Gamma 6000 ground balancing

[auximenes]

When I go to set up my machine at a new site I often have trouble getting the ground balance set. I know that I won't be able to do it above a piece of metal so I normally put it in 'All Metals' mode to sweep around for a clean spot. Then, even at a spot that seems to be clear of metal, the machine wants to ground balance below 40 which of course doesn't work. I start with the machine about 6" off the ground as per the manual and then move it down and pump it an inch or so off the ground. Even before lowering the coil it often just buzzes. Am I missing something? Is the soil around here on the west coast of Florida that full of trace iron?

 

[cal]

Generally on ground balances that are below 40, I set the ground balance manually on 40 or low 40's, then hunt. I only adjust out of this setting when I notice a medium or high ground indicator. Hope this helps.

 

[auximenes]

the machine wants to ground balance below 40 which of course doesn't work

For clarity, I should have said 'auto-ground balance'. You can of course manually set it to lower than 40.

 

[auximenes]

oops, please disregard, didn't mean to post another reply

 

[Monte]

When I go to set up my machine at a new site I often have trouble getting the ground balance set. I know that I won't be able to do it above a piece of metal so I normally put it in 'All Metals' mode to sweep around for a clean spot.

That's the right thing to do ... find a clean, metal-free spot of ground.

Then, even at a spot that seems to be clear of metal, the machine wants to ground balance below 40 which of course doesn't work.

That's possible if the ground mineral content is very low. The manual suggests '40' or below but I found that to be true from about '50'ish and below. Since you're in Florida on its West Coast, I am sure you're dealing with very low ground mineral content.

I start with the machine about 6" off the ground as per the manual and then move it down and pump it an inch or so off the ground.

That's the wrong thing to do. Actually both things are wrong. Forget what the manuals say about starting with the search coil at 6". You can do that with some competitive brands, but the Teknetics models, and similar Fisher models, need to have the search coil on the ground before you activate the Ground Grab touchpad. The reason? It needs to have some signal information [size=small](the ground signal)[/size] to start with.

Then, the search coil needs to be briskly lifted away from the ground [size=small](after pressing the Ground Grab touchpad)[/size] to about 6" to 8" and quickly lowered back to about

 

[auximenes]

OK, I was out again for a few hours today and got the auto-balance to work as I remembered. I guess I'd got the technique mixed-up somewhere along the line. Thanks for the corrections Monte.

So, the follow-up question is, after setting the ground balance, the machine reading was really jumping around at the default sensitivity of 80. The ground at the site was definitely heartily sprinkled with iron trash so I figured that's what was causing the machine to bounce around so much. I turned the sensitivity down to 70 (and 65 briefly) and that seemed to stabilize it. Now, am I missing or overlooking something again here? Was my assumption on the ground condition and its effects inaccurate?