Transducer Cable Need Insulating?

[cbadmin]

From: C-Worthy (Original Message) Sent: 10/20/2003 10:24 AM
My transducer cable currently runs along one of my main power wires directly from the battery. I was reading that this is a no-no due to electrical interference. You'll probably not be suprised to hear that my sounder is giving me problems.

My sounder is not giving me a bottom profile or "white line" and I just get white noise throughout the screen (though the depth reading appears to be accurate).

My question is what material could I use to insulate the transducer cable? It is pretty tight in my cable pass-throughs, so it would have to be fairly thin material.

As you've probably seen from some of my other posts to this site, I'm not exactly Mr. Electric if you know what I mean (my battery isolation switch just about locked my brain into "off").

Any electricians/electronics gurus out there that could give me some advice on this?

Many thanks,
Blain
C-Worthy

Let the winter games begin....

From: MichaelOnTheClaraMae Sent: 10/20/2003 11:29 AM
Blain, I too am "electrically challenged", however, if it is interference you are trying to correct, I would think the wire would have to be shielded and not just insulated.

To be sure it is interference that is causing your problem, I would run another temporary line to your transducer away from your power lines and test it if you have not already done so. I am sure we will get some more help here on what to do.

Michael

From: Sawdust Sent: 10/20/2003 11:37 AM
Baine,

Les is tired from a loooong road trip from Denver -- so I'll just give you my take. He'll probably come up on line when he's back to human. Man, 2 days on the road and 1,000 miles in 24 hours sure seems to bother over-50 guys.

If there is a way, the easiest solution is to reroute the transducer cable. The transducer usually comes with lots of extra length for our little boats, and if your run is close to power or signal cables you will get interference. First, check to make sure your shield in the transducer cable is properly grounded. There used to be a lead shield available that could wrap or slip over the cable, but I'm not current.

HTH,

Dusty

From: C-Worthy Sent: 10/21/2003 10:19 AM
Thanks for the replies. At least I know I'm not too nuts. This gives me some food for thought. I like the idea of trying it out with a shunt to see if it really is interference. I'll let you all know if it worked in the Spring. She's put to bed for the year.

Unless sonar works in snow....

Blain
aka C-Worthy

From: C-Worthy Sent: 10/22/2003 6:15 PM
Well I took the unit out of the boat and plugged it into my computer. Set to "Simulator" mode it still displays no bottom, and a bunch of noise in the water column. I guess this means the unit's got an issue.

Back to the maker she goes. But I'm still going to wrap my transducer wire. Figured it can't hurt.

Blain
C-Worthy

From: stevej Sent: 10/22/2003 7:57 PM
Blane couple of thoughts
Have you tried turning down the gain or sensetivity settings until you get a clean screen?
With everything on the boat shut down but the sonar is there a problem?

Would not think having the transducer run along the main power feed would be a problem. Your dealing with 12 volt DC system and interference is due to the collapsing of the magnetic field created by current flow in a wire Yada Yada Yada AC or digitial communications have the biggest problems.
So the main power feed would only collapse it's field when turned on or off and I doubt that your cycling the switch while testing the sonar. Now it would be possible for the sonar to induce interference into the main power feed but it would be so small that it not worth considering.
Wiper motors could be a problem but I run my sonar along the main power and by my wipers with no problems. The transducer cables I have seen are coax and very well shielded by design.

Try this
Frist grounding make sure that the system ground for the sonar is terminated directly to the main ground buss (main grounding point on the wiring pannel)
Check the connections and make sure all are correct and tight from the transducer to the display. Check the cable run to make sure it's not pinched alond the way and inspect the cable for nicks or cuts.

Other than the above you may have a bad unit.

stevej







From: Sawdust Sent: 10/23/2003 8:52 AM
Steve,

All good points. Highly unlikely that the interference is coming from bundle -- but it does happen. Eye surgery by email is tough -- Manufactures recommend not paralleling or bundling transducer cable with other wires -- do it all the time and get away with it except for high powered commercial installations. I'd suspect poor grounding or something else in the boat. Easy to start from zero -- nothing on in the boat, engines shut down, and bringing stuff online one thing at a time.
Assuming (that's a bum word, eh) that the unit performs as desired with everything else off -- easy from there. The DC from motor alternators isn't exactly DC -- and can cause interference by inductance from the expanding/collapsing field if operating the depth sounder at max gain. Rare problem though, particularly on late model outboards. Common problem with inboards, which require condensers and chokes...

Dusty

From: stevej Sent: 10/23/2003 7:28 PM
Dusty good points the ignition system and alternator produce the most noise of any of the systems on our boats. Good grounding is so importent with low voltage systems and can casue all sorts of odd problems you just can't over state the point.
In my work problem isolation is done with "biniary logic" oh thats impressive.
Like you say shut down everything see if it works then start turning things on one by one until it breaks.

stevej