Are suppression ferrites really needed on Raymarine instruments?

Ward H

Ward H

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Nov 7, 2011
3,649
Catalina 30 Mk II Barnegat, NJ
This weekend I installed two RM i70S displays and a P70S control head into my existing nav pod. The pod also contains a SeaTalkng 5 way connector, T connector, spur cables and the Axiom 7 CP power cable and spur cable.
The nav pod is a bit cramped and the suppression ferrites on the spur cables of the i70S and P70S displays complicate laying out the cables so I don't have to sit on the pod to close it.

The suppression ferrites are user installed. I was wondering if I could remove them without affecting the operation of the instruments.
Are they really needed?

Pedestal Guard.jpeg
 
Mark Maulden

Mark Maulden

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Jan 25, 2011
2,399
S2 11.0A Anacortes, WA
What this means is that noise suppression (in or out) is not on the circuit board where it belongs so they put a ferrite around the cable which is much less effective and cheaper. So, do you need it? Maybe..Maybe not. You could run a test and turn everything on without the ferrites installed and note any interference on the RM system. You need to note any on the other boat systems also. It’s a two way street. This includes radio transmissions and reception. Sometime later, when changes are made, you do this all over again. And then, if everything passes, what is the margin? Will you have a problem with some other outside RF source if the margin is low? So, nobody can really answer if they are needed or not. The design of the product includes the ferrites so I would install them. Can you make the connections below the cockpit sole?
 
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D

dlochner

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Jan 11, 2014
11,401
Sabre 362 113 Fair Haven, NY
Mark Maulden said:
The design of the product includes the ferrites so I would install them. Can you make the connections below the cockpit sole?
Click to expand
On the devices that I have had to install ferrites the manual stated to install them as close as possible to the device. Under the cockpit sole would place them about 3 feet away. How effective would them be at that distance?
 
RoyS

RoyS

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Jun 3, 2012
1,742
Hunter 33 Steamboat Wharf, Hull, MA
I have older Raymarine instruments installed at the helm in Navpod enclosures. These instruments came with ferrites to be installed on the cables within the Navpods. I installed all that were provided without giving any real thought to what benefit they might provide. Sometime later I started using a portable UHF handheld radio at the helm and battled with non-stop static that could not be squelched out. Trial and error revealed that the source of the static was the instruments within the Navpods. Several sailors here on this forum suggested to add more ferrites. I ordered some (inexpensive) on line and placed them on every cable inside the Navpods and the radio static was gone. So yes, you probably need those ferrites and possibly more.
 
Ken Cross

Ken Cross

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Oct 24, 2010
2,405
Hunter 30 Everett, WA
The only way to know is to test. Just try it without them. The pod need not be closed up as long as the lay of the wires is similar to the closed up position. hold it close with tape if needed. Putting the beads on the cable down below the helm may or may not work. I'd suggest experimenting. Using a handheld VHF nearby is a good idea for testing and as mentioned earlier, be sure to have everything running including the engine. If everything works, you're golden.

Ken
 
Mark Maulden

Mark Maulden

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Jan 25, 2011
2,399
S2 11.0A Anacortes, WA
dlochner said:
On the devices that I have had to install ferrites the manual stated to install them as close as possible to the device. Under the cockpit sole would place them about 3 feet away. How effective would them be at that distance?
Click to expand
The ferrites would still be in the pod. Can the T connectors etc be done below the sole?
 
DArcy

DArcy

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Feb 11, 2017
1,702
Islander Freeport 36 Ottawa
Ward H said:
Are they really needed?
Click to expand
The short answer is probably. Suppression ferrites on cables are a bandage added on to cover up questionable electronics design. Most likely, there are cheap, noisy power supplies inside the devices spewing out RF emissions. RoyS' observations sound fairly typical. Note that what he observed is radiated emissions but you may also have conducted emissions which could effect anything on the same power or communications buses through the cables. If you don't install the ferrites you will most likely be in violation of the FCC compliance certification of the device - so watch out for the FCC police ;)
 
Ward H

Ward H

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Nov 7, 2011
3,649
Catalina 30 Mk II Barnegat, NJ
Mark Maulden said:
Can the T connectors etc be done below the sole?
Click to expand
I suppose it can be done that way. Raymarine Tech Support recommends that you run the backbone cable to the pod, then connect to the spur cables via the connectors.
It was much easier to run one cable up a leg of the pedestal guard than four but that is a possible solution I'll consider.

Here is the text from the manual about the ferrites:
"Your product is supplied with a cable ferrite. To
ensure EMC Compliance, the supplied ferrite must
be fitted to the cable."

I think I'll try removing the ferrites, testing the system as suggested above. If all works well I may become a EMCC rebel and leave them off.
 
P

Project_Mayhem

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Sep 24, 2018
2,588
O'Day 25 Chicago
In all my years of running 100+ feet of cabling in different event spaces with thousands of different equipment configurations I've only seen ferrites make a noticeable difference a couple of times. Chances are you'll be fine without it
 
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