I apologize if this has been asked, i did a search couldn't find exactly what i was looking for-I have a new AT Pro with both the stock 8.5X11 and the 5X8 DD coils. What kind of depth are you all getting with these coils? I laid a 1961 Franklin half dollar in the ground at 6", and barely get a reading with the large coil, no reading with the smaller coil........running pro-zero, sensitivity maxed, ground balanced. The signal on the large coil is "choppy" at best like there is iron in the hole with coin, but I checked the area thoroughly before I planted the coin. I also changed batteries, re-wrapped the coil cable correctly and removed then re-inserted the coil connector.........at 6" I would think the large coil would "chirp", and the small coil would produce something............again, its a new unit from a sponsor on this site.........suggestions?
At Pro Coil Depths
- Thread starter slvrsrchr
- Start date
Well, I never found a half at 6" so I cannot say for sure.
One thing I do know is that coins freshly planted, and coins which have been in the ground for a while sound different.
something about a halo effect.
One thing I do know is that coins freshly planted, and coins which have been in the ground for a while sound different.
something about a halo effect.
MadTownScoop
Elite Member
^^^ What he said. There is some truth to the "halo" You can sometimes notice it after you have retrieved your coin and put the pointer back in the hole. It will sometimes act a little chirpy like there might still be something there. My AT-Pro 11x8 coil? Best was about 11" but that was a 1900 Quarter in wet sand, Fresh water. Best with 5x8 coil?? I'd have to say around 5-6". Best so far with my 17" NEL coil. Bout the same as the 11x8 coil. Just have not hit a truly deep object with it I guess.
BensJamming
Senior Member
Been using the 5x8 more but have pulled a buffalo nickel at all of 8+ inches the other day, a mercury dime at a good 7 inches, a license plate at about 18 inches, german silver womens essentails case at like 12 to 14 inches, pennies down at 8 to 9 inches..... Most amazing (to me anyhow) was the 22 bullet (just the lead) down a good 9 to 10 inches, and it rang in nice and clear. The only half dollar we found was a 71 and it was about 5 to 6 inches but was a super clear, loud, and like 87ish on the VDI rock steady.
I think the fact they were freshly buried had a lot to do with it. Also did you properly GB it? Seems like that make a big difference, and be sure to do a reset each time you change the coil. I also reset everytime I switch the batteries or if it start acting up from EMI or something.
I will have to try freshly burying it again in the yard and see what depths I can get sometime.
I think the fact they were freshly buried had a lot to do with it. Also did you properly GB it? Seems like that make a big difference, and be sure to do a reset each time you change the coil. I also reset everytime I switch the batteries or if it start acting up from EMI or something.
I will have to try freshly burying it again in the yard and see what depths I can get sometime.
BentRod
Elite Member
What's your auto GB numbers? Here in WA I'm in the low 90's. I've yet to find a coin (clad or silver) over ~6". Most are coming in between 3"-5". I think the highly ferrous mineralized soil we have here really negatively impacts the depth capability of the ATP. Of course I've only been using it for a few months now, but have found quite a few clad coins and a good number of silver dimes thus far. I too have used both the 5x8 and the 8.5x11 coil. I'm currently running the stock coil and 5"-6" is still as deep as I'm hitting on the silver dimes. FWIW.
BensJamming
Senior Member
Have never auto GBed below 84. Usually around 88-92. One spot we hunt is always 86 though it seems like.
Sent from a hidden menu within my AT Pro
Sent from a hidden menu within my AT Pro
Mntnclmbr
Forum Supporter
Soil and moisture make a huge difference. Found a Mercury dime a good 9" in damp sand next to a lake. (It was black do to the long exposure and possibly soil).
Can't say as I have done any testing on planted coins. Too busy lookin for preplanted coins
Can't say as I have done any testing on planted coins. Too busy lookin for preplanted coins
Grumpysrb
Forum Supporter
I use both coils. I get about 2 or 3 more inches with the 8.5x11(a Penney at 10 inches) over the 5x8(a Penney at 6 to 8 inches). You can adjust your ground balance manually to get a slight increase in depth. My machine GB's in the 80's.
Txdirtfisher
Forum Supporter
Sounds Like a Ground balance problem also Try doing a Factory reset as well . Halo or no halo effect it should respond to a Buried half dollar either coil . Make sure it is ground balanced and sensitivity as well as disc ic is correct
Thank you all for the responses. I am currently ground balancing at 88, after I swapped coils I did do a full reset on the machine and GB again. Im going to pull out the Fisher F4 I have with 11" dd coil, go find a nice sold target somewhere in the yard and then try with the AT Pro (this should avoid the planted coin halo effect issue). Ill let you know what I come up with. A few other things Ill try is to negative GB a few points (worth a shot), and back off sens. a notch or two. Again, thanks for the replies.
Brainworm
Elite Member
Give Garrett a call and tell them your situation. A Franklin half dollar in the ground at 6 inchs should be giving you a nice solid high tone with either coil.
sent Garrett an email describing the situation, raining cats and dogs right now, will try to compare with the F4 tomorrow, that is unless we get snow like the forecast is saying.....ugh! Really appreciate everyone's responses so far.
