Lowrance hook 7 causing interference on vhf
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Forum Name: Tech Topics
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URL: https://www.fishing.net.nz/forum/forum_posts.asp?TID=123232
Printed Date: 03 Feb 2026 at 11:10pm
Topic: Lowrance hook 7 causing interference on vhf
Posted By: swivelfish
Subject: Lowrance hook 7 causing interference on vhf
Date Posted: 05 Feb 2017 at 12:29pm
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I have a lowrance hook 7, when i have the sounder-transducer on 200khz or high chirp, I get a very heavy buzzing thru any vhf channel i am monitoring or using, i have to change to 'maps' or turn the whole unit off to even broadcast... Radio is on its own seperate power source (seperate battery), aerial lead is away from electrics, and i have tested a new power cable, which made no difference. Radio is over 1 m away from aerial. Aerial has been checked for seals etc and is ok. If i switch to 50khz, then the buzzing stops....has anyone had experience with similar issues or have a possible solution? driving me crazy! TIA. |
Replies:
Posted By: Steps
Date Posted: 05 Feb 2017 at 1:22pm
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Bit strange.. initially was thinking maybe some sort of inductive freed back.. but isolation of circuits sort of eliminates it.... Common grounds? 100% sure the VHF aerial and aerial wires dont have a broken/ or breaking connection somewhere? The co axle cables havnt been kinked/ damaged at all.. VHF and sounder... Rather strange... |
Posted By: swivelfish
Date Posted: 05 Feb 2017 at 2:18pm
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thanks for the input. It's certainly an odd one...seems like some weird frequency thing. Set up is less than 2 yrs old |
Posted By: MacSkipper
Date Posted: 05 Feb 2017 at 3:03pm
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I had a problem (please listen sort of relevant maybe?) where my digital tacho was resetting when fish finder on - eventually I tracked down to 12V supply for tacho came from 12V switched by engine key at remote control box - whereas fish finder power came from battery master switch - once I took power for tacho from fish finder problem went away - I think there was a ground loop issue as slight impedance on ground back to battery via control box.So anything been changed and since then? Or is problem present from new? As steps suggests check radio aerial connections - ground wire (shield) can break easily at either end or signal wire or could be corroded particularly at base of aerial - check continuity of cable - ie ground of case connected to base of aerial etc with multimeter. Reproduce problem at home on trailer ie fish finder on, radio on I assume happens whether engine running or not? Or only when engine running? Then try changing (temp hookup) power to fish finder or radio (whichever not already tried or both) direct from battery and see if problem goes away as interference maybe from other devices or ground . Does a handheld VHF or FM radio pickup interference in boat as well? ------------- Good fishing trip nothing breaks, great trip catch fish. |
Posted By: swivelfish
Date Posted: 10 Feb 2017 at 5:34pm
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All good advice...i can get the error to work on the hard, but it is worse at sea. I might even change the lowrance power source..as u suggested..got nothing to lose at this stage, thanks! |
Posted By: swivelfish
Date Posted: 19 Feb 2017 at 1:59pm
| So..i fitted inline ferrite things to power and transducer cables..no change...took my handheld on board, it too picked up the interference especially when switching from 50 to 200khz. I am Testing on the hard using weather channel to monitor...anyone got any recommendations for a marine tech who knows his stuff in auckland please?! |
Posted By: MacSkipper
Date Posted: 19 Feb 2017 at 4:55pm
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Sorry don't know anyone in Akld - but it does sound like issue is with Lowrance unit or its transducer if handheld is picking it up too (not radio in boat) - try contacting Lowrance service agent in Akld? Mention you are concerned as a safety issue interfering with radio? Ideally to try another head unit (display box) would be easy if they have one? If not head unit then you have cabling of power or transducer - you could then try running head unit from another battery/cable but as only on 200khz I wonder if head unit or damaged transducer/cable. Does anyone here in Akld on this website have the same unit and you could visit them and try swapping units etc? Maybe try listing with that title and explain if Lowrance can't help?
------------- Good fishing trip nothing breaks, great trip catch fish. |
Posted By: out2sea
Date Posted: 20 Feb 2017 at 10:05am
| I had a similar problem with my Elite 5 Chirp was causing interference on my hand held vhf. Never sorted it out but there was no interference when sounder was switched off. |
Posted By: MacSkipper
Date Posted: 20 Feb 2017 at 11:34am
Yes you could live with it, problem is if going out wide and doing trip reports you want to have your radio on all the time. I would hate to be crossing bar and having to adjust fish finder turn radio on then off before and after crossing - just one more thing to think about. ------------- Good fishing trip nothing breaks, great trip catch fish. |
out2sea wrote:Posted By: Steps
Date Posted: 20 Feb 2017 at 12:22pm
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but there was no interference when sounder was switched off.
To me that sounds like a shielding issue in the transducer cables/ and or some sort of feedback ... Maybe try a different transducer and cables? I have an elite 5 chirp no issues at all... Both , and everything else (nav lights, pumps etc) go back thru each individual dash switch/ fuse to main power from battery and common buzz bar for grounds. |
Posted By: swivelfish
Date Posted: 12 Mar 2017 at 9:15am
| Thanks for the feedback, its somehow encouraging that at least one other person has had the same issue..phew..i think it might be worth calling navico here and see what they say.... |