Not sure the significates

[Mark-VA]

Been hunting with GB at 0 to better eliminate nails, but at a great reduction of detection depth.
Noticed the deeper silver in my test garden were not detectable.
With GB at 0 a silver dollar is not detectable unless rubbing bottom of coil.
So I had to perform air test.

Normal GB of 7-8 air test would give a good audio response of a nickel and gold ring at 13", and silver dime at about 12"

GB of 0 and the nickel and gold ring would respond at about 7" and the dime at 6"
At GB of 0 a silver dollar is not detectable at 2".
Increase pulse to max and the silver dollar will respond at 5-6" with GB of 0.
Been wondering if my GB was function correctly.

But turning ground balance off, the SL will give a good response on all coins and rings to about 13"

Seems like something might be wrong.

[Funfinder]

Your coil might be got de-tuned, some cap inside with lose contact etc.

What you are describing is typically for GB-contrast-factor -
if you set it to iron / high mineralized, the sensitivity for silver and alu will decrease.

[greylourie]

Reg Sniff does a sterling job of explaining how it works here. http://www.findmall.com/read.php?73,1910809

Funfinder, Mark is talking about his TDI SL. So no cap in coil.

[Carl-NC]

Been hunting with GB at 0 to better eliminate nails, but at a great reduction of detection depth.
Noticed the deeper silver in my test garden were not detectable.
With GB at 0 a silver dollar is not detectable unless rubbing bottom of coil.
So I had to perform air test.

Normal GB of 7-8 air test would give a good audio response of a nickel and gold ring at 13", and silver dime at about 12"

GB of 0 and the nickel and gold ring would respond at about 7" and the dime at 6"
At GB of 0 a silver dollar is not detectable at 2".
Increase pulse to max and the silver dollar will respond at 5-6" with GB of 0.
Been wondering if my GB was function correctly.

But turning ground balance off, the SL will give a good response on all coins and rings to about 13"

Seems like something might be wrong.

This is normal. You've hit the GB point for the dollar, so it nulls. If you could adjust the GB a little further, the dollar would start responding as a low conductor (high tone).

[Mark-VA]

Thanks Carl.
I did visit the test garden again this afternoon and this is what I found.
I have a quarter and dime buried at 6 1/2" deep.
There is also a buried nail several inches from the quarter.
May goal was to set the machine to where the nail would not respond but the quarter and dime would give a good audio response, but I could never accomplish this.
At 0 GB the quarter and dime would only give an audio report about half the time and the nail was silent.
Turn up the GB slightly and the nail would report, with no change in the quarter and dime.
increase the pulse delay and the same results, nail gave an audio and the quarter and dime only about half the time.
The only way to get the quarter and dime to give a good report was to increase the GB to around 4.