Page 11
TDI SL
Owner’s Manual
Pulse Delay
affects the ground balance point, so whenever
the delay is changed the ground balance should also be checked
and re-adjusted. Higher pulse delays require a lower ground
balance setting.
Target Conductivity
The
Target Conductivity
switch
allows you to select between high-only,
low-only, or all target responses (see
the
Principles of Pulse Induction
sec-
tion for details). There are two caveats
with this switch. First, the two-tone
response, and therefore the functional-
ity of this switch, are disabled when ground balance knob is
turned to the
OFF
position. Second, in order to ground balance
the TDI this switch must be set to the
ALL
position.
Be aware that target conductivities can vary considerably,
even targets of the same metal. Small gold nuggets are usually
low and large gold nuggets are usually high, but where the tran-
sition occurs depends on the composition of the gold alloy. Be
mindful that searching in low-conductivity mode could elimi-
nate very large nuggets, if any happen to be in the area
1
.
The same is true for relics and jewelry. Many bullets, but-
tons, and most buckles register as high conductors, but cuff but-
tons often respond as low conductors. Most small jewelry
responds as low conductors, but larger men’s rings can easily
fall in the high-conductive range. Most coins fall in the high
range, except for e.g. US nickels and small or thin coins like
hammered silvers or very small bronze coins.
1. The potential for Very Large Nuggets depends on where you are
detecting. In most gold-bearing regions of the US, detectable
gold is found as small placer nuggets up to multiple grams in
size which register as low conductive targets. Alaskan and Aus-
tralian gold is still being found in multiple ounce-sized nuggets,
which may respond as a high conductive target.
