Mixed signals...Xterra and Etrac

[Terra1959]

Gday,

My Xt70 (standard coil) and I recently went modern coin hunting with a regular detecting friend...he runs an Etrac with standard coil.
I swept through an area which was good to me, I commented to him how good it was and we decided to return to the spot to see what i missed.
He straight away picked up a signal which he said was a $1 coin.
I swept over the same spot and my signal was 18 - way off ! ... a $1 coin is 32 on the xterra
I would not normally dig an 18 when modern coin hunting...a 20c coin is 20 - 22 .
18 is usually junk in my limited experience
..so I swept in different directions , then also put the machine in All Metal and the result was the same.
He then dug up the coin and it was a $1 coin, along with 2 more very close by.

I am a bit confused as to why / how this happened.
I have had multiple targets alter my TID readings before but with 3 coins the same ...never.
Also I have had reading 24 (50c coin) then dug it up, swept over the spot again and got a 32 ($2 coin) then dug it up...the larger 50c coin had obviously hidden the smaller $2 coin reading.
I know my 9" coil is concentric and his 11" is DD ( I think ), but still ...what the #%^&* ??
The only thing that i can think of is if there were other lesser coins eg, 5c, 10c, 20c in the same hole that confused the Xterra ?

Anyone else had similar experiences ??

Oh, yeah the Xterra works fine and I actually found more coins and $ than my mate with the Trac for the mornings session.
happy detecting everyone.

Terra1959

 

[lozz38]

Hi Terra,
Interesting results there. I could never imagine a $1 coin coming in at 18 as that's way down in the junk pull tab range as you point out, but I did once have a $1 coin register at 28 instead of the normal 32 and it looked just like any other $1.
I remember thinking at the time that maybe the metal alloy of Aluminium, Copper and Nickel was not mixed up properly and that was to blame for the different reading. A lot of our $1 and $2 dollar coins were made in SE Asia where maybe the quality control is a bit dodgy.

It's also certainly possible that other metal in the ground is masking the reading that the coil is getting.

Have you taken off the coil cover and cleaned out the dirt lately? Sometimes that can give false signals and alter readings.

Might have to dig some 18's for a while and see what turns up.

Good luck, loz

 

[Mick in Dubbo]

I'm with Lozz on this one.
I have had A $1 coin read 24 on the X-Terra. It had a small amount of corrosion on it. I actually found the coin with my Explorer and it read 23 on it. I picked as a coil because of the way the audio sounded. Although the tone was off for a goldie, it still sounded like a coin.
I've never had one go so low as what you have. It could have done it if there was a lot of corrosion on it. There must have been something else at play here to skew the numbers like that. I wouldn't be too worried about it, even though it can be a bit irritating when you see you've missed something that you think you should have gotten.
Mick Evans.

 

[tony (Orlando FL)]

The stock coil on the x70 is a concentric type, the trac comes with a DD coil which is why he wasnt affected by the averaged out or lower ID #s. Its just a hunch on my part.

 

[SteveP(NH)]

If your ground is at all mineralized it could also explain the incorrect target ID readings. The Etrac is using a DD coil (which is less affected by mineralized soil) but also is a multi-frequency machine and so that also makes it more capable at handling mineralized conditions.

One thing you can do to improve the target ID readings is to set your ground balance slightly (1 or 2 points) positive as this should help the machine get a better read of the differences between the soil and the target. Since the 70 doesn't have track offset like the 705 does you will also have to run without the ground tracking turned on to preserve your positive balance as the auto track would cancel your offset.

BTW I mean running the machine so that the ground has a slightly positive reading to the machine not setting a higher number in the manual gb setting - you have to subtract a number or two from the gb setting in order to make the ground read positive.

 

[Terra1959]

G'day,
Thanks for your replies good people.

the coins were not old and corroded , I too have come across altered readings when the coin jackets start to break down - but 18 ?

.... Lozz, I have had $1 coin as low as 28 but not your 24 and no where near 18 before.
the coil and inside / outside the cover had only just been cleaned the night beforehand as i had a dirty hunt 2 days before.
You could be right about about other coins of lower value in the ground also masking out the $1 signal.
None were dug up by my friend when he got his 3 x $1 out, but he may have left them there , we were cherry picking only the 20c, 50c, $1, $2 coins that day.

The ground was fine..it was not mineralised.

Tony...I have a feeling that you may have it right, ie. the differences between the DD and the Concentric in seperating the very close by coins.
Maybe somehow the concentric did sort of average out all those very close together signals ...and arrived at 18 .

As i said I out hunted him ( for the 1st time ...I'm not usually competitive, but he usually wants a count at days end and delights in beating me) on the day so I'm not too worried...just wondering why ?
Thanks again...happy tecting

Terra1959