I'm new to the 17" coil, but like to use it with the harness for long periods. I've used it about 27 hours. Mine cannot be used to pinpoint in the same exact manner as the Coiltek 5x10" or Minelab 11". The 17 is much more sensitive on my soil, running in Auto +3. It overestimates depth more on foils and trash than good targets in my experience. And about 2""error on the good targets. I'm running in the standard coin mode, switching to all open in that I want to get used to all that's there in my trashy farm yard area and creek.
The wider coil arms give 2-4 bleeps as I sweep across a good target. As the center bar crosses, it sounds like a clear Bleep with a lower echo closely following. If I sweep fast these two sounds blend into one, not quite right, Bleep for the center. At the widest, the Bleep sounds before the target is crossed by the outside coil rim. It's as though the outside beam is tilted inward so the sound hits at about 2/3 distance from the center bar to the outside bar.
As I back up over the target, the outside Bleeps start to coincide with the outside bar. At the forward tips and notch, the Bleeps are clearest, and I can be certain of pinpointing when I have the object sounding as I gently move the notch forward, and check that by a tiny side to side where the target Bleeps on the two forward coil points. Note that this pinpointing will indicate somewhat forward of the target's true position.
Using the machine's pinpoint function tends to to leave me to the right or left and forward of the true location.
In Summary: when a good Target pops up, I first try to put it on the center bar by using short lateral strokes, stopping after each move, and listening for the "close double bleep" or "Echoed Bleep" . The lower, quieter bleep is on the same side of the target as is the center coil. Most of the time, going back the other way will give the same "Echoed Bleep" with the quieter bleep again on the same side of the target as the center bar. Then just slowly, shortly, wiggle side to side until you've moved the Signal to the coil tip and it quits. Now you know you're ready put the target in the front notch of the coil. This puts me just a bit forward of the true target. The deeper the target, the more forward of its true location will the coil notch be.
So think of the 17" as a severely angled, cone shaped beam more than the blade like beam of the 11" and CoilTek 10x5" coils and you'll learn to pinpoint reliably. Or think of it as TWO ANGLED, Parabolic, blade-shaped beams ( like a curved bottomed boat) wherein you can pinpoint on either blade in the middle or both coinciding blades on the forward points.
This is just based upon my using the 17", not upon my knowing any detailed engineering principles...
The wider coil arms give 2-4 bleeps as I sweep across a good target. As the center bar crosses, it sounds like a clear Bleep with a lower echo closely following. If I sweep fast these two sounds blend into one, not quite right, Bleep for the center. At the widest, the Bleep sounds before the target is crossed by the outside coil rim. It's as though the outside beam is tilted inward so the sound hits at about 2/3 distance from the center bar to the outside bar.
As I back up over the target, the outside Bleeps start to coincide with the outside bar. At the forward tips and notch, the Bleeps are clearest, and I can be certain of pinpointing when I have the object sounding as I gently move the notch forward, and check that by a tiny side to side where the target Bleeps on the two forward coil points. Note that this pinpointing will indicate somewhat forward of the target's true position.
Using the machine's pinpoint function tends to to leave me to the right or left and forward of the true location.
In Summary: when a good Target pops up, I first try to put it on the center bar by using short lateral strokes, stopping after each move, and listening for the "close double bleep" or "Echoed Bleep" . The lower, quieter bleep is on the same side of the target as is the center coil. Most of the time, going back the other way will give the same "Echoed Bleep" with the quieter bleep again on the same side of the target as the center bar. Then just slowly, shortly, wiggle side to side until you've moved the Signal to the coil tip and it quits. Now you know you're ready put the target in the front notch of the coil. This puts me just a bit forward of the true target. The deeper the target, the more forward of its true location will the coil notch be.
So think of the 17" as a severely angled, cone shaped beam more than the blade like beam of the 11" and CoilTek 10x5" coils and you'll learn to pinpoint reliably. Or think of it as TWO ANGLED, Parabolic, blade-shaped beams ( like a curved bottomed boat) wherein you can pinpoint on either blade in the middle or both coinciding blades on the forward points.
This is just based upon my using the 17", not upon my knowing any detailed engineering principles...