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Can other wires cause transducer interference?

Old 10-06-2008, 08:28 AM
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Default Can other wires cause transducer interference?

I just installed a new P66 transom mount transducer on my small aluminum boat in hopes to get a better depth reading while on plane than the previous units that I've tried. I did a quick test in the lake near my house and it worked perfectly even though it was very rough on the water that day. Yesterday I went fishing in the marsh with it and it didn't perform nearly as well (kept losing depth signal). What I am wondering is this....When I did the test run, I didn't route the cable under the deck with all of my other cables and wires. I just had it draped across the deck in case it didn't work I wouldn't have fished it through for nothing. When I took it fishing, I had routed the transducer cable under the deck in the cable tunnel with all the other wires. Could the other wires have caused "interference" of some sort with my signal by being routed along side them? This may be a stretch but when my GPS and VHF were originally installed (on a different boat) the wires from each unit were too close and would cause a failure when both were used.
thanks
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Old 10-06-2008, 08:40 AM
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Default RE: Can other wires cause transducer interference?

Most transducer problems are related to the angle of the transducer or cavitation air bubbles. Because you're in a small boat, I suspect that the angle (pointed down) of the transducer changes quite a bit while underway, or stopped. You'll have to make adjustments in the transducer mount to find a good compromise of angles. You should get a good picture on your sounder while cruising at slower speeds, (searching for rocks)

Once upon a time, I put a large lure on my fishing line and ran it down on different sides of the boat. I found that my transducer was pointing to the starboard a fair distance. (I could see the lure on the starboard side, not the port). I made adjustments on the transducer mount and the next time, I could see the lure when it was directly under the boat.
'
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Old 10-06-2008, 11:37 AM
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Default RE: Can other wires cause transducer interference?

Hooked1 - 10/6/2008 8:28 AM

I just installed a new P66 transom mount transducer on my small aluminum boat in hopes to get a better depth reading while on plane than the previous units that I've tried. I did a quick test in the lake near my house and it worked perfectly even though it was very rough on the water that day. Yesterday I went fishing in the marsh with it and it didn't perform nearly as well (kept losing depth signal). What I am wondering is this....When I did the test run, I didn't route the cable under the deck with all of my other cables and wires. I just had it draped across the deck in case it didn't work I wouldn't have fished it through for nothing. When I took it fishing, I had routed the transducer cable under the deck in the cable tunnel with all the other wires. Could the other wires have caused "interference" of some sort with my signal by being routed along side them? This may be a stretch but when my GPS and VHF were originally installed (on a different boat) the wires from each unit were too close and would cause a failure when both were used.
thanks
Running wires parallel to each other will cause "cross-talk" or interference between items. Keep antenna & transducer cables away from each other. The tachometer cable is another cause of noise. Consider using shielded cable or you can install noise filters on your power cables. In extreme cases, rewire your powercables (picking up the interference) directly to your battery.
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Old 10-06-2008, 01:05 PM
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Default RE: Can other wires cause transducer interference?

So can this "noise" or "cross talk" translate into degraded signal reliability when running? Could that explain why it worked fine one day but not the next?


PS.
I don't want to turn this thread into a "transducer location" thread....been thru all that...but thank you.
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Old 10-06-2008, 01:36 PM
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Default Re: Can other wires cause transducer interference?

Short answer: yes.
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Old 10-06-2008, 02:00 PM
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Default RE: Can other wires cause transducer interference?

Hooked1 - 10/6/2008 1:05 PM

So can this "noise" or "cross talk" translate into degraded signal reliability when running? Could that explain why it worked fine one day but not the next?


PS.
I don't want to turn this thread into a "transducer location" thread....been thru all that...but thank you.
It could work fine when you just laid the cables out, but when you repositioned the cables they were closer to other wires. If you want to test it out...
1) shut off everything on the boat.
2) Turn on the depth finder. (you should have a clear display with no interference).
3) Turn on other devices - one at a time until you notice the interference.
4) Transmit on your VHF / CB radio - Did that cause interference?
5) Last but not least - start your engine.

Once you know the offending equipment you need to isolate the cable run. On most boats the majority of the cabling is run on the starboard side up to the help.
Try tunning your transducer up the port side to the helm. Don't tie wrap your transducer cable to the other wires. Last thing - don't forget your power cable to the FF might need to be isolated or get a noise filter from radio shack.
Hope this helps.
George
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Old 10-06-2008, 04:01 PM
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Default Re: Can other wires cause transducer interference?

I'd bet ya a million to one, it's not the "other wires". I have spoken to engineers at Airmar in the past at lenght on this subject. The answer is always the same, it's not going to be a problem unles you have a "leaky wire" (broken, damaged wire, faulty ground....). You can install a ducer directly under a motor, 6 inches away. Imaging the rf noise that comes out of there.....

BUt, that doesn't mean you should rule it out. It's just not likely. 999 out of 1000 times, it all about clean water under the transducer and it facing the correct angle (aka DOWN!).
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Old 10-07-2008, 01:49 PM
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Default Re: Can other wires cause transducer interference?

This is from Lowrance transducer installation guide...

http://www.lowrance.com/upload/Lowra...582_041703.pdf

"If possible, route the transducer cable away from other wiring on the
boat. Electrical noise from engine wiring, bilge pumps and aerators
can be displayed on the sonar's screen. Use caution when routing the
transducer cable around these wires."

Electrical noise is a definite possibility.
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Old 10-07-2008, 03:32 PM
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Default Re: Can other wires cause transducer interference?

Agree with Birdman. Most transducer cables are shielded, so even if you ran them right next to some unshielded AC cabling or something otherwise RF noisy, it shouldn't be a problem.

If your tranducer cable has a shield (braid, foil, etc) be sure it's grounded at the FF or cpu box, but you might have a cable with the molded on cable in which they already took care of it.

Could be reading noise from the power circuit as other posters mentioned, say the engine's charging circuit oscillating for some reason (dying rectifier diode?). Most of the mfg's techs recommend powering from standalone battery to isolate power issues, if you can't isolate from things by turning stuff on one at a time. If the poor performance continues, it's probably a transducer placement issue.

Good Luck
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