Big/little coil & GB?

[WV62]

I have notice when hunting an area with the F75 that if I change coils and do another GB I get a different GB number. So is it the coils or the nearby trash in the ground? With the 11" coil I will find a so called clean spot and GB at about 68 to 72, with the little 5" coil I will go to the same area and GB in the high 40's and into the 50’s.
Any thoughts on this?
Ron in WV

 

[Charlie P. (NY)]

The coil averages everything below (and above) it to come up with a ground balance number. The bigger coil is seeing more soil, and slightly deeper, so it isn't surprising the number is a bit different.

It's just a relative number at best, anyway.

 

[shadowulf]

Smaller footprint, less exposure to ground mineralization .
Large footprint, more exposure.

Same idea why smaller coils do better in trashy areas. They aren't seeing as big an area as a larger coil.

At least that's how I think of it.

 

[jim tn]

Yeah, thats how I see it as well. Bigger coils see more verses the smaller. Ron, my small coil g b's less then the 11", but not quite as drastic as yours. Typical g b on my 11" is around 68-72. 5", 62-64. HH jim tn

 

[shadowulf]

Yeah, thats how I see it as well. Bigger coils see more verses the smaller. Ron, my small coil g b's less then the 11", but not quite as drastic as yours. Typical g b on my 11" is around 68-72. 5", 62-64. HH jim tn

Same here in my western soils. I will put on the 6.5 coil when the 10x5 is having a hard time balancing or is running really high numbers. I can "gain" about 5-7 lower points on ground balance. Not sure if it really helps. But it does stabilize better at higher sensitivity, so it makes searching a little easier on the ears.

 

[Elton]

I just had a recent purchase detector that showed the GB changes as you covered the ground. Numbers and a blacked out area on the screen I was amazed at the difference in just a few feet.. I liked that feature and the machine changed the GB to match the ground as I went along.. In some areas it was minor, and in some it was pretty drastic to be honest. Way more that I thought, or was always lead to believe by manufacturers. In your coal laden ground you might be surprised at the changes in GB no matter the coil as you swing along..

Like I said I was pretty surprised to see some of the drastic changes in short distances.. The 5" always changed less than the bigger coil did too

 

[conehead]

One thing I have noticed that is kind of different, when I switch to my 13" Ultimate coil is it will sometimes ground balance to a lower number than the stock 7X11 coil on my Omega.
Plus I'll say the Ultimate coil runs smooth for such a large coil.

 

[WV62]

So it looks like the ground has it.

Thanks all for the input,

Ron in WV