreciated. My settings are:
Double D
Fixed
Special
Deep
Vol limit 12
GB general
Special- sensitive extra
Manual tune-auto
Motion-slow
Rx gain-13
Audio-deep
Audio tone-38
Stabilizer-8 to 10
Signal-10
Target volume-15

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Re: Gpx 4500 depth?
Posted by: Digger70pa
Date: December 28, 2018 09:09AM
I've never dug a bullet deeper than 12" with the 11" DD coil. Now I have with the 15" ultimate spiral coil. I've dug 14" bullets with that coil on my gpx4500. Try the sharp timing. I messed around with it yesterday & it made a deep target come through better. Good luck & HH



From The Great Appalachian Valley Minelab Fisher Teknetics Whites Garret detectors.

Re: Gpx 4500 depth?
Posted by: shep
Date: February 01, 2019 01:47PM
Although I hunt gold out west here, we are all looking for the best depth for our machines. I've had my 4500 since about a year after it came out. About 5 years ago, I sent it off to Woody @ detectormods.com in AU and he did his mods on it. It took abit to get it fine tuned but results are outstanding. Bill Southern of Nuggetshooter forum has modded 3000, Chip Brown has modded 5000 and my modded 4500 all will pick up a 1/2 gram lead 'nugget' at 16". A stock 5000 will not hear it and a 7000 will barely hear it scrubbing the ground. Might look into it.



Going to see the Elephant

Re: Gpx 4500 depth?
Posted by: Tony
Date: February 02, 2019 03:16AM
Quote
shep
Although I hunt gold out west here, we are all looking for the best depth for our machines. I've had my 4500 since about a year after it came out. About 5 years ago, I sent it off to Woody @ detectormods.com in AU and he did his mods on it. It took abit to get it fine tuned but results are outstanding. Bill Southern of Nuggetshooter forum has modded 3000, Chip Brown has modded 5000 and my modded 4500 all will pick up a 1/2 gram lead 'nugget' at 16". A stock 5000 will not hear it and a 7000 will barely hear it scrubbing the ground. Might look into it.

0.5g at 16"........show me personally and I will pay you 10K for your 4500.

Re: Gpx 4500 depth?
Posted by: shep
Date: February 02, 2019 11:53AM
Hate to take your money. Sounds like you don't believe it to be true. Might I suggest getting on Nuggetshooters.com forum and inquire about it. The owner of the site Bill Southern has a 3500 modded and can pick it up. Chip Brown of Prescott Valley has a 5000 modded and it'll pick up a 1/2 gram @ 16" also. So it isn't a fluke. You would think being this sensitive it would be noisy and unstable; not in the least and we hunt in very mineralized ground most of the time. You can check out the Woody's mod at detectormods.com.



Going to see the Elephant

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Re: Gpx 4500 depth?
Posted by: lytle78
Date: February 02, 2019 12:28PM
Not to get in the middle of this, but - what sort of shape and thickness are we talking about - and were these air tests?

Not asking out of doubt, just would like more info.



Rick Kempf

Re: Gpx 4500 depth?
Posted by: shep
Date: February 02, 2019 01:45PM
Well a friend of mine, Patrick (on the detecting forums) made up a tool. It’s a 18” long pipe with a pointed rod w/ nut welded on the end inserted in it. The pipe has inch marks scribed on it. We are usually out in the desert so ground is mineralized. We find an area at least 3-4’ clear of any targets (kind of hard sometimes). We drive this pipe/rod combo into the ground w/ a hand sledge hammer to whatever depth we want. Then we pull the rod out. Prior, I have taken a lead splitshot hammered down a little and then weigh on a digital gold scale. Cut down till it weighs ½ gram.
This is dropped down the pipe. Dirt is poured down pipe as pipe is pulled out and tamped down w/ rod. This sounds like it’s pretty elaborate but isn’t really. It’s the best way to have a known weight target at a known depth and in relatively undisturbed ground.
As said, a modded 3500,a modded 4500 and a modded 5000, all hear the target sweeping above the ground about an 1”-1 ½”. A stock 5000 w/ various coils and settings could not hear the target. Doc from Doc’s detecting out of Las Vegas (a well known gold detectorist) could barely hear target scrubbing the ground with his 7000. There were several other witnesses and we’ve repeated test at several get togethers.



