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bigrex
01-26-2012, 07:22 PM
So, I took the Eureka Gold out for some hunting during the warmer months this year. I was experiencing the detector being very stable while in fixed mode and pretty erratic while in any tracking mode. I thought normally the opposite would be true since the tracking should eventually cancel out the ground changes. Has anyone else experienced this or do I need to send off the detector for a check-up? It seemed that I could not swing the coil very fast when using the tracking modes or the coil detector would begin making noises. That may have been related to coil cable movement, but with absolutely zero instability in fixed mode I wonder if that was the case. (Unless fixed mode is like cancel mode on a GP model Minelab PI detector, then I guess I would be losing a lot of depth in fixed mode, but I don't think fixed would be comparable to cancel mode).

Steve Herschbach
01-26-2012, 07:43 PM
I always run in fixed after letting a unit ground balance. Except maybe a White's GMT which is smoother in automatic. Hard to say you have a problem worth sending the detector in for. Just use what works.

Jim Hemmingway
01-26-2012, 09:04 PM
As Steve noted bigrex... it is hard to say what caused your instability without being on site with you.

From your description I don’t see any issue with your coil or cable, and likely not with your unit either. The answer may well lie with the ground you were searching.

For example, manmade iron rusts such that your tracking system sees it as the mineral it has become… maghemite. VLF metal detectors will track to some extent into rusted iron and will track fully into rusty deposits. This results in noise and instability while searching with the ground balance turned ON because the tracking system is bouncing up and down the GB scale trying to find the correct balance…but is never able to find it as you continue scanning. This causes the instability.

In these circumstances, find a spot clear of signals and ground balance to it. Then flip the control to the ‘fixed’ position and the unit’s stability should dramatically improve. Regularly recheck your ground balance to ensure you remain properly balanced when searching areas that cause this instability.

Now the above may not be the answer for you, but is worth keeping in mind. As a matter of habit, I always ground balance and then ‘lock’ my MXT to search. Rusted iron in the ground is the culprit in these parts.

Jim.

bigrex
01-26-2012, 09:34 PM
Hi thanks for the replies Steve and Jim, it just seemed totally erratic and would never settle down in tracking, while it seemed much less sensitive in fixed, but it also was a hundred times more quiet. This was in Nevada, probably on fairly mild ground. It should have been ground balanced, at least I did go through the motions of balancing it. If that sounds normal under some conditions I won't worry about it, I was just surprised by the difference between settings.

Jonathan Porter
01-27-2012, 12:05 PM
I always run in fixed after letting a unit ground balance. Except maybe a White's GMT which is smoother in automatic.

Steve I'm amazed you see it this way, my experiences are the exact opposite between the two units. I used to use my Eureka and the XT 17000 and 18000 in Tracking all the time.

One thing you have to watch with the Eureka Gold is to make sure you keep the coil near the ground when in Auto Ground Tracking, don't flap it about or the GB can go out very quickly especially if the ground is hot which will then cause the detector to sound noisy. The Minelab Automatic ground balance is in my opinion very good so long as you understand what it is doing and avoid the types of actions that will cause any auto GB to play up.

Just my 2c,

JP

Steve Herschbach
01-27-2012, 02:42 PM
Hi Jonathan,

Alaska low mineralization versus high mineral Oz - two entirely different situations. I almost never use automatic ground balancing of any sort here.

Jonathan Porter
01-28-2012, 10:36 AM
Hi Jonathan,

Alaska low mineralization versus high mineral Oz - two entirely different situations. I almost never use automatic ground balancing of any sort here.

Interesting Steve, and now your in the enviable position of having detected in both places so can easily speak from experience. I assume then the detector might be noisy because the GB is primed all the time due to the low amount of mineralisation, or more particularly the lack of variability of the mineralisation, therefore any sudden lifting of the coil away from the ground could throw the GB out instantly?

Regards

JP

Steve Herschbach
01-28-2012, 02:59 PM
Could be as I do not know where bigrex is - could be someplace with tough ground.

Reno Chris
01-28-2012, 06:34 PM
This was in Nevada, probably on fairly mild ground.

He lives in Utah I believe. I am guessing he may have been in the Rye Patch area. RP, while it is mostly very mild, does have hot spot areas of high mineralization in a few places.

bigrex
02-01-2012, 07:35 PM
Thanks for the additional replies everyone, Steve, Jonathan and Chris, I was actually testing it out in Osceola, NV I would say it was mild ground. I am in UT but have not really done any prospecting with it here. I had an XT18000 in the past and don't remember it acting quite like this, so I'll probably ship it off this spring or winter to the Chicago repair shop. I hope it does not turn out to be a hassle or horror story like a few I've read in the recent past. My only experience with repairs was shipping off a GP3000 once that burnt out when the power cord unscrewed while on. It was a reliable shop back then when in Las Vegas, or so it seemed. The noise appears to be pretty constant and matches each swing of the coil, it acts similarly in both slow and fast tracking.