Fisher Gemini-3

9
Tuning
1. Set the transmitter:
Power: ON
2. Set the Receiver:
Power: ON
Sensitivity: 7
You should get a strong audio tone and meter
indication at this point.
CAUTION: Never attempt to tune the GEMINI-3 in the
presence of metal objects likes cars, metal walls, roofs
or heavy metal reinforcements in any structure. Their
presence will make proper balancing impossible.
3. Pick the unit up by the handle and balance it so that
it is level with the ground and at normal carrying
height (arm’s length). Five cm higher in the front is
OK. For a deeper search, attach the fully lengthened
carrying strap to the eyelets at the ends of the handle
(see illustration on page 9). You will need to hold
the instrument at this lower level while tuning if you
plan to use it lowered. On some highly mineralized
ground and some asphalt, you may not be able to
use it with the strap fully lengthened. You will know
this during tuning if you cannot reach a silence (null).
Not reaching a null can also indicate the presence of
nearby metal. If this is the case, move away from the
metal to balance your GEMINI-3 to the ground only.
4. Still holding the GEMINI-3 parallel to the ground, slowly
turn the BALANCE knob (with arrow) on the three-
piece handle counterclockwise until you get silence
(null) and zero meter reading. At this point there
should be no sound as you rotate the knob 1/8- to
1/4-turn further counterclockwise before reaching
sound and meter reading again.
5. If you cannot null the audio or your null point is less than
1/8 turn, reduce SENSITIVITY slightly and try again.
6. If you can turn the BALANCE knob more than 1/4 turn
without an increase in the sound or meter, increase
SENSITIVITY slightly and try again. Keep adjusting as
described until 1/4 turn of silence (null) is achieved.
SEARCHING
16
Tuning
1. Set the transmitter:
Power: ON
2. Set the receiver:
Power: ON
Sensitivity: ZERO
3. Slowly increase the SENSITIVITY control until the
audio signal is heard, then reduce SENSITIVITY until
the audio just disappears. This is the point at which
air coupling has been eliminated.
Operating
1. Locate the buried pipe by circling the contact
point, keeping the receiver in line with the
contact at all times. Stay at least 30 feet from the
transmitter.
2. Once the pipe has been located by a sharp
increase in audio and meter signals, the pipe may
be traced exactly as described in the operating
section of the Inductive trace instructions.
3. Be aware that a nonconductive gasket in the pipe
will terminate the RF signal from the transmitter.
TRACING
Figure 9. Conductive Trace