Tesoro Inca Operator's Instruction Manual page 3

B. COIN DEPTH. In the NORMAL position, the meter will indicate approximate depth of the detected target, assuming the target to be coin
size. In the DISCRIM mode, the depth reading feature will be inoperable.
The coin depth reading feature of the Inca is an extremely useful aid in pinpointing. The reading will reach it's maximum forward deflection
on the meter needle when the searchcoil is directly over the target, and the meter reading will then indicate the approximate target depth.
TUNING
No detector, regardless of how powerful it is, can provide optimum depth if it is improperly tuned. In fact, the more
powerful a detector is, the more critical the tuning becomes. Less powerful units are more tolerant of operator misadjustment,
but are not capable of the depth of a properly tuned high power detector such as the Inca.
To achieve maximum performance from your Inca be sure to properly adjust the GROUND ADJUST and TUNING controls
in the Normal Mode only. The settings of these controls will also affect the detector's performance in the Discrim mode, so be
sure to adjust them properly, even if you only plan to operate the detector in the Discrim mode.
Following the tuning procedures outlined below will help you properly tune your Inca, and will allow you to fully utilize its
performance capabilities.
A. NORMAL MODE TUNING.Normal Mode Tuning.
1. Set the Mode Switch to the Normal Only position.
2. Depress the handle mounted push­button switch, and turn the On/Off Tuning control completely clockwise. Check to
see that the battery reading is above .6.
3. After the battery test period ahs elapsed, turn the Tuning control down so the detector is making just a moderate
buzz. Be sure to keep the push­button depressed while setting the Tuning control.
4. Hold the searchcoil about two feet above the ground, and release the push­button.
5. Lower the searchcoil to about one or two inches above the ground, and notice any changes in the audio sound as
this is done.
6. If the audio sound level increased, turn the Ground Adjust control slightly lower. Note that turning the Ground Adjust
control will cause a change in the audio level. Ignore this change, as it is of no consequence. The only change of concern
is that change which occurs as the searchcoil is lowered to the ground.
7. Raise the searchcoil to about two feet above the ground, and momentarily depress the push­button to retune the
detector to the moderate buzz.
8. Repeat steps 5, 6, and 7, until there is almost no change in the audio level as the searchcoil is lowered to the
ground. NOTE: the ground must be free of all metallic items where the coil is lowered. If you cannot adjust the detector to
do this, you may be over a piece of metal. Move to another spot and try again.
9. Momentarily depress the tuning switch, and turn the TUNING control down to get just a faint audio buzz. The
detector is now ready to use in the NORMAL mode of operation. Once the detector is Ground Compensated, remember
the number setting on the GROUND ADJUST control, and use it as a starting point next time.
B. DISCRIMINATE MODE TUNING.
Tuning the Inca for use in the Discriminate mode requires that the Normal Mode tuning procedure be properly
accomplished, as the Ground Adjust control provides for mineral free operating in both the All Metal and Discrim modes. Also,
the threshold setting of the Tuning control determines the minimum sound level for deep targets in the Discriminate mode. Too
little threshold, and depth will be lost. Too much threshold, and the detector may become erratic.
After the Normal mode procedure is accomplished, the only settings necessary for operation in Discriminate mode is to
set the Disc Level control to the desired amount of trash rejection, and to set the Sensitivity control the maximum setting that
will allow smooth operation.
SELECTING THE PROPER MODE OF OPERATION
The Inca offers two basic modes of operation, the Normal mode (All Metal) and the Discriminate mode. Both modes are
mineral free if the unit is properly adjusted. The Normal mode is the industry standard "VLF" type which does not require
motion of the searchcoil for proper operation. This mode, while requiring an initial ground adjust setting of sound threshold,
offers two very important advantages, these being the ability to pin­point without motion, and to provide exact ground
canceling. The Discriminate mode is based on motion of the searchcoil, but requires very little motion, and offers the
advantage of completely silent operation. Push­button mode change between these two modes is also included, offering the
most versatile "one handed" operating system.
Since the threshold sound will "come and go" as the push ­button is used to change modes, a third operation mode was
added, this being the Normal Only mode. In this mode, the mode change feature is defeated, and the detector will retune to
threshold when the push­button is depressed.
The Normal Only mode is the bet mode for the initial ground adjust and threshold adjustments, since the threshold does
not go away when the button is pushed. This mode would probably e the best choice for someone who is nugget hunting or
relic hunting, and is not interested in switching to Disc.
The push­button mode change feature of the Inca allows the user the options of either searching in normal mode to find all
targets and switching to discriminate to check them, or to search in discriminate and switch to normal to pinpoint and
measure depth. The former method has historically been the most thorough way to search a given area, but the extra slow
sweep of the Inca tends to overcome most of the disadvantages of searching in discriminate, so most people will probably
operate in discriminate because of the silent operation.
Earlier motion discriminators that are operated with the "Threshold" sound would give the user a definite indication of
metallic trash by either nulling completely or by generating short, choppy sounds. Since the Discriminate mode operates
without threshold sound, there is no nulling to indicate that the area is extremely trashy. When searching in the Discriminate
mode, we recommend that you periodically switch to Normal mode and check the area you are searching to get an idea of
how much trash is really there. In extremely heavy trash areas, it may be desirable to switch to a smaller search coil, even
through doing so will cause a loss of depth. The smaller coil will allow you a better chance of finding coins between the close
pieces of trash.