I purchased an F75 around two weeks ago. Yesterday I took off the Stock Coil and replaced it with a 5"DD Coil. Then I conducted several air tests before I went to a school to do some detecting. During these Air Tests as long as my Sensitivity was at least 30, I receive an Overload Signal Sound 100% of the time whenever a Nickel or a Gold Ring touched the Coil or was less than an inch from the Coil. If I lowered the Sensitivity to 29 or less no matter what process I used, I did not receive an Overload Signal when I placed a Nickel or Gold Ring up against the Coil or in very close proximity to it.
This Tip came in handy when I was detecting at the school while my Sensitivity was set at 60 because I received an Overload Signal Sound and Instead of walking away, I checked to see what had produced the Overload Signal Sound and sure enough, it was a Nickel located on top of the ground. Had I not tested conducted the Air Tests, before, I would have never have checked to see what was causing the Overload Signal Sound. Instead, I would have assumed it was a trashy target and walked away $.05 poorer or if the Nickel had been a Gold Ring, I would have ignored it as well possibly missing the find of a Life Time.
This Tip came in handy when I was detecting at the school while my Sensitivity was set at 60 because I received an Overload Signal Sound and Instead of walking away, I checked to see what had produced the Overload Signal Sound and sure enough, it was a Nickel located on top of the ground. Had I not tested conducted the Air Tests, before, I would have never have checked to see what was causing the Overload Signal Sound. Instead, I would have assumed it was a trashy target and walked away $.05 poorer or if the Nickel had been a Gold Ring, I would have ignored it as well possibly missing the find of a Life Time.