Fishfinder/VHF interference

[Beernutz]

I get an interference spike thru my VHF every time the Fishfinder transducer fires. It's a center console boat with Raytheon L470 fishfinder, Standard Horizon Intrepid VHF, and 3 ft base loaded Shakespear antenna on top of a 2 ft extension mounted to the highest point of the rail above the console (no t-top). Fishfinder is mounted on top of console, and is 3 ft from the base load of antenna. Space is limited, so the antenna wire is about 1 ft from the transducer cable at its closest point, but I've run them all over the place to keep them as far apart as possible everywhere else. Can't separate them any more than they are.<br /><br />Question: Is the interference coming in thru the antenna or thru the power wiring? If it's the power circuit, how do I isolate it?

 

[ungodly]

Re: Fishfinder/VHF interference

Beernutz:<br />I get the same interference, but my VHF is a handheld, which leads me to believe the VHF antenna (in your case, antenna cable) picks up the electrical noise from the xducer. My fix is obviously easier than yours, though. Good luck!

 

[snapperbait]

Re: Fishfinder/VHF interference

Beernutz: Your problem probably lies in the power wiring..Check out www.consumersmarine.com They have noise filters by NEWMAR that should take care of your interferenece problem.. Take a look at models NEPC10 and NEPC25..

 

[Boatist]

Re: Fishfinder/VHF interference

Beernutz Problem can be either in my case main problem was from antenna not power. Before you spend a lot of money on filters for the power try hooking your unit to a different power source, like a second battery in you boat your truck battery or a battery charger. In my case I tried a couple ham radio filters on both the radio and the depthfinder and it maid no difference. Three turns around a simple ferrite beed did as much good. I contacted my depthfinder manufacture and the said the problem comes form the unit it self and they were trying different shielding and would let me know when they found a solution. They also suggested not running power or transducer wires along side antenna wires. They never did get back to me and in later years did not even admit to knowing about the problem. I sent them a copy of the letter where they told me what they were doing to try and correct the problem but they never responded. In my case only affected channel 72 and 73 so I just turn thoese channels off. Good luck and if you find a fix please lets us know.

 

[Beernutz]

Re: Fishfinder/VHF interference

Thanx for the advice, guys. I didn't get much help from the manufacturers either. Just told me to refer to the installation manual. I don't have enough boat to do all that stuff!

 

[allanwh]

Re: Fishfinder/VHF interference

As the chassis of the sounder 470 is plastic it is not possible to ground the chassis for noise suppression therefore it may pay to ground the chassis of your radio and suppress the noise from it. Generally the antenna cable will be shielded and should not give you any noise problems....