Equinox and EMI

[Kapok]

Hunting yesterday with my 600 and hit some really bad EMI. I switched from Multi to 15kHz and lowered my sens down to about 17, which helped but not entirely. However, my partner who was using an AT Max was having no issues at all. He was giving me some good natured ribbing about it. But I'll admit even after all these years I still don't understand how EMI can affect one detector and not another.

 

[Historical Prospector]

I too, have been having higher than normal issues with EMI in my hunting areas. I have tried everything I could and finally came up with a solution that works for me. I found that if I notch everything under 18, the EMI interference goes away and I have a very smooth detector. I would prefer notching out the lower numbers than dropping the sensitivity of the detector. I know I'll miss some smaller gold items and nickels, I am OK with that.

 

[Jason in Enid]

Hunting yesterday with my 600 and hit some really bad EMI. I switched from Multi to 15kHz and lowered my sens down to about 17, which helped but not entirely. However, my partner who was using an AT Max was having no issues at all. He was giving me some good natured ribbing about it. But I'll admit even after all these years I still don't understand how EMI can affect one detector and not another.

Because it depends entirely on the frequency being used, and the nature of the EMI. Same say Multi-freq is more resistant to EMI, others say it more prone. I don't know, because every model of detector uses different frequency and even within different detectors of the same model can be slightly shifted. I know my CTX was a lot better at handling EMI than my older detectors, but the EQX seems to suffer a little more.

 

[Southwind]

Some of the schools I hunt have alarms that cause EMI noise on my 800 but generally I just do a Noise Cancel and it drops it to a useable point.

 

[lytle78]

The Nox is extremely sensitive. At high power settings it is running at the ragged edge - add to that using a DD coil and it’s going to be a lot like an F75 - turn the power down - you will probably not lose much depth.

 

[coin-star]

I think it is a variety of factors including coil type, shielding, frequency of EMI, etc. I posted in the Makro forum my experience where a concentric could hunt on top of a buried power line with no issues where my 11DD went absolutely bonkers.

Logic tells me that shielding against EMI over 5 frequencies would be more difficult than shielding 1 frequency. However, if you had a circuit smart enough to recognize the frequency being affected and either shift it to to a "clean" frequency or lower it's gain, a multi-frequency detector COULD be far superior. That means you have to have something measuring signal-to-noise on demand or constantly. Many Wifi routers and access points have a radio specifically for analysis of congestion and shift to a less congested band.

Kapok, I am guessing noise cancel had no effect lessening the EMI interference?

CS

 

[treasure_hunter]

If you have a cell phone on you turn it off and see if the EMI goes away.

 

[Jason in Enid]

I too, have been having higher than normal issues with EMI in my hunting areas. I have tried everything I could and finally came up with a solution that works for me. I found that if I notch everything under 18, the EMI interference goes away and I have a very smooth detector. I would prefer notching out the lower numbers than dropping the sensitivity of the detector. I know I'll miss some smaller gold items and nickels, I am OK with that.

Good post! I'll have to give that a shot in some of my bad EMI spots. Losing the chance at nickels and most gold would suck, but it better than not being able to search a location. At least I could still silver scalp!

 

[Kapok]

I think it is a variety of factors including coil type, shielding, frequency of EMI, etc. I posted in the Makro forum my experience where a concentric could hunt on top of a buried power line with no issues where my 11DD went absolutely bonkers.

Logic tells me that shielding against EMI over 5 frequencies would be more difficult than shielding 1 frequency. However, if you had a circuit smart enough to recognize the frequency being affected and either shift it to to a "clean" frequency or lower it's gain, a multi-frequency detector COULD be far superior. That means you have to have something measuring signal-to-noise on demand or constantly. Many Wifi routers and access points have a radio specifically for analysis of congestion and shift to a less congested band.

Kapok, I am guessing noise cancel had no effect lessening the EMI interference?

CS

No effect, unfortunately.

 

[Kapok]

I too, have been having higher than normal issues with EMI in my hunting areas. I have tried everything I could and finally came up with a solution that works for me. I found that if I notch everything under 18, the EMI interference goes away and I have a very smooth detector. I would prefer notching out the lower numbers than dropping the sensitivity of the detector. I know I'll miss some smaller gold items and nickels, I am OK with that.

I will try that next time. I can't imagine why that would work, but I'm no electronics engineer.

 

[Kapok]

The Nox is extremely sensitive. At high power settings it is running at the ragged edge - add to that using a DD coil and it’s going to be a lot like an F75 - turn the power down - you will probably not lose much depth.

I'll give that a shot. I made the same mistake with my Multi-Kruzer. Maxing out the gain is like driving in a snowstorm with your brights on.

 

[Historical Prospector]

I've tried that, it didn't help me.

 

[TomNH]

EMI, RFI, QRM ........ whatever
First try what Debbie from ML suggested at a seminar. If you thing you know the source point your coil at
it & do a noise cancel. You can also be selective as to when to MD. In other words DONT detect a welding shop
when they are working ! Wait til they are closed...... Same with schools etc.
Probably the main reason for it effecting some detectors is the different freqs they run at. Even if the same they
will be off a little. In other words 5Kh isnt held at 5,000.0000, it will vary.
FBS probably eliminates any noisy freqs from a large list. MIQ probably shifts freqs a little when noise canceling.
What ever the case we have to learn to live with it. The way electronics are now & the lack of regulation of "noise"
emitted is only going to get worse. If you want dirt cheap TV's etc you must pay a price.
BTW you need to pull the battery to kill a phone. It still runs when off to some extent.

HH Tom
LFOD !

Hunting yesterday with my 600 and hit some really bad EMI. I switched from Multi to 15kHz and lowered my sens down to about 17, which helped but not entirely. However, my partner who was using an AT Max was having no issues at all. He was giving me some good natured ribbing about it. But I'll admit even after all these years I still don't understand how EMI can affect one detector and not another.

 

[martygene]

Funny thing about EMI... Was detecting a house yesterday with my buddy. He was using the CTX and the EMI was killing him and I was in multi on the NOX and once I noise cancelled it was smooth as silk. He could noise cancel all he wanted and no dice. Go figure, right?

 

[Always Curious]

For what it's worth, I have found EMI on the Nox to be more manageable than with the Etrac. Usually, after noise canceling, I can run pretty much at full power, although sometimes I do have to dial it down a bit to control the chatter. I did run into one or two park sites with underground cables that it could not handle (although moving to a quieter end of the park eliminated most of it). In short, I think Minelab shielded the Nox reasonably well.