White’s Electronics TDI - Manual (Page 23)

PulseScan TDI Owner’s Guide 
GROUND BALANCE - KNOB
What it does
This control adjusts or balances the interference from ground mineralization. It is
only operative when the Ground Balance toggle switch is in the On position.
How to use it
To ground balance Pulsescan TDI, the search coil is pumped slowly up and down
from one inch near the ground to 6 or 8 inches above the ground while listening
for a change in sound.
This process must be done with the Target Conduc-
tivity control set to All.
Start this process with the Gnd Bal Control set at 6 (12 O’ clock). Begin pump-
ing the coil slowly up and down toward the ground. You will hear the high tone of
low-conductive metal as you approach the ground. Now start turning the Ground
Balance 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, and 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, but start to turn the ground balance knob
back counter clockwise until you enter the quiet zone again. This area of quiet