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Bruce Candy Technical Paper - GPZ 7000 Zero Voltage Transmission (ZVT) Explained


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The paper suggests that using a side to side motion while walking forward is the best way to get an average of a large volume of ground when initially doing the ground balance. It is then adding that doing an additional update to the ground balance by pumping the coil up and down over a single ground balance is acceptable. Not necessarily preferable. Pumping up and down over the ground not to be confused with moving the coil forward and back, heel to toe. I avoid heel to toe motion of a coil under nearly all circumstances personally. Most coils are designed to be swung side to side so it is a good habit to avoid. I do use the tip of an elongated coil as a pinpointing device in a hole but that is not the same thing.

Never, never ground balance over targets.

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 I might have discovered something useful this weekend. There are globs (Technical geologic term) of hot ground where I was detecting that are easily confused with a very deep large target, even after digging several inches. Also the roots of large trees give a signal that tend to make you start digging and wasting time. A few passes over the these with a forward-back motion greatly reduces or eliminates these signals. I experimented with this enough to be confident that good targets are not being balanced out. I'll go dig up a few multi-ounce nuggets next time I'm out just to be sure.

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Right, I wasn't suggesting to balance over a target.

 

Seperately, I was assuming since I haven't read anything to the contrary from Minelab, that is ok to move the coil up and down over a target or another way of saying in and out of the dig hole (while not quicktracking) without worry of balancing the target out and without having to dig a crater size hole that allows a side to side sweeping motion.

 

I only mention it because it seems I've read in a few different places now people saying not to do that or you could potentially make good targets disappear and that it is a bad habit, which has been somewhat contrary to my experience digging but I haven't swung the Z nearly as much as some of you guys.

 

I've noticed that sometimes swinging forward to back is more sensitive on tiny targets than side to side regardless of their orientation or geometry, at least so far in my limited sample base. When I'm crumbing GB2 territory I sure seem to pick up a lot more doing that at least maybe it's just psychological at this point not sure. I've used almost exclusively mono coils up until now so still getting the hang of this DOD.

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Have not tried heel to toe for targets..... thanks.

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Ho, ho, you got me there Dave. In automatic tracking since it is always ground balancing it is inevitable you will be ground balancing over a target. And I did just say never do that!

It may very well prove that a person in some places where the ground mineralization does not vary much that you should run the GPZ in fixed. I always ran my GPX in fixed, and every VLF I use normally the automatic ground tracking stays switched off.

JP says there is concern that the GPZ tracking can balance out faint targets and that he has made the programmable "User" button the ground balance setting, just do he can temporarily turn the ground tracking off. That seems to argue to me that I much of the ground I detect in, that maybe just leaving the tracking off is a better idea?

I honestly do not know for sure. I admit some things when I get a new detector, I just go with a bit on faith. It appears to me that extreme care has gone into making the GPZ ground tracking very sophisticated and reliable. I immediately just started using it constantly and so far have not had any reason at all to regret doing so. Maybe with more use and more consistent attention on my part I will decide otherwise. I got a pretty good start at getting good with the GPZ but everything pretty much came to a halt in December and I have minimal time using it the last three months.

Now, I will be using it nearly every day in the very near future. Hopefully I can complete my journey of learning most everything there is to know about the GPZ 7000. I am certain things I am doing now or believe to be true may be modified or even reversed with more use. That is part if the fun, having an open mind and learning new things. Right now I am pretty darn excited. I am going to go find a bunch of gold this summer!

I am letting the GPZ tell me how it likes to be used instead of trying to tell it how I want it to work. So far that has been working real well for me.

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I had just dug up a specie last week that went 85 g with 4.5 grams of gold in it and one of the other guys came over for a look. the interference started coming through so I did an autotune to let him in closer and was just re doing the ground balance procedure when a definite signal came through. how it came through with the coil doing that speed is beyond me but after I completed the balance I went back to where the signal came from and out came a very small steel sliver off a dozer blade. that area had produced a specimen that went 20 oz with about 4 oz of gold from 16" in enhanced with the 5000. the smaller specie and the steel were within 10 feet of the original find and I have no doubt I had covered the area numerous times with the 5000 trying to find the big boys father.

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Good on ya, Tricky; the Zed's continuous wave simply lights up the gold that pulse induction cannot, making finds like yours on thrashed patches possible. I got some shallow dinks the other day with my Zed that even the SDC 2300 couldn't see. Happy bipping...

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 I might have discovered something useful this weekend. There are globs (Technical geologic term) of hot ground where I was detecting that are easily confused with a very deep large target, even after digging several inches. Also the roots of large trees give a signal that tend to make you start digging and wasting time. A few passes over the these with a forward-back motion greatly reduces or eliminates these signals. I experimented with this enough to be confident that good targets are not being balanced out. I'll go dig up a few multi-ounce nuggets next time I'm out just to be sure.

Klunker you have "discovered" a good technique, tree roots only signal as the windings are exposed gradually through a side to side motion, I'm pretty certain it is caused by one winding being over or near the root and the other not being over the root, and the coil is reacting to the wet sappy section of the plant (they draw up mineralised water in the gold fields, and therefore are conductive). By approaching with the front of the coil in a push fashion you have exposed both tips of the receive windings to the target and learned it is most likely not a good target.

 

Be careful however because if it is a deep large nugget then the middle of the coil needs to be exposed to get a good response, the Super D coil has to be right over the top of a target to get the best depth possible, it is NOT like a Monoloop coil in that respect. However both windings will respond to a deep target when swept from left to right, whereas the tree root will only be reacting to first approaching  winding not both.

 

JP

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Qld Sandy, between reading your post about the GPZ having more like a computer doing the ground balancing and looking at that beautiful car in your avatar got my wheels turning. 

 

Hi Russ,

If you like my Chevy (actually a Fisher body US version) you'll probably like the T-Bucket I'm building when I have the time.

Cheers.

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  • 2 years later...
On 3/27/2015 at 1:37 AM, Steve Herschbach said:

 

Now, I will be using it nearly every day in the very near future. Hopefully I can complete my journey of learning most everything there is to know about the GPZ 7000. I am certain things I am doing now or believe to be true may be modified or even reversed with more use. That is part if the fun, having an open mind and learning new things. Right now I am pretty darn excited. I am going to go find a bunch of gold this summer!

I am letting the GPZ tell me how it likes to be used instead of trying to tell it how I want it to work. So far that has been working real well for me.

Steve,

It is time.  Can you share with us everything there is to know about the GPZ 7000?

Mitchel

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