Wonder why the xterras dont lock on nickels well like it does on other coins

[Trackerman]

Hello ive owned a few xterras now and have noticed that with the stock 7.5klhz coil the xterras dont id nickels well . The numbers jump around quiet a bit. Now with quarters my xtterra 50 allways reads them at 45 and rarely at 42. As for dimes it reads them at 42 mostly and sometimes 36 .Pennys are 36 if i recall as well. The id locks well on pennys quarters dimes but not well on nickels or pull tabs. Wich makes it really hard to id gold rings and gold jewlry. I have noticed this on the xterra 70 , Xterra 50 and the xterra 305. Now with the higher frequency coils it ids nickels a bit better. Any ideas as to why the xtteras dont id & lock on nickels very well?

 

[Digger]

You said it yourself, it is the frequency of the coil, not necessarliy the detector. Higher freqs are better suited for lower conductive (and smaller) targets. Lower frequencies are better suited for higher conductivities (and larger) targets. With that said, 99% of the nickels I've found hit at 10 or 12. And that would qualify them for being "lower conductivity", compared to silver and copper. In the places I hunt, the main thing that mimics nickels are the corroded top portions of 12 ga shotgun shell casings. JMHO HH Randy

 

[tony (Orlando FL)]

I never gave it a second thought, I just figured nickels have slight composition changes over the yrs which made em read similar but not exact. These changes I am referring to are nickels made over the yrs (new coins), and not including what is being done to their characteristics by laying in the ground all these years which is surely another factor.

 

[7centsworth]

I used to have 50 and it usually read 42 on quarters and 36 on dimes nickels lock on better that pennies usually 12 . My ground here in ky is not real mineralized though.

 

[Trackerman]

Now the strange thing is i have a garrett ace 250 and it only has a 5.9klhz frequency and that sucker locks on nickels real well and pull tabs too! Im guessing with the xterras its the design of the machine and the lower frequency in its case doesnt help. Guess ill have to get the 18.75klhz coil for nickels and jewlry.

 

[tony (Orlando FL)]

Trackernan-

You mention that the ace 250 locks on real good...... I would bet that IF the ace had a digital ID meter, it too would be wandering around on various items, like nickels, just like the X50 does.

When you consider the ace has maybe 14 segments a target can fall into, and a X50 has ( I am guessing here now) maybe 25 possible target ID values that means the ID is more granular and will seem to hop maybe 2.5 Xs more than an ace 250 would. Its not that the ace is locking on better, its simply the ace segment width might be VDI #s 8-14 or a value of say 6 or 7 VDI #s wide and you simply cant see the jumping of the numbers within that segment.

If you had an XLT which has almost 100 vdi #s for non ferrous items, the xlt just might jump two to three times more than the x50 simply by being able to do so.

I hope this makes sense because its tricky to put in words while not using your hands and sketches etc.....

 

[Trackerman]

Ya that makes sense the more target segments you have the more difficult to lock on targets. The Ace 250 just has a real simple user interface and does surprizingly well on nickels and foil and pull tabs wich i like because thats were the jewlrys at. Now i really like the xterras and thats why i was trying to figure it out. Looks like ill be getting that 6inch 1875klhz minelab coil to resolve the nickel problem down the road Thanks.

 

[Goes4ever]

ever since i switched to the 3khz coil, I have not had one single nickel come in at 10-12
I have dug several V's, buff's, one shield and several jeefersons, and they bounce around in the 30's.........believe it or not. I think I am digging an indian and an old nickel pops out!

 

[Mtnmn]

When bench testing my 6" DD HF coil, I was getting an inch more distance on nickels than on quarters. I now realize it was the higher frequency of the coil which allowed it to hit so well on nickels. Now if it will only help me find a little glacial gold.

 

[TURNMASTER]

Most any nickels I have dug I believe came in between 10 and 16 but never 18. New or old but the few oldies were deeper and I found them with the HF coils.

Jeff

 

[dignit]

You have mentioned that you have used a higher frequency coil...I have the 18.75 DD coil and a concentric coil, and the DD is about the only coil I have used so far. It ID"s nickels correctly almost all of the time. I can tell by the difference in the pitch and tone of the signal whether it is a nickel or a pull tab. Sometimes those broken off ends pencils which hold the eraser like to fool me into beleiving they are nickels. Nickels tend to squeal louder when pin pointed. Are you re-balancing the ground and noise settings after you change coils? This can make a world of difference, even when moving around different areas of you hunting grounds.

