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Question On Ground Balancing A Detector


DSMITH

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There is a debate on another forum about ground balancing a detector
this was stated by another poster
A POSITIVE ground balance means that the machines threshold INCREASES in volume as the coil is LOWERED TO THE GROUND. A NEGATIVE ground balance means that the machines threshold DECREASES as the coil is LOWERED TO THE GROUND. To achieve a NEUTRAL ground balance you want the machine to do NEITHER as the coil is LOWERED TO THE GROUND. For best results, especially for beginners who might be reading this…you want the machine to be SLIGHTLY POSITIVE…the machines threshold should INCREASE VERY SLIGHTLY as the coil is LOWERED TO THE GROUND.

Again…absolutely no disrespect, but this is how this subject has caused SO much confusion over the years. People who have spent hundreds or thousands of hours running a metal detector STILL don’t know the basics of how they work. And ground balancing is about as basic as there is.

I just do NOT understand how this can be. can someone explain to me what the purpose of ground balancing a detector as I know what I have been told but just want to make sure I am understanding it correctly

this was stated on another site but to me it does not seem totally correct or is it correct

everything I understand about ground balancing it does not have anything to do with the threshold or does it just trying to clear this up in my mind

 

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Set the threshold to the minimum that is stable. Start to pump the coil up and down on the ground. If a noise change is heard when going near the ground turn the ground balance one way if it get loader or quieter turn it the other way till no change is heard. When the ground has small variable hot rocks a little bias one way or the other can help reduce this annoyance. How is that for simple.    

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47 minutes ago, geof_junk said:

Set the threshold to the minimum that is stable. Start to pump the coil up and down on the ground. If a noise change is heard when going near the ground turn the ground balance one way if it get loader or quieter turn it the other way till no change is heard. When the ground has small variable hot rocks a little bias one way or the other can help reduce this annoyance. How is that for simple.    

that does make sense to me but I guess my question is

Does the Ground balance play any part in the threshold ??? to put it simpler

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What exactly is wrong with the quoted paragraph? You act like it means the poster does not know what they are talking about. Looks like a cut and paste from an operating manual to me. Just standard stuff. I generally ground balance slightly positive when nugget detecting with a VLF.

You use the threshold to get a proper manual ground balance by listening to what it does when the coil is moved in relation to the ground. In theory a proper ground balance gives you a more stable threshold, by lessening ground reactions. The two are not entirely unrelated.

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8 minutes ago, Steve Herschbach said:

What exactly is wrong with the quoted paragraph? You act like it means the poster does not know what they are talking about. Looks like a cut and paste from an operating manual to me. Just standard stuff. I generally ground balance slightly positive when nugget detecting with a VLF.

You use the threshold to get a proper manual ground balance by listening to what it does when the coil is moved in relation to the ground. In theory a proper ground balance gives you a more stable threshold, by lessening ground reactions. The two are not entirely unrelated.

I was not saying there is anything wrong with it at all, i am just trying to clear it up in my mind, i am no expert and its been so long since I have detected and I am just getting back into it that I am trying to re learn everything and re understand everything if that makes since my mind just does not seem to pick it up as quickly as it once did and I just did not recall the ground balance having anything to do with the threshold 

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If you still just have the Goldmonster.....you don't need to worry about the threshold part. Just ground balance often and until the Goldmonster quiets down.

If you are using the X 705 in prospect mode, then you should listen for a slight threshold volume increase as the coil approaches the ground. Otherwise ground balancing the X 705 in its disc. mode is easy.

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There is your answer from "Geotech". The threshold is set to what you like but the volume will alter when the coil receives a positive or negative unbalance signal due to wet salt, iron effect or most importance target signal. You only want the target signal, so you remove wet salt, iron effect, by ground balance between air and ground so no sound effect comes from the ground and interferes with the target signal

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Is there much difference in actual performance between having a GB based on AC verses DC signal? 

Is a detector always just one or the other?

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2 hours ago, JCR said:

Is there much difference in actual performance between having a GB based on AC verses DC signal?

Not really. In most modern designs the GB is applied at the demodulator (using variable timing) before the filters convert the signals to AC. But you GB the machine by listening to the ground after the filters. You could apply GB after the demods & filters, which is what the GoldBug2 does. The early VLF detectors did not have target filters so what you heard was always DC signals, but the method of GB (variable timing applied to the demod) was the same as it is now.

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