interferance on fish finder

[kreinhart]

hello, I have a 93 Aquatron center console with a 4.3 merc installed a Lowrance HDS7 and I'm getting a lot of engine interference when I try to pick up speeds above 1.7  should I run finder off a separate battery or is there a filter I can get?   thanks for any help

[ontherise]

Make sure the transducer cable isn't touching any other wires, I had this problem on my boat.

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[Chas0218]

Make sure the transducer is not mounted near a rib in the hull, that will cause turbulence and not allow the transducer to work correctly.

 

Also is it rpm induced? For example if you put the boat in gear but raise the motor rpms does the interference get worse?

Edited February 27, 2014 by Chas0218

[kreinhart]

yes it seems to be RPM induced

 

[BigMac]

Sounds like a ground issue potentially. Rpm rev puts alternator higher output and may have trouble if not grounding properly.

[Chas0218]

Make sure the connections on everything are tight. See if you can move the transducer cable away from the positive and negative leads.

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[Has Been]

New Plug wires

[Chas0218]

New Plug wires

I forgot about that.

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[Sk8man]

Perhaps resistor type plugs as well? Make sure your transducer wire is not co-mingled with the power wire or other power wires and that the power wire for the depth finder is away from other wires or sources of interference (e.g.engine power source). Try turning down the gain to check for turbulence induced interference (screen "noise") vs. electrical interference. They usually look a little different but not always.

Edited March 1, 2014 by Sk8man

[Chas0218]

Also you could try adjusting the noise filtration of the unit. That might help.

I would first run resistor plugs then look into the noise reduction.

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[Broadhorizons]

You could also shield your ff wires. get the foil tape for HVAC and use it to insulate your power and transducer wires. Run the tape down the length of the wire and roll it around the wire.

I would start with the resistor plugs and wires though. Turning the gain down might help also. On my Humminbird 958, I had trouble at first but was making the ff "look too hard" by having the gain higher than I needed.

[L&M]

 Turning the gain down might help also. On my Humminbird 958, I had trouble at first but was making the ff "look too hard" by having the gain higher than I needed.

 

 

[fathobbit0074]

If all else fails run a separate line just for fishfinder from bat Make sure to use an inline fuse

[ray koziatek]

try it with your engine off ,if that works install dual oar locks