Question on nulling

[joecoin]

Iron mask on, no notch. Sensitivity auto, volume full, threshold nice steady hum. This means I am only discriminating ferrous objects, right?


If my Sovereign GT nulls, but after the null the pitch has risen, does this mean there is a non-ferrous target in the area just swept?

 

[Rick(ND)]

The disc also has to be all the way counter clockwise and you will reject most of the ferrous targets. Some bigger and some others may give a signal on the edge of the ferrous item, but it will not be a repeatable signal like a good target will be. Now when it nulls and comes back with a threshold it should be a low tone and almost a growl sounding tone is normal, but one that is a higher pitch after the null should be checked out to see if it is a repeatable signal by just going over that small area where the signal is positive. If it is repeatable and don't move then come at it from a different angle and see if it is still repeatable if it is and the tone or numbers you want to dig than dig. Some iron will repeat sometimes with iron mask on, but when coming from a different angle it will null or not repeat or even move, those are the false signals..

 

[mattockman]

n/t

 

[joecoin]

Rick,

Yep, Disc is all the way CC. What seems to happen a lot is this;

I'm sweeping along, minding my own business, when suddenly I get a null. Immediately after the null lets go, the threshold comes back at a higher pitch than the usual "iron growl".

So, I go back over the spot, SLOWLY, I get the null, then the pitch will sometimes go back to iron growl, or come back at the higher level. So I'm thinking this is a good target next to a piece of iron. So I go real real real slow, but then I get just the null, when the threshold returns it's the iron growl. But then, if I return my swing speed back to its usual slow speed, I get the null with the higher tone after the threshold returns. Now, when I say usual slow speed , I mean I am going my usual SLOW speed. It is when I slow down to a crawl that the higher pitch does not occur. (My definition of "slow down to a crawl" - I do not move my feet. I place the coil on the ground. I move the coil maybe 2 inches, then stop. Then I repeat.)

Every time I have bothered to dig one of these targets, it's been a nail or other iron junk. Usually a nail.

I'm glad that it will soon be too cold to detect.

 

[joecoin]

n/t

 

[Mike (Virginia Beach)]

The best rule of thumb in this situation (unless you want to be doing a whole lot of fruitless digging) is that you DO check it out, as Rick said...but if you can't get a REPEATABLE good signal (even if it's broken up and raggedy, but REPEATABLE) then move on. I wouldn't dig too may signals based on null alone. You should be able to make it a good signal from SOME angle with the right sweep. That's my criteria anyway.

 

[mattockman]

I was gonna say it will most likely be Iron......more times than not it will be iron in that situation......it is a tough call.....the metal lobster pots will be a hinder and so will nails......so just dig and learn.....thats all I can contribute.....learn from digging.....it won't take long.

 

[joecoin]

So as long as the pitch stays the same, even if it's a broken signal, investigate?

 

[mick]

I hit some galvanized nails the other day that sounded pretty good. I had the iron mask on and there was a nice thick coating of zinc on each nail. I guess it fooled the sovereign and me too. All part of the learning curve.

mick