Fish Finders/Sonar units can cause RFI “noise” in other electronic devices on a boat including audio and video systems, radar, SSB, wind/speed/depth instruments, etc. Likewise other electronic devices can also interfere with the fish finder and cause erroneous depth/temperature readings.
Palomar Engineers has developed a simple to install fish finder/sonar RFI suppression kit to solve the RFI noise problem aboard recreational and commercial boats.
Here is an example of typical installations on a simple fish finder/transducer pair (click picture for larger image):
 Transducer Filter and DC power Filter |
 Transducer and RFI Snap On Filter |
Kit includes 2 large RFI filters with 1 inch hole and another with 1/2″ hole for the DC power. Typical installation pictures and instructions.
Part # RFI-FF Price $45
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Tech Note: For multiple transducer fish finder/sonar units add a pair of FSB31-1 snap on filters for each transducer – 1 at the transducer and another for the transducer cable to the readout. Price per pair is $37