Is there any way to get rid of EMI effecting our metal detectors, besides detuning?

[stevemc]

I mainly use PI detectors that are very sensitive. They pick up EMI from power lines and transmits(Bluetooth and earphones) from cell phones on the beach. Is there anything besides detuning so much we cannot hear it? Last week a friend that has a dive shop / detector shop took me with him, or I took him with me, to the beach to test out the new Minelab Equinox. First someone turned on their earphones, about 30 feet away, started getting static on the Equinox, we moved. Later we moved down near the waters edge beach and static again. We couldn’t find the rings we buried in wet sand with the Equinox and I got out my Whites Dual field and did have wa wa wa wa from cell phones but could hear through it, and found the ring. Disturbing to have that and have it diminish the the pick up on the detector. Is there anything that can stop that? I know the Whites coils and cables are shielded, but the coils are-like antennae’s and pick up any stray signals.

 

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[WaterWalker]

I have seen where some have used a snap-on RF / EMI filter (choke / ferrite core) around the coil cable.
I do not know how effective they are but for a couple of bucks one might help.
I have two cameras that came with a USB cable that have one of the ferrite cores on the cable.

If you try one, let us know how it works for you.

 

[OBN]

No effect with the ferrite core choke, hard wired a coil, if I remember correct had a couple on it.

Before Minelab even had shielding on the Excalibur 2 I was working with it on the old blues, never any luck.



The only shielding I have come up that worked was being able to hunt in ruff waters and have a (almost) silent threshold. No falsing.

 

[Jim in MA]

This is what I did to my Blue I had a spot next to my knobs that if you touched it would false.
I raped it in static bag I cut up and the falseing stopped to the touch.
It runs smooth but who knows when it is working or there is no interference out there.

 

[OBN]

Great Idea Jim!!

I know Mike and I had talked about redoing a complete new Pod that would be shielded on the inside with no knobs other then a charge port and toggle, on/off. Never got around to it but I really like your idea!!

 

[stevemc]

OBN, I know Whites uses a spray in nickel shielding in their coils. It can be bought in an electronics store or I am sure found on line. I have used it in the past to prevent cross talk and alien cross talk, in building up detectors and fish finders, etc. works fine. Maybe painting the inside of the battery box and controls box might help.

 

[WaterWalker]

Not EMI, but interesting (at least to me).

My Infinium would false every time the control box would enter or exit the water, fresh or salt.
Then I noticed that touching the coil connector I could make the "falsing: happen. I wrapped the connector with electrical tape, problem was gone...
Later in my life, I read that Garrett had a ground wire to the connector and it should be removed to correct the falsing.

I hesitated for a few years as I was unsure of how to open the Infinium. Finally found the instruction and after a five minute task I have never has it false again. Since then I have removed the ground from three other Infiniums all with great success.