Sheild on Power Cable Question

Hightower · 20 March 2011, 16:14

I'm upgrading my electrics and Nav systems and have come across a sheilded power cable on a GPS/Depth finder.

Do I ignore this or just teminate it to earth?

ashbypower · 20 March 2011, 19:25

Hi Andy, I would connect to -ve may just as well use the shield as its there..

jyasaki · 20 March 2011, 23:58

Power shouldn't be too noisy, nor should it be particularly susceptible to picking up noise. Should be fine if you leave it unconnected, but also won't hurt to connect it to ground.

You do want to make sure the transducer cable is shielded to ground, though; the click pulses are easily transmitted to the VHF.

jky

Hightower · 21 March 2011, 00:29

I'll shield it to ground then. The transducer cable is all in one, so it'll already be grounded I hope

I had it running this afternoon on the trailer and managed to find the driveway though over a foot of air (I doubt I'll have any problems with air pockets in the hull

). Could even hear the clicks when stood at the transom.

Ian Austin · 21 March 2011, 01:08

Andy
If you do connect the screen to -ve only connect one end, as if you connect both ends you can end up with an earth loop which then amplifies any bad signals.

Hightower · 21 March 2011, 03:10

Thanks Ian, there was a take off already poking out the end of the cable, it'll be this that I'll ground. If I get any problems I'll disconnect this feed first.

jyasaki · 21 March 2011, 21:51

Quote:

Originally Posted by Hightower

I had it running this afternoon on the trailer and managed to find the driveway though over a foot of air

Out of curiosity, what was the reading? When my transon mounted transducer picks up the asphalt, it usually reads about 6 or 7 feet, despite being about 18" feet up. (Sound travels faster in water than air.)

Quote:

Could even hear the clicks when stood at the transom.

Spent about 5 minutes on a quiet lake climbing all over the boat trying to figure out what the faint but incessant clicking noise was.

jky

Hightower · 22 March 2011, 01:13

Quote:

Originally Posted by jyasaki

Out of curiosity, what was the reading? When my transon mounted transducer picks up the asphalt, it usually reads about 6 or 7 feet, despite being about 18" feet up. (Sound travels faster in water than air.)

Spent about 5 minutes on a quiet lake climbing all over the boat trying to figure out what the faint but incessant clicking noise was.

jky

Digital reading was 0, but the graph was showing about a foot. I was very impressed!

If we can hear the clicks though air, imagine what it sound like to a Dolphin.

jyasaki · 23 March 2011, 06:09

Quote:

Originally Posted by Hightower

If we can hear the clicks though air, imagine what it sound like to a Dolphin.

When I heard it, the transducer was a foot underwater (freshwater lake.) Drove me nuts til I figured out where it was coming from. I don't recall noticing the clicks with the boat on the trailer (though I haven't really listened for it, either.) My ducer is a 200KHz model.

jky