Shielding for probe cables?

[TexAgReefer]

I’ve read before that some of the issues seem with probe accuracy is electrical noise from other nearby cables. Has anyone used some kind of shielding to reduce/eliminate this interference? Any other tips to reduce this issue and improve accuracy and consistency?

 

[iambenfields]

Interesting idea. I haven’t tried that but I have shielded electric guitar cavities/pick guards which can get ultra sensitive to EMF with copper tape but I’d wager you’d want to be cautious using that around any water that comes into contact with inverts or corals.

Copper Foil Tape (1inch X 66 FT) with Conductive Adhesive for Guitar and EMI Shielding, Slug Repellent, Crafts, Electrical Repairs, Grounding

 

[Pistondog]

I’ve read before that some of the issues seem with probe accuracy is electrical noise from other nearby cables. Has anyone used some kind of shielding to reduce/eliminate this interference? Any other tips to reduce this issue and improve accuracy and consistency?

Physical separation of probe wires (signal) from pump wires (power) is recommended. Before going crazy try using aluminum foil around suspect probe cables, alligator clip to ground. If that helps, then look for wrap around braided shield. If it doesn't help you are wasting money:shielding is not the problem.
What is the symptom you are trying to fix?

 

[TexAgReefer]

Physical separation of probe wires (signal) from pump wires (power) is recommended. Before going crazy try using aluminum foil around suspect probe cables, alligator clip to ground. If that helps, then look for wrap around braided shield. If it doesn't help you are wasting money:shielding is not the problem.
What is the symptom you are trying to fix?

I don’t have any problems at the moment. I’ve ordered everything for a new build, including a new full apex. I just want to do it right the first time to avoid any issues.

My current plan is to run a separate cable track just for the 4 probes. Maybe that will be enough. Just looking if there is an ideal solution as I plan and prepare.

 

[Pistondog]

I don’t have any problems at the moment. I’ve ordered everything for a new build, including a new full apex. I just want to do it right the first time to avoid any issues.

My current plan is to run a separate cable track just for the 4 probes. Maybe that will be enough. Just looking if there is an ideal solution as I plan and prepare.

That sounds like a good plan. I don't recall apex suggesting shielding. I thing the probe cables are coaxial, which means thereis central signal wire surrounded by the reference ground, mylar foil or braid. With a solid ground connection to the apex, the ground should prevent noise issues. This is similar to broadband cable, the sheild is the coaxial braid around the central core (digital) signal conductor.
I have not had good luck with the Apex salinity probe, just ordered another to try again. Because of the nature of the conductive measuement it is subject to any other electrical device (pump) leaking voltage into the water. This would not get fixed by additional shielding.

 

[TexAgReefer]

That sounds like a good plan. I don't recall apex suggesting shielding. I thing the probe cables are coaxial, which means thereis central signal wire surrounded by the reference ground, mylar foil or braid. With a solid ground connection to the apex, the ground should prevent noise issues. This is similar to broadband cable, the sheild is the coaxial braid around the central core (digital) signal conductor.
I have not had good luck with the Apex salinity probe, just ordered another to try again. Because of the nature of the conductive measuement it is subject to any other electrical device (pump) leaking voltage into the water. This would not get fixed by additional shielding.

Makes sense. Thanks!

There was an article posted on here last week I think specifically around setting up the salinity probe. I bookmarked it to follow the process. I don’t care if it’s exactly accurate, just consistent. I want to know if there are sudden other even long term shifts.

 

[iambenfields]

Physical separation of probe wires (signal) from pump wires (power) is recommended. Before going crazy try using aluminum foil around suspect probe cables, alligator clip to ground. If that helps, then look for wrap around braided shield. If it doesn't help you are wasting money:shielding is not the problem.
What is the symptom you are trying to fix?

Aluminum foil is far less effective than copper. And I’d strongly disagree that shielding isn’t the issue if the problem is caused by emf noise from crossed wires. It quite simply is the issue, plainly. Running that to ground may, or may well not solve the problem.

 

[Pistondog]

Aluminum foil is far less effective than copper. And I’d strongly disagree that shielding isn’t the issue if the problem is caused by emf noise from crossed wires. It quite simply is the issue, plainly. Running that to ground may, or may well not solve the problem.

Proper shielding runs the emf to ground so it cannot influence the signal. Using aluminum foil is a quick test to see if that helps solve the problem. All hypothetical problems that don't exist in ops new system.

 

[iambenfields]

Proper shielding runs the emf to ground so it cannot influence the signal. Using aluminum foil is a quick test to see if that helps solve the problem. All hypothetical problems that don't exist in ops new system.

Absolutely, what I’m describing is a rough-and-tumble faraday cage-ish thing... because the OP probably (like most of us) Likely doesn’t want to go to the lengths of grounding whatever he finds works to earth - either with a dummy plug or the probes earth, my suggestion was a halfway mark given what I’ve experienced with my own salinity probe.

FWIW - they’re notorious for their sensitivity to electrical noise and even though they are internally shielded (according to @Pistondog ) that shielding doesn’t seem to do much in our real-world 15,000,000 cables running everywhere world.

 

[robbyg]

Just put Ferrite beads on both ends of the cable.

 

[TexAgReefer]

Just put Ferrite beads on both ends of the cable.

Thought about this as well.

 

[robbyg]

Thought about this as well.

Just measure the Diameter of the cables and then order the size that will clamp down tightly on your cable. I suspect the 3mm size should do it.

I have been using Ferrite beads to keep 1500 Watts of pure RF power out of my Audio equipment. They are only 5 feet apart and without the beads I get massive feedback through the stereo. With the beads nothing! Everything is filtered out.

Link
https://www.amazon.com/s?k=ferrite+core&ref=nb_sb_noss_2