White’s Electronics TDI - Manual (Page 24)

4 PulseScan TDI Owner’s Guide
where you hear only the faint hum of the threshold is where the Pulsescan TDI is
balanced to the ground. You will have to turn the knob very slowly in very small
increments to reach the most exacting point for eliminating ground minerals. At
this point, you will most likely notice that the Ground Balance knob is usually
between 8 and 9 on the scale.
If you change the setting on the Gain or the Pulse Delay, you should adjust the
Ground Balance setting if needed. In addition, if you begin to hear ground noises
(false signals) you should also adjust the ground balance. Of course, the Gnd
Bal toggle must be On to use the Gnd Bal control.
If the Pulsescan TDI does not require ground balancing, there is another
option. The Pulsescan TDI can be operated as a standard pulse detector with no
variable audio by switching the Gnd Bal toggle OFF. All targets will now sound
the same. The upside of this is that the detector will detect deeper. Downside is
you dig everything.
If the Pulsescan does achieve ground balance, the Gnd Bal toggle must be
kept On, and both Gnd Bal and the Variable Audio feature will be active. This
situation indicates that there is enough iron mineralization to balance.