QED PL3 Owner's Manual page 38

QED Setup Procedure
The next steps are dependent on the coil chosen and what you are going to
detect.
Small coil/mullock heaps
1. Drop THS-B until the QED gets noisy, then back up until quiet
(probably around 6 under NULL)
2. Increase Gain until noisy, then back down until quiet (or to a point
where you are happy with the threshold).
3. Detect very slowly
Small coil/general detecting
1. Same as above, or
2. Raise THS-A to a point where it gets noisy, then back down until
quiet
3. Lower THS-B from NULL until the QED gets noisy, then back up until
quiet (probably around 1/2 under NULL)
4. Increase Gain until noisy, then back down until quiet (or to a point
where you are happy with the threshold) - try to hold the highest
possible gain. I generally am able to use a gain of 6 (or thereabouts)
in the Vic GT, even higher with the x-coil.
Medium to (small) large coils - shallowish ground
1. Raise THS-A to a very high (75/85) point until it gets noisy, then back
down until quiet - try to hold the highest possible THS-A.
2. Set THS-B to NULL or lower THS-B until the QED gets noisy, then
back up until quiet (probably around 1/2 under NULL).
3. Increase Gain until noisy, then back down until quiet (or to a point
where you are happy with the threshold) - try to hold the highest
possible gain.
38