It aint necessarily so

Over the years we read lots of posts by folks complaining about EMI (no, not the record company).
I am of the opinion that most of their problems are with their detector settings and not the atmosphere or power lines or old Burt's electric fence etc, etc, etc.

Like nearly all problems with detectors on the ground, I truly believe it all comes down to incorrect settings and just plain not knowing how to use the detector.

Just my opinion. Yours may be different.

Robert

I'll 2nd that

Now as we all know the GPX Manuals tell us to hold the detector at roughly knee height with the coil
90 degrees to the shaft like a T section when doing an Auto or manual tune, and in a few cases this works
fine, but when you lower the coil down to detect and do a GB you will find there is still some EMI there.

I believe this is caused by a type of "EMI Skin effect" over the heavy mineralization at detecting height
that exists at that level, so in most cases you are actually better off goin against the Book Method and do it this way.

Hold your coil at 45 degrees from the ground surface and have the lower back edge of the coil only about
100 mm from the ground, now do a slow full rotation listening for the worst EMI direction, and pointing
in that worst direction either do an Auto-Tune or Manual Tune.

Doing it this way you will find you get far less EMI when detecting and also when you have your coil
on an angle detecting sides of gully's and mullock piles.

Pete

I'm going to disagree with this thread :). But let me explain.

I've worked on patches where i've had the 5000 purring, then a gust of wind comes along and the machine sounds off like i have a target under the coil. With this EMI there is nothing i can do to eliminate it.

Othertimes i have worked closer to powerlines without any EMI and this was eliminated by doing the GB as per the users manual.

Agreed that setting do cause a lot of problems.
The difference between 8 and 10 on the gain is the difference between hearing and not hearing a signal sometimes. If the EMI is bad with a gain of 10, its equally bad with a gain of 8...the difference is hearing the target on 10 with persistence vs not hearing it at all on 8.
You may lower your settings to smooth out some EMI .... but the EMI is still there no matter what settings you use.

You welcome to borrow my extreme for a weekend, on a windy day, with a lightning storm, near the RAAF base and CDI ignition 2 stroke motor bikes.......
P.S loving the 5000 i barely hear a whisper now.....

Pete
I reckon trying all sorts of positions for autotune. As per your method, also with the coil on the ground or any other position you can think of. As we know, there are a few things in the manual that leave a lot to be desired.

Goldbait

Yeah, I understand that some days no matter what you do you can't eliminate it.
I directed my statements more at folks that can't work out how to tune it out or
just like to blame EMI for their lack of experience.

Robert

I pretty much run my GPX 4000 with the same settings at every location I detect(except the Gain).
But the last trip out did my head in. My mates Extreme and 3000 were also going off their heads from the word go.No matter what we did it was an early beer day.
The next day started off good,but by BeerOclock the same thing happened.
It was an epic fail weekend.