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YachtVALHALLA 03-12-2006 02:10 PM

Furuno Radar Cable Junction Box?
It was necessary to cut the signal cable for my Furuno Radar (Model 1720) to remove the mizzen mast. The cable was jammed and the crane was on it's way. The Owner's Manual says 'no splices allowed' but goes on to say ".. a junction box may be installed at the base of the mast, under the floorboards. (sic) The junction box must be watertight and the wire breakout must be kept as short as possible."

Has anyone done this?


Jack Tyler 03-12-2006 10:16 PM

Hey, Terry - ain't pulling the sticks fun!<g>

The 'junction box' approach is not that uncommon. I remember it was discussed regularly back when Raymarine was first issuing their new R70 series and hadn't yet offered a sufficient # of choices for extension some buyers of new sets had to do the same thing. I'm sorry I can't offer you a URL or two, but this has been discussed and illustrated on several websites I visited a few years ago (when we were installing the same system), so Google away. Also, check at the Raymarine website in the technical section. Unless I'm experiencing brain fade (which is always a possibility), it's also discussed there and the issues are the same independent of radar brand, I would think.

Thinking of pulling the sticks in Turkey next I'll be 'all ears' on what and how you proceed.

Best wishes,


YachtVALHALLA 03-13-2006 07:35 AM

Thanks for the Raymarine suggestion Jack!

It appears that either a junction box or splicing is OK according to Raymarine.

My concern has been that there is a small (very small!) coax in the bundle of wires. The schematic says it is a 'video' signal'. My concern was an impedance mismatch if it were spliced or joined with a connector. I conclude this isn't much to be concerned about.

A junction box will make it much easier to install the wiring from the scanner through the mast. There are two connectors (one 8 pin and one 10 pin) on my cable. When I installed the radar 16 years ago I had to disconnect the wires from the connectors to fit them through the hole in the mast, otherwise I would have to make a very large hole to pass the connectors through. So the cable was fed up the mast, through the hole in the mast, then the wires reconnected to the connectors. A pain to do but was the only was to keep from cutting the cable. Now I know better!

I won't know the result for about five months when it is reinstalled. Will let you know ... assuming my brain fade doesn't interfere!

BR, Terry

Jack Tyler 03-13-2006 07:58 PM

Terry, I'd recommend you consider putting together your junction box (as I recall, Blue Sea Systems offers some of these, as do other vendors...or you can build up your own) and then temporarily hooking up the radar array and fire up the unit while on the hard. Exercise the unit just as you would at sea to confirm the box functionality, leaving lots of time for troubleshooting before the Splash, if you find that's necessary. Good luck!


YachtVALHALLA 03-17-2006 06:50 AM

Since the masts are laying beside the boat and the components are stored away it will be difficult to do a 'smoke test' until things are back together. BUT ...

Good news! After convincing Furuno that it was stupid to forward my question to Japan for an answer (that was because I answered a question about my location being in Thailand, though I had purchased the radar in the USA) I have now received the following answer from Furuno USA:


Thank you for contacting Furuno USA, Inc.

Hello Terry,

Since the cable is already cut I would find and use a suitable splice for the Coax, the center wires are very fragile but what I find that helps is to solder or splice a larger gauge cable to the center coax and then take that to your terminal strip/junction box, the rest of the cables should be fine.


So now we all know the manufacturer's recommendation.

Thanks again for all of the replies.


Oscar 05-18-2006 02:33 AM

My $0.03

Bought a used Raytheon radar with a cable that was cut during de-installation.

Got a Radio Shack aluminum project box, a couple of screwclamp romex retainers from Home Despot, and a small bus connector strip (10 wire I seem to remember.)

Drilled holes big enough to fit the romex connectors in the box, mounted the box in a dry location, (ceiling of the engine room in my case) soldered all the ends of the wires in the two cables and connected them with the bus bar. Clamped down the romex connectors and put the lid on the box......

Works just fine.

YachtVALHALLA 05-18-2006 07:55 AM


Many thanks for the input.

I've made up the connector box and the terminals and am ready to install when we get to the stage of re-stepping the mast in a few months.

You've given me the confidence to scratch this one off the 'worry' list.

Cheers and beers,


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