Adjust THRESHOLD
To adjust the threshold tone, turn the THRESHOLD knob clockwise until you hear a slight but
steady tone. You may have to turn the knob to somewhere between the 1 o’clock and 3 o’clock
position to get the best hum. Please remember that the threshold only affects the all metal mode.
The purpose of the threshold tone is to give a reference to judge targets for pinpointing and to
adjust the ground balance. (For more information on ground balancing, see the
“Adjust Ground
Balance for Air Test”
section on the next page and the
“Ground Balancing in the Field”
section.)
In the field, some targets may be small enough or deep enough that they will not be able to
generate an audio signal by themselves. By monitoring a threshold tone, you already have a
slight audio tone so changes are easier to hear. However, if your threshold tone is set too soft or
too loud, small changes in the signal will be hard to hear. Take some time and find a threshold
level that is right for you.
Adjust THRESHOLD
The ground balance function for your Tejón is a form of discrimination that allows you to tune
out the mineralization in the ground that may mask targets or decrease the detector’s depth and
sensitivity. The GROUND ADJUST knob is on a 3 and ¾-turn potentiometer. While the knob
will turn endlessly in either direction, when the potentiometer is at the end of its range, a slight
drag may be felt.
Note: The following procedure is for the air test only. For directions on ground balancing
your Tejón in the field, see the “Ground Balancing in the Field” section on page 16. For the
best performance of your Tejón in the field, the machine must be ground balanced to the
location in which you will be working.
To set the GROUND ADJUST knob for the air test, turn the knob four turns clockwise and then
turn the knob one half turn counterclockwise. No further turns will be needed for the air test.
Perform Air Test in All Metal Mode
Once you have set the correct threshold tone and adjusted the ground balance, you are ready to
perform the air test in the all metal mode. Your Tejón is currently in the VCO-style of all metal
mode. You will find that as targets get closer to the coil, the threshold tone will get louder and
higher in pitch.
Try waving your targets in front of the coil. Start from a distance of 10 to 12 inches away from
the coil and slowly work your way closer to the coil. Then try starting from 6 inches from the left
or right of the coil and work your way into the center of the coil. Notice the changes of the audio
signal. Your strongest signal will always be closest to the center of the coil. Additional target
information can also be learned by the signal strength and pitch. A smaller or deeper target will
give a less noticeable change in the threshold tone than a larger or shallower target will give.
