Tejon question about DISC and loss of depth

[sandtrout]

I use a Vaquero. Called Tesoro and they said that when adjusting the DISC, that the farther right you turn that knob, the less depth you get so....when you find a target (say in the 6+ inch range) and you turn the DISC knob to the right to see where it "falls out" that in some cases the target might not really have fallen out but instead, it dropped out of range due to loss of depth. On the tejon, let say the first disc knob is set to knock out iron and the 2nd disc knob is set to knock out pulltabs....are you losing additional depth when it's set set at the pulltab mark? Is this question making any sense?

 

[Dan-Pa.]

Makes sense to me and always give and take-aways.....high disc. will just cause a loss of depth will just about all units even with the dual disc. of a TeJon...The same goes if you are using a notch unit as with notch being used expect a loss of depth...Some experimentation is in order as sometimes the loss is little and sometimes several inches..For this reason many using a unit with a linear disc. learn to thumb the disc. when hunting and start a out with minimal disc...to get Max. depth....A metered or multi tone unit certainly is an edge when looking for extreme depth as the operator runs at minimal disc. and uses the meter or tone to get an idea what he has found in the ground before digging...

 

[tvr]

Did a quick sketch to try to visualize things. Click on it to make it bigger. Sketch is not to any scale, nor is it intended to show the true filter or discriminator characteristics of any actual design (in other words it is a visualization attempt and not a model of a design).

I estimate that in good ground with high sensitivity setting you might detect US coins at around 8 inches, that is about where the top of the curves end up.

For the curve on the left, the discriminator is set to knock out small nails. Any target that has a conductivity and depth that falls under and to the right of the line is being detected and anything that falls above and to the left of the line is not detected. Look closely at the curve and you see that the nail may click a little if it is on the surface, but it is set to discriminate them out in the ground. With that setting you will detect a nickle clearly at nearly full depth.

The second curve, the one more to the right, a nickle is discriminated out on the surface and at any depth. A shallow tab may be detected very well on the surface, but starts to get discriminated out as it gets deeper.

As you turn the discriminator more clockwise, the curve moves to the right. In most detectors I've used, the maximum discriminator setting still lets you detect copper pennies, dimes and quarters at good depth.

Hope this helps and does not confuse things more.
tvr