 

[Diggler]

I have found that the 305 with 18.75 concentric, an unfaltering 12 is a nickel. Slaw etc in the same range might hit a 12 but dance up and down a little. But a smooth, steady 12 has been a nickel every time so far.

 

[Trackerman]

perhaps steady 12s on the 18.75klhz coil but not with the stock 7.5klhz coil.

 

[Goes4ever]

or the 3khz.......

 

[Mtnmn]

The Ace 250 may hit real well on nickels (and pulltabs), but I suspect it is much easier to tell the difference with an X-T. In my area we have a ton of pulltabs very close to the nickel range, but very seldom do I get fooled anymore. Though here we don't get the high nickel readings some guys seem to have elsewhere.

 

[kd7aik]

The 18 freq eliptical locks on nickels well i usually get them at 10 to 14 but have dug older deeper ones that read 8.

 

[Trackerman]

The Ace locks on nickels very well . The xterras dont lock as well nor are they as easy to read nickels with them trust me i own an xterra and a Ace 250

The Ace 250 may hit real well on nickels (and pulltabs), but I suspect it is much easier to tell the difference with an X-T. In my area we have a ton of pulltabs very close to the nickel range, but very seldom do I get fooled anymore. Though here we don't get the high nickel readings some guys seem to have elsewhere.

 

[BarnacleBill]

Let's begin with a graphic which I didn't create but have posted several times. It will provide an anchor point for the discussion.

[attachment 145634 DiscriminationChart.jpg]

The Disc numbers have been arbitrarily assigned just as they are with any ID type metal detector, but this one appears to be for a manual Discrimination knob. However it is still valid for use in discussing the topic at hand. Most of the Disc numbers are whole numbers, but notice that within certain target ranges the designer felt the need to assign partial/decimal values to meet a particular design parameter.

A tale of three detectors

Let's assume three targets in the Nickel range. On a given day we have a .22 cal short slug that is below the Nickel in phase response, the Nickel which is in the center of the three, and an intact Pistol Cartridge above in phase response

The ACE 250 & X-Terra 305 each have 12 ID Segments. Does that mean that those ID segments line up perfectly and from one detector to another? No! It may be that the Nickel ID segment is very wide on the ACE250 as it is designed primarily as a Coin Shooter and will ID all three above mentioned targets as a Nickel. It may also be that the X305 will have the slug fall below Nickel in ID or the cartridge above in ID response. I can tell you from experience that the X-Terra's do indeed have higher resolution in the Foil/Nickel/Tab range for better jewelry/relic hunting with 7 non-ferrous ID segments below Zincs for the X305. That leaves 4 ID segments of resolution in the upper conductive scale which means targets will appear to lock better because the ID segments are wider.

An interesting contrast to the above is the the Fisher CZ-70 Pro which only has 7 ID Segments. It is a very well respected and widely used detector that can be said leaned towards Coin Shooting primarily. But despite having only 7 ID segments, does that mean all three of the above targets would get lumped into the Nickel segment. No! The break point is picked by the designer to meet a need.

There's also a little bellybutton issue which should be kept in mind. The ACE250 is a detector designed for the U.S. market, and therefore the width of the ID notches and their placement is aimed at that market, complete with the screened Icons on the faceplate. The X-Terras are built for a worldwide market, and even more so with the X-Terra 2 series as the face plates are Icon based controls. The U.S. is not the market with the greatest potential sales growth in this hobby.

Below I include a comparo of the ACE250 & X305.

[attachment 145635 Ace350b.gif]

HH
BarnacleBill

 

[Trackerman]

Your article is very good BarnacleBill you are quiet skilled i must admit. However there is one factor here and it is when both machines are bone stock the Ace will not only lock on nickels better its also locks on other coins better as well. iding simpler on the Ace than the xterras. If one is doing a quick hunt and wants simplicity plus acurate reads and results the Ace really does a fine job. Also the Ace seems to like foil a bit more as well and ive read that much gold jewlry will read as foil and this is true because i found a gold cross in the foil to nickel range with the Ace.The fact that the xterras are set up for european use more than American is not necessarlly a good thing for Us users. Now if Minelab would have made there higher frequency coil a 15klhz it then would have been not only a good coil for coins but also for jelwry. Simply put at less than half the price of an xterra the Ace has similar performance if not better. Some will argue and say never but as far as pound for pound dollar for dollar the Ace cant be beat.

 

[kd7aik]

Ive found more nickels with my compass xp pro then any other unit ive owned hit nickels an gold harder then silver