GPZ 10" Xcoils In USA

[Andyy]

As promised, I got out this morning to do a review on a new Russian Xcoil that I received.  But let me state firstly that I am not a dealer, I paid for this coil myself and have no self interests other than reporting what I find as I see it.  So here it goes:

I headed off to the gold fields of Arizona at about10:15pm last night.  It was 105F outside but it was dropping.  So it looked like this was going to be a fairly comfortable night for detecting.  The goal of this trip was:

1) compare the Russian 10" Xcoil to the 14x13" ML coil in respects to finding gold

2) check ferrite balance

3) check knock sensitivity

4) review overall design

The first patch I tested was one in which I had only found small gold (nothing over .3g).  In total, I am lucky if this patch gave up 15 grams, but it was very fun.  And I gridded this area to the best of my ability.  Rough dimensions are 50'x50'.  It is unlike any of my other gold area I have been to.  There is no quartz on the ground, but seems to be a basalt looking grey covering up a red gossan type material (which the gold is in) There are areas on this hill where you cannot swing a detector it is so hot.  And hot rocks are the norm, here.   Once on location, I began with the standard coil, dropped the ferrite ring and ground balanced.  I also followed up with noise cancelling, etc.   Then I proceeded to recheck an area which had a dense concentration of nuggets, previously.  I found nothing but I succeeded in warming the machine up.  No knock sensitivity, threshold was a little ratty with the EMI, but nothing out of the ordinary.

I ran the most conservative settings I know.  There are much better settings, but I wanted to know how the coils would operate without optimization.  Settings are below:

     High Yield/Normal/Sens=4,Vol=8,Thresh=25, tone=53, Vol Limit=7, Ground Balance Mode=Semi Auto, Audio Smoothing= off, Ground smoothing= off

Next, I switched to the 10" coil.  Used the ferrite and checked knock sensitivity.  all was good.  It also, had the same level of noise as before.  so I began hunting.  after 15 minutes or so I had a target and it was a small nugget.  and then another.  At this point I just wandered through the area I had gridded and found a couple more.  Total to this point was four small nuggets.  I didn't want to spend all of my time here so I headed back to the truck.  On the way I checked a wash that I thought I checked previously.  Apparently not good enough.  I found two larger nuggets, now I am up to 6 nuggets for the trip.  But back to the truck  I went to check patch #2.

Now this is where it gets interesting.  It is about 5 minute drive to my new area.  The gold from this area *did* come from quartz stringers and the local metamorphic rocks.  The largest piece found was 5 grams and I believe I found a little over an ounce in total.  Most of it from two washes but some from the adjacent hillside.  Anyways, after parking I started my slow walk to the patch with the 10" coil.  After getting my wits scared out of my by what I think was a bobcat, I continued to the area.  I immediately noticed a problem.  The coil was very noisy.  I tried everything I could and tried to rebalance to the ferrite. But it would not work.  So then I walked back to the truck and got the std coil.  This coil ran smoothly.  So it wasn't my imagination.  Then I switched back again to the 10" coil without rebalancing to the ferrite.  No problem.  It was smooth.  As soon as rebalanced to the ferrite ring, it was out of wack again.  So this was frustrating.  I never did check knock sensitivity as the ground noise was already an issue.  By this time it was 4am and I decided to call it a night.

So it seems that while the coils work well in some areas, there are the areas (as JP mentioned previously) that will give some issues.  The only way to trick it is to use your std coil and lock in the X-balance and then switch coils without rebalancing to the ferrite ring.

Another note I would make about this new coil is that the coil wire itself is thicker and does not like to go into the shaft.  After multiple changings, I found that with a little mid shaft rotation, it helped with this immensely.  The standard coil wire drops right in.

That is really all I have on this, for now.  I am not sure if this helps or just muddies up the water. 

 

 

[Andyy]

Some pics from the first patch hunt:

(sizes in grams: .05/.07/.08/.21/.19/.71 = 1.3g)

[flakmagnet]

Nice report Andyy. Did you make your own patch lead?

X Coil 2021 News

[Jonathan Porter]

This is exactly what I’ve been warning people about all along.

