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FOR A CONVENTIONAL DETECTOR
If you are using a conventional detector, with Sensitivity, Threshold Tone and Discrim adjustment controls, try increasing the Threshold Tone setting, then lowering the
Discrim setting, and finally increase the Sensitivity setting.
Do these adjustments one after the other, checking if you can pick up the coin signal after each adjustment.When you have regained the signal, add another book. If you can only add a 1 cm book before losing the signal again, you are at an optimum setting, and this should add up to some nice finds.
This test will help you to understand your detectors capabilities and will also help you to know what adjustments to make to give you a little more depth when you hit a good area. Always set Sensitivity as high as
possible, as long as your detector remains stable.
COMPUTERISED DETECTOR
If using a computerised detector, like the Whites Eagle Spectrum or XLT, or DFX carry out the above test in the same way, whatever program you use. Do not try and create a special program for this test. This test is all
about making adjustments to your favourite and best inland program, the one that you normally use. Then try this upgrade. Go into Pro Options and select Audio, and turn Tone ID on, and Modulation
off, "don't turn Modulation off on the DFX"! Then go into Basic Adjustments and turn Mixed Mode Audio on, and set DC Sensitivity to 55. This should enable you to add another 4 to 5 cm of books
before loosing the signal from the coin.
You can only carry out this upgrade in the field if your program has a low Preamp Gain setting
- no higher than 2 or 3. Don't bother to use this upgrade if your Program has a high Preamp Gain setting, as your Eagle or XLT will be too erratic to use.Some operators favour a high Preamp
Gain setting of 5 or 6, with a low AC Sensitivity of 64 to 68. Thank goodness whites has capped preamp gain at 4 in the DFX. I personally prefer a low Preamp Gain of 2 or 3, anyway with a high AC Sensitivity setting at72 or 74
. To prove the benefit of using these settings, whatever program you are using, in either the Eagle Spectrum, XLT or DFX. set the
AC Sensitivity at 74 and the Preamp Gain at 2, and carry out the above test. When you get to the point where you get a faint
signal from the coin under the books, increase the Preamp Gain by one number, and at the same time drop the AC Sensitivity by two numbers - you will need to ground balance after this adjustment.
Now try and pick up the signal again from the coin. Repeat the adjustments and checks until you arrive at a Preamp Gain of 5 or
6, and AC Sensitivity of 64 to 68. on the Eagle Spectrum or XLT You will not find any change in these detectors ability to pick up
the signal from the coin, but the detector will be more erratic, giving off false signals as the loop comes off each side of the books.
with the DFX you can only increase Preamp Gain to 4, so the equivalent setting for this test would be 70 for AC sensitivity |
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If you attempt to carry out the above upgrade
, with the Eagle Spectrum or XLT, even in this controlled test, at these high Preamp Gain settings you will find the detector getting
erratic.
It will be impossible to use in the field and will pick up and send out all sorts of false signals. It won't be as critical with the DFX with AC Sensitivity set at 70 and Preamp at 4, but I favour a Setting of AC Sensitivity at 72 and Preamp Gain at 3. Don't take my word for it, try the test out for yourself. Whichever part of the world you live in, it will make you more aware of your detectors capabilities.
Good luck and good hunting!
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