Eliminating noise in radio

[fishstix]

I need some help eliminating noise from my motor in my radio and fish finder. I have them both mounted on my console and get interference on both. I have checked all of my grounds and everything appears good. Is there a way to add an inline filter to supress engine noise and where do I find one?<br /> Thanks

 

[18rabbit]

Re: Eliminating noise in radio

There are two ways to filter noise in your power system. the preferred method is to filter the noise at its sources, the alternator. Placing the filer near the alternator’s output gives you clean(er) power throughout the whole system. The other method is to filter for noise at the instrument, just before the power input.<br /><br />How many amps does your radio pull? And how many amps does your ff pull?

 

[ndemge]

Re: Eliminating noise in radio

...18rabbit has a good point of filtering everything, except your trolling motor and battery, that's a lot of amperage to put through a filter.<br /><br />Radio Shack, "Ground Loop Isolator"<br /><br />I always have to use these in the car for stereo amps or CB usage, get that alternator "whine"

 

[i386]

Re: Eliminating noise in radio

I don't know if this applies here, but when wiring a car stereo I found that wiring the amplifier ground straight to the battery rather than to the chassis eliminated the engine whine noise.

 

[Yepblaze]

Re: Eliminating noise in radio

It would depend on the source of the noise.<br /><br />Is it the ignition system?<br /><br />Is it the alternator?<br /><br />Maybe just probe around the engine bay with a small portable am radio and look for it. It might be easiest to eliminate the source.<br /><br />Otherwise you could try running ferrite rings wrapped around all your different wires into and out of the units.

 

[briannh1234]

Re: Eliminating noise in radio

I second i386 advice. Best power filter you can get is a battery.

 

[mfarish]

Re: Eliminating noise in radio

Reading this makes me think of the old CB radio days and equipment, however, allmost all outboard engine rectifier circuits that connect to the battery have absolutely NO filtering of the DC supply generated by the altenator. You are at the mercy of the capacitors in the device you are hooking up to the 12VDC, which most of those devices (radios, depth finders) are lacking in this department. One of the best ways I have found to reduce noise is to add a large filter capacitor across the battery supply, large meaning anywhere from 500uf to a 5000uf value with at least a 50VDC rating, even better 100VDC.<br />Just remember, this capacitor will stay charged if disconnected from the circuit and can result in a very large, arcing, spark if the terminals are shorted accidentally. Very dangerous with GASOLINE if you catch my drift.........

 

[Philip Stone]

Re: Eliminating noise in radio

Depth sounders can pick up interference along the transducer cable. So that needs to be routed to the device separate from other wiring. I switched my transducer cable route so it runs a good 3ft away from any other wires and the difference in noise reduction was huge.

 

[jollymon]

Re: Eliminating noise in radio

Fishstix,<br /><br />I had the same problem with my boat. I was picking up both noise from the alternator and the depth finder. To fix the problem I moved the transducer cable away from the power cables from the battery. That solved the depth finder noise. The alternator noise, was solved when I ran two 6awg wire from the battery to the helm just to power the accessories, IE radios, fishfinder, gps etc... The 6awg goes into a fuse block and then to each device.<br /><br />good luck.