VDI number stability

[Frank L]

How in the all fired cat-hair is a body to determine what to dig when the VDI numbers won't lock on? Is this an indication of trash or what?

FranK L/TX

 

[JAKETHESNAKE]

First off you need to decide what you want to find coins,jewelry or gold bricks. Not knowing which coil your using and assuming it's the 950 that your using slow down and look for the VDI number your looking for. For instants quarters are around 84 to 86. It's probably just really trashy go somewhere where there's not so much trash until you get the hang of it. you'll be okay and later get another smaller coil like the 4x6 or 5.3 HAPPY HUNTING.

 

[tab-nabit]

I don't know about the MXT (probably shouldn't be here), but I have used machines that may get a better lock when sweeping the coil at a faster speed across the target. May change depth too. And don't know if still true to what machines this day, but some were known to have the display and audio as 2 separate circuits. Hence, many determine the main decision based on the audio - was known a target responded to audio and not visual display mainly to deep signals. Hitting target at different angles trying to separate from multiple targets under coil at same given time - small coils in trashy areas - common.

 

[Blazer-12]

Try reducing your sensitivity in steps until you get a stable VDI.

 

[;hgarr]

Hi Frank L....This technique for id'ing a iffy target works best with a DD coil on a DFX, but almost as well on a MXT or M6.,, Once you hear a target, try to pinpoint it off the front tip about an inch from the end, with the back of the loop lifted about 2 inches (about 10 degrees). When you get it pinpointed, and if the sound is a little iffy, hover the target by fairly rapidly wiggling the tip from side to side about one inch total. What hopefully happens is that the iffy tone will suddenly turn into a good (or bad) steady tone ---like magic---such that it is easy to tell a good target from the bad. Hope this is helpful. Works well in heavily mineralized and trashy soils but gets a little tiring after awhile....Best of hunting to you....How.

 

[Larry (IL)]

The best way to fully understand your detector and what it is telling you with the visual and audio signals is to dig everything in the beginning. You will soon learn and link patterns of the signal and targets. In the future, you will feel confident of what you are passing up as trash and when in doubt dig it, you just might find that some of your best finds were "maybes".

 

[Frank L]

Thanks folks, for the good advice. I'll see what happens. Frank

 

[BarberBill]

It is often trash, but could be several items close together, also. One might be a good target which is why you see the advice to "dig everything". One trick I use on my MXT that often helps, especially with the smaller coils, is once I'm centered on the target, I just slightly wiggle the coil side to side and front to rear. Not SWING , bui just wiggle. Often this will settle down the display - always worth a try anyway.
HH
BB

 

[gerber]

Hi Frank,

Stability in the VDI numbers is also based on the depth of the target. Usually, when you've located a target that's only a few inches deep with wildly divergent VDI, you'll find it to be trash. However, as you go deeper, a little more variability is fairly common. Also, the classic VDI identifications for targets become less certain, e.g. in my experience, nickels at 6 or 7 inches often register higher or at least differently than the classic 18-20 signature. In other words, the deeper you go, the less you should rely on rigid VDI for identification. For some of the deepest targets, e.g. 8 inches or more, you may simply find readings ranging widely from -95 to 94. I tend to dig these deeper targets--lots of nice surprises sometimes.

HH,

Dan

 

[B.T]

Hello Frank. I live over in Australia and use the MXT mainly for gold nuggets and specimen hunting. I have found though that in really bad ironstone highly mineralised ground that the VDI numbers in Coin mode can give wrong IDs when the sensitivity is set too high. Sometimes the ground is so bad that you cannot do anything to help it. I'm talking of hunting on bad goldfield areas here. When its like this I turn the gain right down and use Prospecting mode for hunting coins. If there is a lot of rubbish like bits of old tin and iron you can have, in coin mode, the VDI numbers bounce like crazy but good targets will lock on no probs. Seeing them bounce in that type of scenario is normal and nothing to worry about, goodies will lock on. If you get a few rubbishy sounding signals interrupted by a good one slow right down and narrow down your sweep as you move across the targets trying to analyse each one if you can, sometimes that is a good one trying to poke through the bad.
Sometimes a fast sweep is your worst enemy when the targets are thick and close together as the machine reads a good one then a bad one then a good one and so on within seconds not given time to lock on. This will cause much VDI confusion and have you walk right over a good keeper. Your sweep speed in this situation is determined by the amount of targets and how close they are to each other. You may then find your sweep speed well below the recommended one of 2 seconds. Swinging your coil over a dozen targets at 2 seconds sweep speed will see you cover multiple targets at once and if the bad ones that are amongst the good are of the over-riding size in comparison to the good it is more than likely that the machine will read the bad at the expense of the good. Prospecting mode will get the best results for gold with a sweep of around 6 seconds from one side to the other, go faster and you will kiss the majority of targets good-bye. I am in another world over here though and for you it could be totally different, just some thoughts.

 

[Bill D. (VA)]

I too was disappointed in the wide spread of VDI readings I was getting when I first started using my MXT. I had been used to the XLT which averages VDI readings when multiple passes are made over a target (wiggling), which made it appear it was locking onto a fairly specific VDI. But the MXT works a bit differently as it shows a distinct VDI with each pass. Depending on the target type and orientation, the VDIs can vary considerably (especially from opposing directions). My experience is that when the VDIs vary by a large extent (like jumping between the 30s and 70s for example), its a good chance its trash that has an irregular shape. But even for good targets its not uncommon for the readings to be 20 points apart. But for a coin or button in a true horizontal position, the VDIs will be quite consistent. Its hard to explain here, but once you get a lot of experience digging targets you'll understand what I'm talking about. Its really a non-problem unless you're always hunting very trashy ground. If that's the case, a smaller coil will lessen the impact of the wide-ranging VDI readings. Good luck .... Bill

 

[bula]

One thing to watch for is if you are getting several numbers such as penny, dime, quarter, but none will lock on you are probably looking at a coin spill & all of the readings are correct.