Mike Hillis.....question on a previous post of yours "Have you figured out that the T2 has 2 levels of zero discrimination?"

Hi Mike,

A previous post of yours "Have you figured out that the T2 has 2 levels of zero discrimination?", you give instructions for achieving stable setups. My question is.......is the machine ground balanced prior to doing this procedure or after? And what type of balancing do you prefer with this procedure..Fast Grab or Manual?

Thanks

p.s. Would you post that article in its entirety on this forum



Edited 3 time(s). Last edit at 01/12/2011 02:49AM by TerraDigger.

I can't find that post? Sounds interesting.

It was from another website if I remember correctly, although the body of the procedure is on this forum under the post "Hey, I recognize that post! That's me!" If you do a search for it, remove the quotation marks.



Edited 3 time(s). Last edit at 01/12/2011 01:26AM by TerraDigger.

No worries, I found it. Wow that's an old post, I don't know if the same thing aplies to the newer T2 SE though.

Looks I have read that post before, and yes it would apply to the newer models.

Got the T2 this past December.......dying to use it.....and try Mike's procedure. Mineralization is pretty heavy in Idaho......the one time I got out for a couple of hours the machine was as chatty & unstable as a methhead..lol



Edited 1 time(s). Last edit at 01/12/2011 01:14AM by TerraDigger.

Idreamin3D Wrote:
-------------------------------------------------------
> No worries, I found it. Wow that's an old post, I
> don't know if the same thing aplies to the newer
> T2 SE though.


Can you copy/paste it here?

J

Here is the post Mike wrote:


This is important to understanding the T2.

Nearly all machines show the iron range as the very first conductive range on the discriminatory scale. Zero discrimination is acceptance of the iron range. There are machines with various degrees of iron acceptance, but the end result is the same; iron acceptance.

On the T2, the iron discriminatory range is 10-40. So a setting of 10 on the T2 is the same as a zero discriminatory setting we are familiar with on all other machines. This is the first zero discrimination level.

Unique to the T2 is the ability to go below iron into the mineral range, which is the 0-9 discriminatory settings. This can be technically considered to be a sub-zero disc range that is totally wide open and very susceptible to outside electrical effects as well as the internal noise of the T2 circuitry itself. This is the second zero discriminatory range. A discrimination setting of 0 on the T2 opens the T2 to receive any and all signals, including it's own circuitry noise. Once you understand this it becomes much easier to set up a stable T2 as regards to electrical interference.

This is how I am achieving stable setups:

With the coil held flat and unmoving on the ground, I select my primary tone id/target processing mode, then turn my sensitivity and discrimination settings both to zero.

I begin raising my sens setting until I start to just hear noise. I find that in my areas that it doesn't take much, usually somewhere around a sens setting of 15-25 before I start picking up electrical interference noise. I adjust my sens setting down a number or two so that the noise is barely coming through and at this point I run through the frequency selections to find the one that works best. I have found that doing the freq check at this level ensures that I am choosing the best one because I'm not overpowering the circuit, which in turn, lets me really hear which one works the best. If you can't tell as you cycle through them, then your sens level it too high and you need to back it down another number.

Once I've selected the quietest frequency, then I raise my discrimination setting to 10 (full iron acceptance or zero discrimination). Now I raise my sensitivity settings until I hear noise again and then back off a number or two until its quiet. I have now set my machine stable as far as electrical interference is concerned.

This easily lets me raise my sensitivity up into the high 70s, low 80's with no noise from electrical interference. Now, if the ground will let me, I can raise my disc up to around 25 and increase my sensitivity into the 90s and still remain stable. Thats IF the ground will let me.

The T2 is so sensitive to small and tiny targets (it is a gold machine after all) that the 'small signal' ground responses may force you to lower your sensitivity lower than required by electrical interference.

Switching to All metal mode, start with sens and hum level both at 0. Then raise the sens until you hear noise. Once you hear noise, raise your hum level until it runs steady and covers the noise. Then raise your sens level again until you hear noise. Then again raise your hum level until it 'hums' steady. I do this until I reach a hum level that I choose not to go beyond. For me, I typically stop when I reach a hum level of +3, which so far allow me to achieve higher sensitivity levels as regards to electrical interference. Then the ground always has the final say as to if I can keep it that high or not.

Remember. Electrical interference is adjusted to with a motionless coil. Ground interference is checked with coil in motion. If your detector is quiet when it is held still, you are not hearing electrical interference.

Hope this helps someone.

HH

Mike

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Edited 1 time(s). Last edit at 01/12/2011 04:38AM by TerraDigger.

Mike's way of doing it might work for his ground which is fairly mineralized in most areas. In low Fe ground some of that procedure can be bypassed IMO. Regarding checking and setting the sensivity and freq with the coil held motionless, myself and most people I know run the T2 as hot as possible. As long at there is no EMI present while sweeping the coil over the ground why not? It's kind of a pain to have it sounding off like R2D2 when you set it down to dig but the increased sens and audio volume on deeper targets is worth it.

Tom Z

I have the F-75 and have the same problem sometimes when I lay it down to dig, like Jackpine says it sounds like R2D2. The way I get around that is by pushing the off button on my Grey Ghost Ultimate Headphones..good feature to have on the headphones.

Hi TerraDigger,

I stabilize my detectors against the site's EMI before I ground balance. The site EMI determines what my maximum sensitivity level is going to be and then I ground cancel at that max sensitivity level. Make sense? Once that is done then I know that whatever audio I hear is either ground chatter or metal objects. If I get a lot of ground chatter that I find displeasing to my ears, or may hide the targets signals I'm after, I will re-adjust again to the ground as needed, either with a lower sensitivity level, or a gb offset or program change or some combination of the above.

Regarding ground cancelling via manual or ground grab, the targets I'm after determine how I ground balance. If I'm after the smallest target signals I manually ground cancel. If not, then I use the grab feature.

I no longer own a T2 or F75. My current detectors at the moment are the Fisher F5, the Fisher CZ3D (learning/on trial), Tesoro's Golden/Cleansweep combination, and ocassional use of my wife's Tesoro Compadre. However, my setup process still remains the same.

Responding to Jackpine's comment, some detectors (like the LTD model T2/F75, the F5, Tek Omega, and maybe others) now have a feature that uses the ground signal to help mitigate EMI responses. That means that they have two EMI stability points; one with the coil motionless (no ground signal mitigation applied) , and one with the coil in motion over the ground (with the ground signal mitigation applied). Which one to use would depend on ground minerals and the target signals you are after. For those with mild to moderate ground minerals there isn't much to consider, you'd do has he does and use the coil in motion settings. For those of us like myself with moderate to extreme ground minerals then it gets a little more complicated as the desired targets signals play a part in deciding how to stabilize to EMI.

HH
Mike

Thanks for taking the time to help us.

Good thread.