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Coin Air Tests For White's V3i?


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What could a person expect to be the normal air test on a dime and nickel using the stock coin/jewelry program with the v3i and the stock 11" D2 coil?

Thanks in advance

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While air tests are kinda fun and they help you familiarize yourself with the machine settings the chances of you finding a dime or nickel at 11" in the ground are slim ..... So many variables and depending on the level of mineralization in your particular ground will have the biggest effect on overall performance.... 

Concentrate on getting a good ground balance for best performance... 

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Air tests can tell you if you have a bad machine/coil. They can tell you the best you can hope for in very low mineral ground. And as the link I provided clearly shows, air tests can offer some real clues as to what modes or settings might be worth exploring in the field.

The biggest thing air tests can't tell you is exactly what you have already mentioned johndoe - how well does the detector eliminate ground effects? I have seen one detector air test better than another detector and then have the results flip to the exact opposite in a ground test. There is almost nothing more important than how well a detector eliminates the ground. The worse the ground is that you work in, the more important this is. So while air tests can teach many things one thing they really can't tell you is how the detector performs in bad ground. In fact, some of the machines that air test the best do the worst in the ground!

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The reason I was asking about air test figures is I recently bought a used V3i from a guy I hunt with 3-4 times each year.

Two years ago the machine, (same machine) was sent to me to run though my test garden.  The machine performed almost flawlessly, detecting each target at many different depts.  One target in particular is extremely hard for most detectors to respond to.  The target is a very small copper rivet at 7" deep.  After buying the machine, the test garden was one of the first stops,  surprise the three deepest targets failed to respond.

 

Did some simple air test and the air response failed short of the depth of these targets.  I checked the coil connections, all are tight, then after exhausting all my options I did a master reset on all settings and programs and still no change in the air test. 

You are absolutely correct in the fact bad ground subtracts from depth, by huge amounts at times.

I was really wanting a starting point of an air test in the coin/jewelry program  to see where I machine actually is.

I'll chance to another coil tonight and hit the test garden again.

 

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I assumed you knew this stuff Mark but I always toss in extra info on threads for those who may not know. 

White's D2 coils had a high failure rate early on. This link has information on how to test the coils. http://forums.whiteselectronics.com/showthread.php?55295-V-rated-coils-not-common-available

Good coils should be able to run RXG=15 with Tx Boost=On without overloading in an air test. If an overload occurs running the V3i separately in each frequency will reveal at which frequencies the coil is failing at (it could be all three).

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25 minutes ago, Steve Herschbach said:

I assumed you knew this stuff Mark but I always toss in extra info on threads for those who may not know. 

White's D2 coils had a high failure rate early on. http://forums.whiteselectronics.com/showthread.php?55295-V-rated-coils-not-common-available

So it is highly likely the coil I have might be bad.  He bought the V3 new in 2010 and sent it in for an update to V3i.  I'll do the overload test tonight and post my results.  Doesn't sound good since the machine is out of warranty by now.

But I did receive a white and black 10 x 12 SEF coil in the deal, maybe one of those might work okay.

 

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One thing I've wondered about is variation among (nominally) identical devices.  Hypothetically suppose I buy 10 of the same coil from different dealers (so maybe different run batches).  How consistent will their performances be?  You can ask the same question about the rest of the test instrument -- I.e. the detector control box hardware.

I know from reading Dave J.'s posts that coils that aren't made to work on a particular model will sometimes work on some specific units and not on others.  This tells me there is at least some variation in hardware.

It's likely that the manufacturers have done these tests, or similar, but I don't know that they 'publish' their results.

 

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2 hours ago, Steve Herschbach said:

I assumed you knew this stuff Mark but I always toss in extra info on threads for those who may not know. 

White's D2 coils had a high failure rate early on. http://forums.whiteselectronics.com/showthread.php?55295-V-rated-coils-not-common-available

I remember the trouble they had with the first D2 coils but never thought it might be my problem.  Oh well .......

I'll do the test described in the post and see if the coil passes or not.

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48 minutes ago, GB_Amateur said:

One thing I've wondered about is variation among (nominally) identical devices

There is certainly variation in older detectors and current analog models. Far less with modern surface mount digital models. Coils however are always an issue, especially older ones, and especially DD coils on very high performance models like the V3i. The higher the frequency, the harder to get it right.

The V3i coil has to be nulled at three frequencies and it is usually the 22.5 kHz frequency that fails.

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