Electronic Gurus...?

[fish factory]

I have a TOKIN ESD-SR-15 that came with a Furuno 600-L. I never found what to do with it. Looks like it might be a RFI choke, or a toroidal core for frequency range up to 300Mhz (found this on a "search&quot What is it, and what is its' best use?

[pbruce66]

You're right, it is a choke. According to the manual you should have one on both the power cable and the transducer cable. It's not the end of the world if you don't but it is a good idea to have them.