34 Garrett Metal Detectors
AT Max
™
35
Bench Tests
You should conduct bench tests to become more familiar with
the
AT Max
’s operation in both ALL METAL and Discrimination
Modes. In addition, the use of the Iron Audio feature should be
tested in each mode. Suggested test items should include:
• Coins
• Iron nail
• Bottle cap or steel washer
To conduct a bench test, place the searchcoil on a flat, non-
metallic surface that is several feet from other metallic objects.
Begin by testing in the ALL METAL Mode. Pass the test items
individually across the searchcoil at a distance of 3 to 4 inches
(8–10cm). Observe the Target ID for each. Next, select the ZERO
Mode and pass the same targets across the searchcoil. Use both
large and small test pieces at varying distances from the searchcoil
to observe the levels of their responses.
For bench testing, place the searchcoil on a flat, stable, non-metallic surface
that is several feet from other metallic objects.
Discrimination bench test:
A similar test procedure can be
used to better understand how to set iron discrimination levels.
Pass the iron nail across the searchcoil while in either ZERO or
COINS Mode. Note that in ZERO Mode, with the factory preset
level of zero (0) Iron Discrimination, the nail produces a Low Tone.
If the iron nail registers up to a 26 on the Digital Target ID, increase
the Iron Discrimination setting up to 26. Pass the iron nail across
the searchcoil again to verify that it has been eliminated. If not,
raise the Iron Discrimination setting a little higher until the iron
target no longer produces an audible response. The factory preset
Iron Discrimination level of 35 in COINS Mode will eliminate most
iron nails from detection without adjustment.
Iron Audio bench test:
Next, remain in ZERO Mode with your
Iron Discrimination level set to remove the iron nail tested in the
example above. Press the IRON AUDIO button and pass the nail
across the searchcoil again to hear the distinctive iron sounds.
Then, test this nail in the ALL METAL Mode. Switch on the Iron
Audio feature, set IRON DISC to 26, and pass the nail completely
across the searchcoil again. The distinctive Low-Medium-Low
response indicates that the target is unmistakably iron.
Flat iron objects like bottle caps or steel washers can appear
to be good conductive targets to detectors. To test the
AT Max
's
advanced iron recognition abilities, conduct another bench test
with an iron bottle cap. First, set the detector to the ALL METAL
Mode, switch off Iron Audio and pass the bottle cap across the
searchcoil at a distance of 3 to 4 inches (8–10cm). Note that the
bottle cap's flat surface gives a Digital Target ID reading generally
in the 40–60 range.
Remaining in the ALL METAL Mode, switch on the Iron Audio
feature and set IRON DISC at 35. Pass the bottle cap completely
across the searchcoil again and listen for the distinctive Low–
Medium–Low response indicating an iron target. This ability to
check iron targets while operating in a true ALL METAL Mode is