The gold is due to the smaller sized coil which is exciting, bit of a hassle doing the coil swap workaround but here’s a tip for you. If the ambient temperature is say above 20 deg C then the Ferrite balance once done in Semi Auto mode will not vary much even from dead cold. The Ferrite balance is optimal when performed with the coil attached but obviously in the ground you are working there is a lot of X signal present so placing the ferrite on the ground is confusing the electronics because the coil is not optimal like the ML coils are (EDIT: I would say there is a lot of saturation signal present at this location too which is affecting the Ferrite balance). Getting a reasonable Ferrite balance with the ML coil then swapping might be your only work around in this instance.

I hope this thread does not go pear shaped and I appreciate your honesty with your report. At the end of the day you were able to find gold thanks to a smaller coil size on your GPZ, its just a shame it hasn’t been made by Minelab.

JP

[Steve Herschbach]

All commentary on the sayings and doings of other people is to be completely avoided. What other people said, did not say, did do, or did not do is wearing extremely thin with me. Expect all such comments to be deleted / erased from posts. There will be no more warnings about this, just expect it will happen.

[jasong]

The eagle has landed in the US... Thanks for the report Andy!

That can be some gnarly ground down there, and perfect place to test any new piece of equipment. Was the 10" having trouble balancing over the ground in general, or only when you tried to balance over the ferrite on it?

[Andyy]

52 minutes ago, flakmagnet said:

Nice report Andyy. Did you make your own patch lead?

Flakmagnet - Yes, it was my patch lead.

 

46 minutes ago, phrunt said:

Thanks for the post Andyy, it's a shame you had that issue but good to see you got quite a bit of gold, do you think you got them because the smaller coil could get into spots the other coil couldn't or did the 14" just miss them?

I had to look up what a Bobcat is

Simon - I definitely believe the first four were missed by the std coil.  So this tells me that the size of the 10" likely did improve hearing the small gold.  Of course there could have been other factors, but I scrub the coils very slowly.  I checked my gps previous tracks, and it seems like the last two nuggets were not found because I didn't see the wash all together, before.

As for the bobcat, I was walking towards the patch when I saw a large amber reflection. I thought someone put up a mine claim marker at first.   A couple more steps and I saw the other eye open.  That gave me the chills.  Then the large shadow left with a catlike gait.

 

23 minutes ago, jasong said:

The eagle has landed in the US... Thanks for the report Andy!

That can be some gnarly ground down there, and perfect place to test any new piece of equipment. Was the 10" having trouble balancing over the ground in general, or only when you tried to balance over the ferrite on it?

Jason - it seemed really noisy before I ever broke out the ferrite.  No amount of smoothing or ground balancing would help.  But I was in semi-auto so it probably took the X ground balance of Patch#1.  I did not try to go into Auto and leave out the ferrite.  Sorry, I was getting tired. 

 

54 minutes ago, Jonathan Porter said:

This is exactly what I’ve been warning people about all along.

 

Hey JP, I did check General/Difficult on Patch#1 and it was fine.  But on Path#2, it failed in HY/Normal.  I never got around to testing in Difficult. Typically, I can just go to General/Normal and be fine.

[Jonathan Porter]

The smaller coils should not be too bad for rub and bump noise, its usually the larger coils that suffer from this due to flex and movement in the windings.

The Ferrite balance problem is due to the coil not being correct electronically (could be any number of things) as such there will be a number of factors affecting the Ferrite balance and its outcome dependant on ground conditions. To check for saturation noise, ground balance the coil in Semi-Auto mode and then place the GB in Manual mode. Bring the coil to the ground and then place the coil directly on the ground (couple the coil to the ground), listen to the threshold as you do this, then pull the coil briskly up and away 8 to 10 inches and take note of the signal created as you couple and pull away, the louder this is the greater the saturation signal will be. You CANNOT ground balance out Saturation signal, you have to keep the coil just above it to avoid depth reducing noise.

Another way to Ferrite balance which might help in your instance is to place the Ferrite on a large rock 6 to 8 inches high and perform the Ferrite balance there, this might help to some extent.

JP

[goldenoldie]

Yes a smaller coil produces extra sensitivity for the tiny nuggets.

[phoenix]

Andyy I`m still pretty clueless as to which coil is which.   Is yours the spiral wound type or the DOD type? Dave