can this cable be extended

[tim_ber]

The power cable from the radar display is too short to get to the power.

The cable consists of a thin positive and negative electrical wire, lots of padding and insulation, a braided (shield *)? wire and then really thick insulation.

(*But the plug to the back of display has 3 pins, so is the braid a ground? What is a ground, where should it go? Positive to positive of switch terminal and similar for negative, do I need to do anything with this braid?)

Can I make up the shortfall with ordinary cable or do I needed this special braided stuff? Can I use 'ordinary' 3 core?

Will make it very difficult to run the rest of way if I need 'proper' cable, also how do I join the braid?

I know with vhf co-ax the only way to connect wires such as this is via connectors and no soldering owing to braid losing impedance etc.

What is the briad on the cable?

It is only the power to the display after all.

Thanks in advance and ignorance.

 

[lw395]

That doesn't sound like a 12V power cable to me.
I'd suggest at least gving the make and model of the set.
Is it new?

 

[tim_ber]

Yes, sorry, Furuno, Brand new.
Looks like this:
http://www.furuno.fr/Produit.php?&Page=Produits&Produit=000.154.028

but only 3 pins and two conducting wires and the braid.

Manual states it is 12v cable (with inline 5 A fuse) but does not tell me how to extend it.

That doesn't sound like a 12V power cable to me.
I'd suggest at least gving the make and model of the set.
Is it new?

 

[LadyInBed]

In general, a cable can be extended by cutting it at a convenient point along its length, buying a length of suitable cable, 2 male and 2 female connectors. The plugs and sockets don't need to be the same as the ones on the ends of the original cable, they just need to be capable of doing a similar job. At worst, the connections could be chocolate blocks in dye cast boxes. The braid is just a screen to keep out interference, so could be connected to the case of a metal connector, a pin on a plastic connector, or the dye cast box if that is the route you took.

 

[john_morris_uk]

The power cable from the radar display is too short to get to the power.

The cable consists of a thin positive and negative electrical wire, lots of padding and insulation, a braided (shield *)? wire and then really thick insulation.

(*But the plug to the back of display has 3 pins, so is the braid a ground? What is a ground, where should it go? Positive to positive of switch terminal and similar for negative, do I need to do anything with this braid?)

Can I make up the shortfall with ordinary cable or do I needed this special braided stuff? Can I use 'ordinary' 3 core?

Will make it very difficult to run the rest of way if I need 'proper' cable, also how do I join the braid?

I know with vhf co-ax the only way to connect wires such as this is via connectors and no soldering owing to braid losing impedance etc.

What is the briad on the cable?

It is only the power to the display after all.

Thanks in advance and ignorance.

My best guess is that the 'braid' is a screen to try and stop stray electrical interference from the radar which has got onto the radars own power connection from being emitted and thereby potentially interfering with othe electronics in the boat. If this is the case you can check if its connected to the negative side with a meter set to ohms. (Make sure it's plugged into the radar; the connection will be internal. )

Your comment about not soldering the braid of coax in completely wrong. The impedence of coax is a slightly complex function of diameter of inner conductor vs diameter of the. 'cylinder' of braid and the dielectric properties of what separates them. It's only if soldering disturbs these factors that the impedence will change and at yacht VHF frequencies you've got to do something pretty radical to make any noticeable difference. Soldering the cable correctly and neatly is in general terms a good thing.

Back to your problem. One answer might be to just try extending the lead without a braid cover. It will either work or it won't. Otherwise you can find twin with braid cover from lots of places. The neatest way of connecting the braid is to very carefully bend the cable back an inch or two from the end and with a small screwdriver or similar ease the strands of braid appart and pull the inner cables out through the hole. You then end up with a tail of braid (that you can easily solder) and two wires. A simpler way is to simply comb the braid appart for the last inch or two and twist the braid wires together to make the same result. You don't need fancy connectors to extend the power line. Neat soldering and some heat shrink with tape over the whole thing would be perfectly adequate.

 

[tim_ber]

Thanks for the helps everyone.