705 ground balance questions, am I doing it right? If not, how does it affect the operation?

[hotrod53]

My last detector had a manual ground balance, I had to pump the coil up and down like the Xterra while I manually adjusted it. As I adjusted the knob up or down the tone would change, I kept adjusting until the tone was even as I pumped it. Based on my Xterra manual, it sounds like this is the same idea. I do however notice the Xterra doing a woo... woo...woo as I pump the coil up and down, then the AU finishes, I never hear it equalize. As I sit here and think about this, I'm wondering if I am going into ground balance while my coil is on the ground instead of enabling it while it's elevated the 4". If that is correct, will that whack out my ground balance? Should the tone become more equal as I pump it up and down or is the up and down woo...woo normal? BTW, I am trying to find a spot without targets when I balance and I do it in AM. I don't know if it's just the PA ground, but that is really hard to find a spot with no signal.

On my other machine, if the ground balance was not accurate, the ID would be offset. Does the Xterra 705 do the same?

 

[7centsworth]

Check out the faq faq post at top of page there are some videos and all kinds of information up there.

 

[SeniorSeeker]

Minelab X-terra 705 Instruction Manual It take a few minutes to upload the file, so be patient.

 

[hotrod53]

I have the manual and I have read it over and over, it really doesn't answer my question, I guess that I need to experiment. When I read about manual ground balance, it sounds like what I am familiar with. They mention hitting + and - to "aim for a minimum volume and the transition between low tone and high tone". Minimum volume during GB is new to me but high to low tone is familiar. I can do a manual balance if need be, I do recall hearing no tone and then tone as I pump the coil up and down in auto. I guess I need to pay more attention to volume and change of tone to figure out if this is correct.

The manual also does not address my question regarding ID offset with incorrect ground balance.

 

[Digger]

Ground Balance a form of discrimination in that it allows you to adjust the ground phase of your detector to compensate for the mineralization. The procedure requires basically the same "bobbing" motion for both manual and Auto GB. Just don't let the coil touch the ground on the "down stroke". When using manual GB.........as the coil is on the "down stroke", you will hear a change of tone. If it is a low pitch tone, the current GB setting is numerically lower than the site requires. I you get a high pitch tone on the "down stroke", decrease the ground phase setting by pressing the - pad. Continue to bob the coil and make the + or - changes until you get a setting that has the least pitch variation when lowering the coil.

In AutoGB, press the Ground Balance pad, press the Mode pad, and then bob the coil as described above. The letters AU will appear on the display, and within a few seconds, your X-TERRA will have set the ground balance for you, by using the software parameters of the X-TERRA. With that said, I have used Auto GB while suspending the coil about an inch above the ground and found that the ground phase setting varies little from when I bob it up and down.

A more simple method (and the most accurate) on the X-70 and 705 is to run in Tracking mode. After a few sweeps of the coil, you can check the setting by pressing the GB pad. The X-TERRA will display the ground phase reading for the soil under the coil at that precise moment. Press it again and tracking resumes. If you turn tracking off, the ground phase will continue with the latest "update" performed by the tracking function.

If you've set your ground phase and are concerned it may not be "accurate" (at any given time), it might be best to keep the tracking turned on. One word of caution would be to deactivate the tracking mode when X-ing over a target. Otherwise, if you continue to sweep back and forht over the same target, the X-TERRA may interpret the target to be part of the ground matrix. As I said, GB isa form of discrimination.

I usually run my X-TERRAs with a 3-point postive offset. I've not found an appreciable difference in TID. JMHO HH Randy

 

[hotrod53]

Digger, so if I understand correctly, here is how I see it: hearing a tone is normal and it may not always be the same tone, that tone will relate to whatever is in the ground. That tone can also be louder or quieter depending on how much mineralization is in the ground. The detector is, for lack of a better word, syncing with the ground minerals and sounding off the associated tone. Hearing the tone is the detector matching the ground minerals and the tone being steady means that it has locked on. If the tone was changing, that indicates an incorrect GB. Once the AU goes away, the detector has masked that tone particular, correct? By using the AUTO tracking, the detector somehow sends out an occasional test signal, and then masks that response. By trying to pinpoint while in tracking, the detector locks on to that target and therefore tries to mask it.

 

[Digger]

Pretty close. But the tone you hear with the coil in the air won't change until you lower it toward the ground. When you change the ground phase, by pressing either + or -, the tone will either get higher or lower pitched (depending on the mineralization and the current ground phase setting on your X-TERRA) as you lower the coil. Not necessarily louder or quieter, although it may seem that way if it is way off to beging with. Once you get the tone so it maintains the same pitch as the coil gets closer to the ground, it is about as well balanced as you can do it, manually. Auto GB provides a much more accurate ground balance than what we can do by listening, performing a manual GB. One other thing......it isn't Pinpointing mode that will cause the masking. It is X-ing over the target while in Tracking. When you switch to Pinpoint, Tracking is "disconnected" until you get out of Pinpoint mode. HH Randy

 

[cambo62]

Hi guys. I'm a newby to this and have a question about the ground balance on the 705. In all metal and after doing the noise cancelling, I can do an auto GB in the same spot and get different results say 34 then 42 only seconds apart. I'm being careful not to touch the ground and not near any targets. This is on my front lawn about 5 metres from the house.
Is this normal.
I'm using the stock 7.5kh concentric coil.

Thanks for any comments.

 

[BH_Landstar_]

With the X-Terra 705 you don't need to GB the unit if you have AUTO TRACKING on, the detector will do it on the fly as soon as you start to sweep the ground, thats the beauty of the X-Terra 705.

The noise cancel channel is the only one that will need to be set using the AUTO detect method before you start to sweep the ground.