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Discussion Starter #1
Hi guys,

Would any of you have any advice or experience of the following problem...

My fishfinder (garmin) interferes badly with both my fm stereo and more importantly my vhf (ICOM). I have tried re-routing all the cables from the transducer and power to each device so they dont run along the same paths, i even tried connecting the vhf to completely seperate battery and there is still interference. This leads me to believe that it isnt electrical interference, rather the vhf is picking up a signal transmitted by the fishfinder/transducer. it doesnt matter how much i squelch up it is still present.


Any ideas or help would be greatly appreciated as this is doing my head in!!


Ryan
 

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Very hard to track the cause down, just some ideas:

Is the coax cable soldered into the connector plug that screws onto the back of the VHF. Some types of plug are twisted on, the best type are the soldered on type where both the centre conductor and the braid shield are soldered.

There is a thing called a ballan, i think, it is a ferrite ring designed to snap together over the coax cable. These can help, fit it as close to the vhf as you can.

A corroded connection or a bad connection on the braided sheath of either FF or VHF can cause the signal to escape or be allowed in, but you have probably covered this with you saying you rerouted the cables.

You don't have a spare Vhf aerial you can try just in case the aerial itself is picking up the signal

Last thing to try is a bit drastic, wrap the length of transducer cable in a self adhesive foil tape and connect this to earth. You are in effect creating a new shield around the cable.
 

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Discussion Starter #3
I know its been a while since I posted this but the plot thickens...

I borrowed a hand held vhf and it also picks up the exact same interference when the fishfinder is on, both in the cabin and outside so at least i know now its not a dodgy vhf set and that the signal isnt coming through cables.

The boat beside me in the marina even picks up the interference!!

It does however leave me with a head scratcher!! It would seem the transducer itself is sending out a signal so next round of Q's

The FF is a garmin, is the connection between FF and ducer standard ie does any transducer work with this system?

Does it sound like a faulty transducer?

As I increase the scroll rate on the FF the ticking increases in speed.

Sorry to keep this one active - its just rather annoying, 2 important bits of kit not liking each other!!

Thanks
RYan
 

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I have come across this before, the ground on you transducer cable is faulty. The answer is to use a self adhesive foil tape to create a supplemetary ground. Get a length of foil tape and wrap it along the whole length of the existing cable, completely covering the cable. Finish off by wrapping the foil over 6 inches of bared wire and connect the other end to earth. Finish off by wrapping the lot in insulation tape to prevent corrosion if it works.

It really is difficult to track down but this has worked for me in the past.
 
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