The chirping you describe when swinging the coil over the ground is very typical of any detector having the Ground Balance adjusted negative. Ground balance is a critical adjustment in that, if it is adjusted negative then the results will be excessive ground noise. If adjusted too positive then it will lose depth. The key issue you may be missing based upon your above post is that it is critical, is to be sure you have "first" found the ground balance point. In your post you indicated that you lowered your coil to the ground while in MGB and All Metal mode and the Threshold tone did not change or was perfect. Well, that may or may not be the ground balance point. It is very important to "first" find the point where the threshold tone makes a "change" (disappears or becomes louder) when lowing the coil within an inch or two from the ground. At this point you are very close to the ground balance point. A slight adjustment clockwise or counterclockwise will then find the balance point. Another, important step you didn't mention, is that it is also very critical to adjust the GB control slightly positive (about 1/8 to ¼ turn clockwise) after finding the ground balance point, then switch to the DISC mode. This is standard practice with most manual ground balance detectors to reduce ground noise. There are two other things that you may find helpful. Be absolutely sure the there is no metal in the ground near the place you are ground balancing and you will get better results if the Threshold volume is set very low, just to barely audible when ground balancing. Once you get the hang of manual ground balance it becomes as easy and natural as walking.

Now, there are occasions where the ground balance point can not be found due to specific ground conditions. When this happens, it is best to switch to FIXED GB to search.

Troy