Optimax Radio Interference

[oldboot]

firsly we need to understand that 27Mhz marine is AM ( amplitude modulated ) and VHF marine is FM frequency modulated.

FM by its very nature has far greater immunity to inteerferance and AM.

Any radio signal that is AM is very prone to interfeerance and regardless of best efforts sometimes it is hard to solve an interferance problem

BUT
Other manufacturers seem to manage.

The problem with the EMCFW, is that there is a strong requirement to comply, but there is no widespread enforcement of compliance and it is almost copmpletely self administered.
The only time you will get busted is if there is a complaint......in the last few decades inforcement of radio interfeerance has been pretty piss weak.

with these new electroniclay injected motors there are now 3 major sources of possible interferance.

the ignition system
the charging system
and now
the injection system

motor manufacturers have been strugling with interfeerance from ignitions and charging systems for decades, so the methods have been pretty common knoweledge.

Evenrude these days are a 1 trick pony and simply do not have the wide engineering resources and experience of the car manufacturers....so they may not have come up with a solution.

we dont seem to be hearing of similar problems from suzuki, honda and yamaha.

I would be interested to see where the electrical noise is escaping.....is it radiated in free air or is it escaping via the cables comming out of the powerhead.

either way there are pretty standard methods that could be used to solve the issue.

some of them as simple as putting some sort of metalic material in the plastic the motor shoud is made off or just coating the inside with shielding paint.

In this day and age I am disapointed that such this are still a problem.

cheers

[Daisy Burnett]

The bottom line is that very few dealers or manufacturers have qualified people install electronics in their boats.

This matter gets even worse when they try to fault find.

Something that would stick out like dogsballs to anybody semi-qualified simply looks neat and tidy to these guys who may have genuinely tried their best..

I work in Sound, lighting and AV, no amount of professional hand holding can help someone who simply cant see.......I have tried to talk customers thru stuff to no avail.... turned up on site and fixed the problem without even opening my tool box.



when it comes to electrical and electronic cabling there is no substitute for hygeen and seperation.

This is one reason why the current communications cabler's rules forbid ( in several ways) tying comms cables to any other service.


It does concern me that the motor is allowing RF noise to get into the cables though.

We have had the "electromagnetic compatability framework" in place in this country now for over 10 years, that requires a certain amount of immunity from radiating electrong noise from all electronic devices.

It might be worth checking that the motor and the negative of the electrical system IS solidly bonded to the hull at some point (preferably one point)......with most boats this occurs at the motor mounting bolts..... but that can easily be dodgy.

other things not withstanding...it might be worth whacking a couple of big frerite beads on the electrical cables comming out of the motor.....this may help block the escape of RF noise into the cabling.


cheers

Old boot
Some wise words there. One thing. What are these ferite beads? Where would I look at sourcing some and how are they fitted?

Cheers
Daisy

[cormorant]

Jaycar , tandy , dick smith if they still actually stock small parts

Cheap and possibly worth a try on all wiring . In theory aerial coax is shielded but..

There are many different sorts and sizes In case it is being induced along the cable run it may be better nearer the unit but trial and error with these things on whether it is on the radio power wires or the engines harness.

http://www.jaycar.com.au/productView...e&form=KEYWORD

[oldboot]

ferite is an iron loaded ceramic...... crudly a whole pile of iron fileings stuck together with glass.

Ferite is used because it has ( well can have) better high frequency performance than solid iron.

These things are basicaly tubes of the stuff in various sizes from very very small to as big as your fist.

They pop up on all sorts of cables these days, in practice, they just look like a heavy lump that the cable runs thu, sometimes covered in heat shrink or moulded over in plastic.

Have a look on the VGA cable going to your computer monitor there is a pretty good chance there is a cylindrical lump bear the ends...that is a ferite bead.

They work on a couple of basis.

sometimes electronic noise travels IN the wires comming to and from an item ( wires are an oportunity for escape)....in this case the wires may be run thru the bead a couple of times..this presents an inductance that supresses or block the noise ( makes its path harder). mostly lower frequencies.

sometimes the electrical noise travels on the outer surface of the wires....this is stuff up in higher frequencies ( where things get weird)......the bead in this sort of target is usually snug on the jacket of the wire or snug on the braid. The bead in this situation serves again as an inductor but it works like a big speed bump or a ledge that the stuff traveling on the outside of the wire runs into......it will also have an inductive effect inside the wires.

The above represents the best explanation I can manage for non technical types........the real engineering reality of how it works is very complex & even I don't need to understand it to make it work.

so depending on what you are targeting and what your wires look like.
If its a big cable like a VGA cable o such with a coax or lots of wires in it.
You buy a largish bead that will be split for convienience you simply put it on the wire and either use the clamp provided or some other means to hold it there.

If you are looking at individual wires you can slip individual smaller beads over those wires and cover them with heat shrink to hold them in place.

If you have a large problem they may not help much, but for mopping up annoying residual noise they may help.

Mostly they are applied these days as a simple easy precaution by manufacturers.

cheers

[Daisy Burnett]

firsly we need to understand that 27Mhz marine is AM ( amplitude modulated ) and VHF marine is FM frequency modulated.

FM by its very nature has far greater immunity to inteerferance and AM.

Any radio signal that is AM is very prone to interfeerance and regardless of best efforts sometimes it is hard to solve an interferance problem

BUT
Other manufacturers seem to manage.

The problem with the EMCFW, is that there is a strong requirement to comply, but there is no widespread enforcement of compliance and it is almost copmpletely self administered.
The only time you will get busted is if there is a complaint......in the last few decades inforcement of radio interfeerance has been pretty piss weak.

with these new electroniclay injected motors there are now 3 major sources of possible interferance.

the ignition system
the charging system
and now
the injection system

motor manufacturers have been strugling with interfeerance from ignitions and charging systems for decades, so the methods have been pretty common knoweledge.

Evenrude these days are a 1 trick pony and simply do not have the wide engineering resources and experience of the car manufacturers....so they may not have come up with a solution.

we dont seem to be hearing of similar problems from suzuki, honda and yamaha.

I would be interested to see where the electrical noise is escaping.....is it radiated in free air or is it escaping via the cables comming out of the powerhead.

either way there are pretty standard methods that could be used to solve the issue.

some of them as simple as putting some sort of metalic material in the plastic the motor shoud is made off or just coating the inside with shielding paint.

In this day and age I am disapointed that such this are still a problem.

cheers

Old Boot
Mate thanks for that info. Now that you mention the beads being on a computer cable I do know what you mean, I just never knew what they were. I will definately give them a try. Thanks again for the great info.

Daisy