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A Walk With The Midget Coil


Andyy

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I think the GPZ with 14 inch coil is even better than the SDC regarding EMI. Btw, the SDC is pretty darn good on bedrock. Not sure if the GPZ with 14' or Xcoil would really make a differenc here. Now, open field that's different.

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10 hours ago, phrunt said:

That didn't stop me with the first time using my GPZ..... same mistake, didn't screw the coil cable up tight enough at the control box.

I guess with people not used to changing coils on the GPZ it may become a problem if they don't realize how tight that cable has to be, it seems the slightest movement sets off the detector so it's vital cables are tight.  

If I did incorrectly plug it in, it would have been the first time ever.  When I switched out the coils it was not noticeable, but it was the only thing I did differently.  From my previous coil testing I had been swapping out the coils all of the time.  For now I will keep an eye on it but it is running 100% for now (knock on wood).

 

7 hours ago, Gold Catcher said:

I think the GPZ with 14 inch coil is even better than the SDC regarding EMI. Btw, the SDC is pretty darn good on bedrock. Not sure if the GPZ with 14' or Xcoil would really make a differenc here. Now, open field that's different.

Gold Catcher, I agree, I have seen the SDC on bedrock and it is excellent at this.  The main reason I got the 10" coil to try was so that I didn't have to buy a $2K SDC.  Because in my mind the best combination out there is the GPZ and the SDC.  But aside from having a 2" bigger coil, I believe the 10" coil is as sensitive and probably better signal processing.  It would take someone like JW to do this test.  I have yet to find anyone willing to do this test.  My previous testing results putting the SDC against the 10" coil was only comparing depths of small size nuggets given from a friend who I meet up with on rare occasion that owns an SDC (and who is very successful with it)  Now under the powerlines ... I'd be curious of that too.  I can't tell you how many patches I have under or very near power lines.

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14 minutes ago, Andyy said:

Because in my mind the best combination out there is the GPZ and the SDC

Good points, Andyy. I think the 8 inch round has it advantages and is just made for what the SDC is supposed to deliver. I also like its versatility and compactness, but that's outside of performance. Looking forward to hear more field reports from you and others who have the 10 inch Xcoil. What I would be interested in to know is if the performance of the GPZ technology is somehow dependent on what type of coil you are using, in particular on the type of coil winding. It could be that GPZ is just not working the same for every coil out there. But I am no expert in this and it could very well be that GPZ technology is just plug and play. Perhaps JP would know? 

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I think GC myself as an early  bird, the 10" on the GPZ has taken the SDC out of the equation in most situations and ground types. ( I own both) Running them both at quiet settings there is little difference but crank the 10X on Z up and it kills the SDC in both size and depth, and if one leans towards open mindedness and wishes to fully exploit the Z go Manual GB with just a few up and down coil strokes with QT depressed there is naught out there to compare with. The X coils I have, have paid for themselves many times over bar the latest 15x10 which hasn`t a color yet. But that`ll change in a month or so.

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37 minutes ago, Norvic said:

Running them both at quiet settings there is little difference but crank the 10X on Z up and it kills the SDC in both size and depth, and if one leans towards open mindedness and wishes to fully exploit the Z go Manual GB with just a few up and down coil strokes with QT depressed there is naught out there to compare with. 

Good info, Norvic.  Thank you for sharing.  You reminded me that JP also mentioned that manual GB can give more depth.  I tend to just leave my GPZ alone but should experiment more as you have done.  

I think the GPX machine, itself, had a lot of variations.  Some 5000 machines can hear really small gold while others, with the same settings-using the same coil, cannot  hear a damn thing.  I don't see that on the GPZ machines.  They all seem to run fairly similarly from what I have seen.  Well until Xcoils came along that is.  

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15 hours ago, Gold Catcher said:

Good points, Andyy. I think the 8 inch round has it advantages and is just made for what the SDC is supposed to deliver. I also like its versatility and compactness, but that's outside of performance. Looking forward to hear more field reports from you and others who have the 10 inch Xcoil. What I would be interested in to know is if the performance of the GPZ technology is somehow dependent on what type of coil you are using, in particular on the type of coil winding. It could be that GPZ is just not working the same for every coil out there. But I am no expert in this and it could very well be that GPZ technology is just plug and play. Perhaps JP would know? 

A few salient points based on logic and please this is not a flame post before anyone gets all bent out of shape.

Firstly there are major differences between Monoloop coils and DOD coils, monos are way more sensitive to variations in ground signal, salt signal and saturation signal however in the case of the SDC the narrow band width timings it uses are specifically designed to provide max sensitivity to shallow fast time constant nuggets but at the cost of overall depth, the narrow timings design is why the SDC does so well in salty, highly variable ground types. On a direct comparison in Fine Gold on an in-situ 1/2 gram nugget at 9 inches in noisy variable ground the GPX 5000 walked all over the SDC for strength of target signal (SDC wouldn’t respond until 4 inches of packed soil was excavated), whereas on tiny little surface nuggets especially in noisy ground the SDC reigns supreme.

Secondly the 8” coil on the SDC also helps it immensely in salty ground, the smaller the coil the better it works in a salty environment, a small coil also helps with EMI but as has been noted the SDC is still pretty twitchy around EMI sources.  

For GPZ there is a strong correlation between different coils and control box combinations, so if you swap coils and control boxes the GB and X balance will be quite a bit different from one unit to the next, however once calibrations are performed there is very little difference between units. This means that not all electronics are exactly the same nor are all coils the same, however the controlling software that drives them is assuming the coil being attached is within reasonable range of tolerances required. Not being able to correctly calibrate any of these factors is not good in my opinion. 

A lot of the discussions around coils for the GPZ is mainly based on size configurations, obviously a smaller coil is going to result in less EMI, less Salt signal and more sensitivity, these reductions will aid somewhat in other areas of concern with regards to X balance and explains the users who’s results reflect environments that are conducive to not needing to calibrate. My feeling is operators should look on these options as being like the old days of Normal timings on the GP series when the Smooth class of “ground noise and hot rock ignoring“  timings became available. In those days noisy ground required the use of a DD coil, quieter more homogeneous soils allowed the use of Monoloop coils, those of us who had access to quieter ground types could enjoy the benefits of what a monoloop had to offer or developed skills to be able to listen through the ground clutter for the deeper penetration abilities of a monoloop.

 

 

 

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