White’s Electronics TDI Pro - Manual (Page 21)

TDI Pro Owner’s Guide 21
of their range (12 O’ clock). Begin pumping the search coil slowly up and
down 1-6 inches from the ground. You will hear the high tone of low-con-
ductive metal as you approach the ground. Start turning the COARSE
knob slowly clockwise as you continue this pumping process. The high
tone will usually continue with each pump toward the ground for a short
period of time, and then start to fade to no tone other than the threshold
hum.
Continue the process of pumping slowly, turning the knob clockwise past
the quiet zone. You will begin to hear the low tone as you approach the
ground. If the ground has moderate mineralization you may not hear the
low tone.
At this point, continue with the pumping process (1-6 inches from the
ground), and start turning the COARSE knob back counter clockwise
until you near the quiet zone again. NOW switch to the FINE control and
fi ne tune for as little change in Threshold as possible while pumping the
search coil 1-6 inches over the ground.
This area of quiet, where you hear only the faint hum of the threshold, is
where the Pulsescan TDI Pro is balanced to ignore the ground. You will
have to turn the knobs very slowly in very small increments to reach the
most exacting point for eliminating ground minerals. Once close, switch-
ing to the FINE control eases this process most obviously in extreme
ground mineralization. At this point, you will most typically notice that the
COARSE knob is between 8 and 9 on the scale. However, the position
is not important. What is important is being able to pump the search coil
1-6 inches over the ground with no change in Threshold, indicating the
Pulsescan TDI Pro doesn’t see the ground.
If you change the Gain or Pulse Delay, you should re-check and re-adjust
the Ground Balance setting as needed. Often only FINE control adjust-
ments are necessary after the initial COARSE setting. In addition, if you
begin to hear ground noises (false signals) you should also re-adjust the