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Coin Air Tests For White's V3i?


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Care to expand on "nulled"

 

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It goes to the very heart of what "induction balance" is all about. The V3i and its related documentation is a virtual class on induction balance technology and how it works. From Spectra V3i Advanced Users Guide by Carl Moreland, page 3-2:

"V3i uses induction balanced loops which rely on a “null” between the transmit coil and the receive coil. The quality of the null may determine the point at which the detector overloads, especially when running Tx Boost along with high Rx Gain settings. Null quality varies loop-to-loop, so some loops may overload at lower gain than others."

And from Coil Basics by Carl Moreland, page 2:

"a second coil can be placed such that it inductively couples with the transmit coil. By careful placement, we can also get the second coil in a “null” of the transmit field, such that there is no coupling. In such a case we say the coils are inductively balanced, and this is where the term “induction balance” (IB) comes from."

The V3i pushes coil design hard by running separately at three different frequencies at high TX output. Each frequency must be separately nulled for optimum performance. There are ways to fudge which makes coils appear to work fine but which result in degraded performance. I can slap a 13 kHz F75 coil on my 19 kHz G2 and have it appear to work fine, but the fact is there will probably be ground balance and target VDI issues.

It is stuff like this that makes a layman like me question how Garrett can be getting optimum performance with AT coils on detectors running at 13.6, 15,  and 18 kHz? Just how far can this be stretched?

The X-Terra models show how a detector can sense and compensate for different individual coils tuned for different frequencies. In theory this has a better end resultant than than trying to get one coil to run best at three different frequencies. In Garrett's case the coils are all the same, probably wound for 15 kHz but with loose enough tolerances that 13.6 and 18 kHz are within an allowable range of offset, and with possible electronic compensation going on in the circuitry. Just a guess on my part however it is this sort of fine tuning that does make or break those "edge of performance" differences between VLF detectors these days.

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Found out one thing, every coil I got with the v3i are not V rated. All failed the test.

Now I must admit the main reason I wanted the V3i was to use the high frequency to jewelry hunt.  Now I'll have to find a v rated coil and maybe sell the others.

Ever learning and never learning any lessons.

 

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5 hours ago, Mark Gillespie said:

Found out one thing, every coil I got with the v3i are not V rated. All failed the test.

Now I must admit the main reason I wanted the V3i was to use the high frequency to jewelry hunt.  Now I'll have to find a v rated coil and maybe sell the others.

Ever learning and never learning any lessons.

 

 

How high can you get the RX gain before you start getting instability?

 

Chances are those coils will still work just fine and the likelyhood that you would be running at 15 is slim.... Running that hot will usually cause all kinds of instability in mineralized ground. 

The V3i does not require you to max all the settings to get best performance......

Remember........ Mo hotter is NOT always mo better.

You may also find this helpful.... http://www.metaldetectingintheusa.com/files/v3i-sensitivity.pdf

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You'll need to map your Gain and Sensitivity settings to get a grasp on whats what.

Here is mine... Its a work in progress.  I believe this is with the 9.5 concentric

Mike    

 

V3 Gain.jpg

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You're right

20 hours ago, johnedoe said:

One coil, white SEF requires a RX of 4 to prevent overload while in multi-frequency and at that a 4" dime is almost silent.  It will not run the single high frequency option at all.  I'm pretty sure it's a bad coil.  It is very difficult to get a good ground balance settings. 

The other SEF will go to RX 7 before overload.  The D2 coil reacts about the same.  I'm not really wanting to run with TX Boost, but noticed these differences and was curious. 

I really bought the V3i for one main reason and that is to jewelry hunt.

So I'll be looking for a White's 6x10" Eclipse DD Search Coil. 

How high can you get the RX gain before you start getting instability?

 

Chances are those coils will still work just fine and the likelyhood that you would be running at 15 is slim.... Running that hot will usually cause all kinds of instability in mineralized ground. 

The V3i does not require you to max all the settings to get best performance......

Remember........ Mo hotter is NOT always mo better.

You may also find this helpful.... http://www.metaldetectingintheusa.com/files/v3i-sensitivity.pdf

 

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That is an awesome settings chart Mike.

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I would just send everything into White's.

They will take care of you without taking an arm and a leg to get things fixed up for you.

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Thanks Mark,

Sometime my charts are hard to read as I'm making them for my own reference.   They also get a bit time consuming so it takes a while to complete them and I have to be in the mood to do so after I get the basic information I'm looking for out of them. 

HH
Mike

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