I discovered a neat tip to share with others while detecting with your F75. Because this guy is SO sensitive, if you are in an area with an increased amount of interference (indicated by high-tone chatter), lower your sensitivity. I've found this lowers the volume of the high-tone chatter and allows you to hear the real high-tones more clearly as they will remain at a somewhat similar volume to the higher sensitivity setting. I went over an area with a high sens and found nothing, then went over the same area with a lower sensitivity, and found a bunch of coins including a stack of 3 silver dimes. The previous high-volume, high-tone chatter hid the signals where as the low-volume, high-tone chatter did not.
Also, I've noticed a much clearer distinction between the high-tone chatter due to interference and real signals if I'm touching / rubbing the ground when swinging. It takes a bit more effort because you have to deal with the friction of swinging with your coil touching / rubbing the ground, but you'll find the more plentiful and clear targets worth the extra elbow grease.
Also, I've noticed a much clearer distinction between the high-tone chatter due to interference and real signals if I'm touching / rubbing the ground when swinging. It takes a bit more effort because you have to deal with the friction of swinging with your coil touching / rubbing the ground, but you'll find the more plentiful and clear targets worth the extra elbow grease.