Going to see the Elephant

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Re: Gpx 4500 depth?
Posted by: lytle78
Date: February 02, 2019 05:17PM
Thanks for the detailed description - sounds like a valid test. I would still appreciate the diameter and thickness.



Rick Kempf

Re: Gpx 4500 depth?
Posted by: shep
Date: February 02, 2019 05:29PM
3/16"-1/4" round, thickness? small 1/8" split shot flattened and cut to weight



Going to see the Elephant

Re: Gpx 4500 depth?
Posted by: Tony
Date: February 02, 2019 07:13PM
My stock 4500 (which I know like the back of my hand) will find a similar target at about half that depth in heavy ground.
I have access to many modded Minelab machines down here so I will test.................many of the pro's run stock machines which leaves me wondering why?

Your test sounds valid but a better test is to mark out 3 or 4 areas with only one area containing the "target" and the others devoid of any targets. Be prepared for a lot of digging and cursing with no target retrieval. Even better.....mark out 3 or 4 areas (with no buried targets !) and ask an operator to find the target. It's a real eye opener.

Many false/ground noise targets will be dug.....and still no metal test target located. Blind test the only way to go.



Edited 1 time(s). Last edit at 02/02/2019 07:16PM by Tony.

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Re: Gpx 4500 depth?
Posted by: lytle78
Date: February 02, 2019 09:45PM
OK, good, now Measure the thickness, data/science remember



Rick Kempf

Re: Gpx 4500 depth?
Posted by: shep
Date: February 02, 2019 09:46PM
One could do the blind test, but think that would be more of a test of the operators,but might try it at next outing. All this test does is show whether a detector can hear a known target at a known depth using a normal natural swing at a natural swing height. Scrubbing the ground isn't really practical. When there is a distinct digable signal on the speakers with several modded detectors and other detectors can't hear it at all. This tells me a lot!
As for why the 'pro's' stick with the stock detectors; here in the states, Minelab has made it known they will not work on a modded detector through their dealers. Some issues that may be true, but on my last trip out my function switch was failing. When I got home, I found a Minelab repair center on the east coast, that said no problem. In fact, the repair and turn around was faster than any prior repair done by Minelab in LV or Chicago and cost very reasonable.
A side note, 5-6 years ago, my 4500 was real erratic. Sent in to Minelab, Las Vegas and Chicago, 3 times; still wasn't right. I contacted Woody in AU, he fixed it and put one of his earlier mods on at a fair price. On some of the AU forums, some don't care for Woody. Don't care, he knows his electronics .He has a 5 year warranty to boot.



Going to see the Elephant

Re: Gpx 4500 depth?
Posted by: shep
Date: February 02, 2019 09:52PM
Dark and cold out. Just for you. tomorrow I will make up some new targets for next outing and measure for you, okay? ;-)



Going to see the Elephant

Re: Gpx 4500 depth?
Posted by: shep
Date: February 02, 2019 09:57PM
Excuse my ignorance, but I've never heard of a 15" Ultimate spiral coil. Who makes it? My favorite is the Nugget Finder 12" EVO round mono.



Going to see the Elephant

Re: Gpx 4500 depth?
Posted by: Tony
Date: February 03, 2019 12:20AM
Quote
shep
Excuse my ignorance, but I've never heard of a 15" Ultimate spiral coil. Who makes it? My favorite is the Nugget Finder 12" EVO round mono.

Made by Detech....DD coil....very heavy......deep seeking especially in NORMAL timings.
I have the 12.5DD by Detech...much lighter and as deep as the bigger 15".

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