Original Xterra 1st generation 6" Coils DD vs Concentric

[bigtim1973]

These things certainly are getting hard to find for sure!

Anyway, does anyone have both the small 6" concentric and 6" DD version of these by chance that could offer their 2 cents?

Do you notice a depth difference between the concentric vs DD or are they kind of neck and neck?

From my own experience I do find that the concentric will correctly ID items better than a DD coil will.

I know the DD coil will get in between iron better but when both coils are 6" I do think they would be somewhat equal.

Thanks, Tim

 

[Old Longhair]

These things certainly are getting hard to find for sure!

Anyway, does anyone have both the small 6" concentric and 6" DD version of these by chance that could offer their 2 cents?

Do you notice a depth difference between the concentric vs DD or are they kind of neck and neck?

From my own experience I do find that the concentric will correctly ID items better than a DD coil will.

I know the DD coil will get in between iron better but when both coils are 6" I do think they would be somewhat equal.

Thanks, Tim

The only 6" concentric coil is in 7.5kHz for the Xterra. The only concentric coils for 18.75 and 3kHz are 9".

 

[bigtim1973]

I thought there was an 18.75 concentric but I see now that there is not.

 

[bigtim1973]

Ok then again, does anyone have both that can verify if one is slightly deeper?

 

[MuddyMo]

3khz concentric is very deep but the 18.75 will false less on iron. I still have the 3k. I also have the 6” 18.75.

 

[Old Longhair]

Depending on your soil conditions (of course), the deepest 6" is likely going to be the 3kHz in Prospector Mode. The Iron Mask feature will knock out most nonferrous targets if avoiding those is important.

 

[bigtim1973]

This is somewhat of a follow up on my original question I asked here.

So I have managed to get my hands on a few original coils. One is supposed to be brand new old stock Malaysia made 6 inch concentric coil

The other coils I have compared it to are the 9x5 HF elliptical and the 6 inch round HF.

My 6 inch hf coil is an original Ireland made one. The elliptical is Malaysia made.

In my soil the HF 6 inch 18.75 khz coil runs neck and neck with the 9x5 hf elliptical coil


Now the Malaysia made 6 inch 7.5 khz concentric compared to the 6 inch 18.75 DD coil is downright pathetic.

I have to turn the sensitivity all of the way up to hit a 7 inch nickel where as the HF round DD coil I can hit it with a sensitivity setting of 18.

I am shocked actually as in mild soil conditions a concentric is supposed to be a deeper seeking coil.

But in this case it is overwhelmingly disappointing.

I have a feeling it could just be the particular coil I have that may have a problem

But if my memory serves me well....I believe I had bought a concentric 6 inch coil several years ago that was I was not happy with as well.

So it just my be the difference between the 2

 

[Old Longhair]

IMO, a DD coil will always outperform a concentric coil in moderate to heavy mineralized soil situation. The slice of ground (volumetrically) that the DD coil has to compensate for is much less than it has to with a CC, and that has a direct effect on depth capability.

I never understood the attraction to elliptical coils. They are depth limited by their width, and separation limited by their length. It makes total sense that a 5X10" wouldn't see any deeper than a 6" due to the similar widths.

 

[bigtim1973]

But with half of the sensitivity though.....i can understand a difference of 3/4 sensitivity difference but, a difference of a little over half?

I think there is more to it than just the design

 

[Old Longhair]

But with half of the sensitivity though.....i can understand a difference of 3/4 sensitivity difference but, a difference of a little over half?

I think there is more to it than just the design

Another thing to consider is that a Nickel is always going to respond to the HF signal transmission better/more/harder than the MF. Between the difference in response due to the different frequency and the difference in soil volume in the detection field, I can see why there could be a significant sensitivity difference.

I'm not saying that there couldn't be something in your coil's manufacture that explains the discrepancy, but that it's too tough to call without comparing apples to apples.

 

[bigtim1973]

It should not be this bad I know. I understand the lower conductor vs lower frequency but this is way out of line IMO