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auminesweeper
04-09-2011, 01:27 PM
G Day Steve, My friend and me were talking about the gain settings on our machines, his machine being the Whites eagle II SL 90 and how you can turn down the gain but up the sensitivity and that he was finding targets in an area were we both had been over with multi frequency machines and also he had been over it with his MXT, and yet this place has been done to death for the past 40 yrs and he started finding targets again, Now he says that the MXT would have missed these targets which I donít believe because when ever he has found deep Targets I can hear them with ease and this bring me to the most Important part, IF you turn the MXT up until the threshold starts to waver then I just back it of a touch to smooth it out, Now by doing this am I over powering the ground because I donít seem to be finding any deep coins within the 9 to 12Ē mark like he has with this SL90 or maybe it is just the fact that the coil has not gone over any because when he finds deep targets and I check them I hear them loud and clear, With the reading saying GND 57 -64 so it canít be the ground. With the machine running smooth and the GAIN between 9 or 10 am I blinding the machine because i set it up the same as the book says or there about, IE DISC 2.9, Relic mode, with the Ground locked. So with these settings and everything running smooth how do I know if it is over powering the ground if it is not chattering, I dig some Iron if it is buckles or plough shears or axe heads and washers from days gone by, You can hear the threshold rise slightly as you put the coil to the ground but that is just where the ground balance is setting slightly positive
And both my MXTs are working perfectly, One is the MXT300 and the other is the MXTPRO. On the Pro I have fitted the older 950 coil so the coil is the same size as his, So is he finds it I can too, and the only thing i can think of is either my sweep speed is too slow or too fast,
I have spoken to Whites UK and they say my settings are fine

Please Help Thanks in Advance , John

Steve Herschbach
04-09-2011, 05:57 PM
Hi John,

You say you hear every target he finds. Is it just that he is telling you he is finding 9" to 12" coin targets? I'm doubtful of coins at 12". If he can get a clar signal on a target and you can't, that is grounds for worry perhaps.

From the MXT owner's manual:

This is where the new MXT can help you out.
When ground mineralization is too high for the
current GAIN control setting, the display indicates
"OVERLOAD-REDUCE GAIN/LIFT LOOP"
along with an audible "squawk". Reduce the GAIN
till the overload warning ceases.

and

Although the setting of (9-10) gives more than
ample GAIN, if the ground mineralization is low
enough, you might attempt to raise the GAIN above
this level toward +3. If, of course, "OVERLOAD-REDUCE GAIN/
LIFT LOOP" message is displayed common for
very nasty ground mineralization, you must heed it
and reduce the GAIN rather than raise it.

The object of increasing the GAIN is to get the
maximum available depth from the detector WITHOUT
causing the "OVERLOAD-REDUCE
GAIN/LIFT LOOP" message to appear which
indicates an overload of the circuit.

In addition, any increase in GAIN adjustment
should NOT BE at the expense of maintaining a
smooth and constant THRESHOLD "hum". False
signals, beeps and static from bits of mineralization,
erratic behavior, and lapses in THRESHOLD all
can be the result of running with too much GAIN.

In a nutshell, run the gain as high as you can without the machine getting unstable or showing an overload signal.

auminesweeper
04-09-2011, 08:53 PM
STEVE, thanks very much for your efforts on this one, He said that he went all over this area for a few years with his MXT (1st model), But he always ran
the gain at 6 to 7.5 so maybe this is why he never found coins this deep before, With the 300/12" I have pulled out half penny's at measured 11.5" and
never have pushed the gain above 10 although I checked it out in this area and it it quite happy at +1 and a half. So maybe it is the fact he has never turned
the machine that far up, and add on the fact that I have never used my MXTs there before, no matter what signal he finds i can always fined the target
even with matching coils. so judgeing by his past settings this is why he has never found anything that deep there, What you said above is how i have
always used my machine, and as long as my IDs are stable and accurite then thats how I run my machine. As you know how these 3000yr+ sites are hard to
work and I am the only one who is finding the old stuff, And this site is the big shops testing site,

Steve one other thing seeing as the GND reading is from 57 to 64 Will the 10" V3i coil help much, the coils i have are the 5.3, 6x10 the old 950 and the 12"/300
AS i have been told that the 10" DD has more depth that the 6x10,?.

Thanks in advance, John

Steve Herschbach
04-09-2011, 10:23 PM
Hi John,

Well, the 10" round DD will get a bit more depth than the 6x10 DD but since you are able to run a high gain with the 12" coil I am skeptical that you would see an advantage with the 10" round DD compared to the 12". But that is just an educated guess.