Hot ground

[sport.pilot]

Still learning the X-70, and I am wondering what ground balance number indicates that I am detecting in hot ground? Also, are sensitivity settings and hot ground balance numbers inversly related - or put another way, when the gound balance numbers indicate I am in hotter ground, should I generally lower my sensivity settings? If so, can anybody give me a guide as to what settings are good in general for hot ground and what I should use when the ground is not. I hunt in the AM mode always, and usually do not use tracking unless I notice that the GB numbers are jumping around in the areas I am hunting. I mainly hunt city parks for coins and in the AZ desert for gold nuggets and meteorites. Thanks.

 

[Digger]

Simply put, ground balancing a detector as the simplest form of discrimination in that you are discriminating out the adverse effects of the ground. When you have a properly ground balanced X-70, highly mineralized sites will cause a smaller number to be displayed while in the GB mode. Inversely, higher GB numbers represent lower soil mineralization. Although I've not read anything "cast in stone" about hot ground or cold ground, over the past couple years I've been using the number 28 as my point of reference, for coil selection. If I can GB a concentric coil, with a GB number of 28 or higher, I believe my concentrics will do an effective job. However, if the ground is what you referred to as "hot", and the GB number is less than 28, I believe I get better performance with a DD coil.

In theory, if you set your ground balance to "neutralize" the effects of the soil, then your sensitivity shouldn't vary dramatically between sites. And even if it did, telling someone else where to set their sensitivity is virtually impossible. It would be like me telling you when to run with your headlights on bright, compared to how much fog neccesiates low beams. As to sensitivity on my X-Terra, I run a bit higher than others might. Most sites I hunt allow me to run with it in the upper 20's. When I am running high sensitivity, if I bump the coil into a clod, it might cause a false signal. If I raise the coil at the end of a sweep, it may false. If I get sweeping too fast and there are a lot of trash targets, it will false. Not enough to make me stop and dig a ghost. But enough to let me know I am running with as much sensitivity as I dare. I've learned to accept a fair amount of chatter, and know what makes it happen. If I start getting constant feedback from the coil other than from something I caused, then either my GB is out of whack, or I need to lower the sensitivity and slow down my hunt.

I'm not sure where you see the GB numbers bouncing around. GB numbers will not appear when you are in a hunt mode. As to tracking......if there are fewer than two or three targets per sweep, and the mineralization varies a lot, I'll use the tracking mode. However, if the soil is consistent, and the targets are close together, I will usually keep it in C/T , check it every few minutes, and make adjustments accordingly. JMHO HH Randy

 

[sport.pilot]

Randy,
Thanks for the reply and explanation. I notice the change in ground balance numbers because after years of hunting for gold nuggets with my Gold Bug 2, I ground balance my detectors fairly regularly (a habit now that is hard to shake) to be sure that I am in a slightly positive balance. So, this habit has carried over into my coin hunting as well, and when I balance, I notice that the soil might vary from say 33 in one part of a sport field to 47 in another. I hunted a park a few weeks ago, and noted that most of the numbers were in the low to mid 20s, thus my question as to what number one might use as a guide for viewing ground as hot or not, I wanted to know this to determine if I should be using a DD coil or not when hunting in these large open sports fields that are usually low target environments. Thank you again much for your help.
Darryl

 

[kansas]

One of the ongoing common mis-conceptions is that the Ground Phase Number(Ground Balance)represents how much mineralization a particular soil matrix contains. The mineralization of course referring to minerals that cause poorer performance of a metal detector, and not a particular quantity of an inert material.

The Minelab X-Terra X-70 has a hidden feature which allows you to make a reasonably accurate assessment of your ground conditions including the iron(Fe3O4, black sand) and/or the conductivity(salinity) of your soil. To clarify, you can quickly measure in relative terms how magnetic or conductive your ground is. You can then jot those numbers down and compare them to any other X70 users in the world.

As a matter of fact a database or registry could be set up to compare your conditions to that of others. Therefore when an X70 user states that they have "high mineralization" which is hampering operation, it can easily be verified whether such is the case.

The procedure is really just an extension of Auto-GBing the X70. So don't become overly concerned that it is terribly complicated, it isn't.

Procedure in Normal GB mode with GB Tracking "OFF" and Sens=20:

A. Auto-noise cancel in the area you will hunting with the coil held 3 feet above the ground and parallel to it.

B. Locate a target free area of soil.

C. Engage Normal GB & remain in the GB screen.

D. Place coil on the soil. Do not press the coil against the ground! This will distort the coil shape and give an inaccurate result. Simply allow the weight of the machine to lightly keep it against the ground.

E. Press the Auto GB button and raise coil about two feet above the ground before Auto GB has completed. If by the time you reach the apex of pulling the coil up to two feet it doesn't complete, then pump up and down from just above the ground to two feet high as accurately as possible. Recall that Auto GB signals with a tone when completed.

F. While still in GB mode press and hold Patterns button to get the numbers. The numbers are six digits in length but read out in three groups of two that will repeat if the Patterns button is held down. Therefore 99 99 99(almost a million) is the largest number possible and 0(00 00 00) is the smallest. Forty-six thousand would appear as the following sequence, 04--60--00. Make a note of the numbers which we will call the "IRON NUMBER"(Magnetite...Black-Sand).

G. As a reference, numbers in the thousands are mild ground, medium grounds tens of thousands , and hot hundreds of thousands. For clarity:

1. 0(zero) >> 10K mild ground.
2. 10K >> 100K medium ground.
3. 100K >> 1M hot to scorching.

Procedure in Beach GB mode with GB Tracking "OFF":

The same as above in normal GB except that your are measuring conductivity. Great for Ocean beaches, salt flats, & dried up lake beds etc. I would also take three samples in the exact same spot and average them to get an average number, using either of the above procedures.

If their is enough interest, then a registry could be started to compare the various ground reports with how stable the detector runs, and effect on depth, correct ID etc. The nine inch default concentric MF should be the only coil used to take the measurements to create a standard. Keep in mind that the X70 may be able to show you why other detectors you own behave in a certain manner based on soil mineralization. It may also provide pertinent information about what equipment you should consider for future purchases.



HH
BarnacleBill

 

[sport.pilot]

Wow. That is way cool. I will have to try that when I am out hunting for gold nuggets too. That way I can determine if I need my DD coil or I can hunt with the concentric coil on my X-70 and or my GP Extreme. I am also going to do it at the local parks I hunt. Thank you very much!