I got out this morning to do a review on a new Russian10" Xcoil that I received for the GPZ. 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 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 on this coil. I will let you know if I find out anything further.
(gold sizes in grams: .05/.07/.08/.21/.19/.71 = 1.3g)