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Old 09 May 2014, 20:38   #21
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Originally Posted by Festinghouse View Post
That was quite witty for you col, but yes, rather unhelpful! As for cables, i thought it was only ac not dc that caused interference?
Ok Jon, I deleted my earlier attempt at humour and admit it was my bad! A bit of bedtime reading on VHF issues has however turned up some 'more helpful' suggestions.

Apparently if the antenna is mounted too close to the microphone not only can it cause background noise on transmission (rf feedback?) but if the users head is within 1m it can also destroy brain cells......!

Also a bad negative can be the cause of additional noise, as can a low battery condition. The OP didn't have his motor running when he transmitted so perhaps this contributed to the problem.

I seem to remember he has also suffered with bad wiring on previous occasions (GPS Fuse and nmea?) so perhaps there is an inherent and unresolved issue here?

So there's three suggestions that might help explain what's wrong here and hopefully make up for my earlier faux pay.
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Old 10 May 2014, 04:17   #22
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The gps inline fuse problem was Resolved by taking it out altogether and direct + wire to fuseboard with it's very own 3amp spade fuse, the gps position signal to vhf was sorted very easily and was my dumbness of thinking it would still work without my mmsi number keyed into VHF , once this was done it found itself fairly quickly.
Maybe need to re-jig wiring so vhf cable away from other power sources etc
Is there a percific place to attach the ferrite????
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Old 10 May 2014, 04:24   #23
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My understanding is that the ferrite should go over the power cables, fairly close to the radio, if possible. The power lines can sometimes act as antennae (introducing noise) and this is what you're trying to prevent.

However, I suspect that if your electricity supply isn't 100% in the first place, ferrite magnets won't have much impact.
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Old 10 May 2014, 05:23   #24
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Coax can go bad or poor quality which could give background noise. If you can try another aerial and coax to see if that eliminates the noise.
Good luck
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Old 10 May 2014, 05:26   #25
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Aerial was brand new glowmax , can only think from surfing net is that cables close to main power cable etc and drawing noise via this with everything being in close area
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Old 10 May 2014, 05:41   #26
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It would help if we knew what the background noise was like - crackling, buzzing, high/low pitch/
Like mentioned earlier if you can get someone else with a radio or scanner so you can listen to the quality of your transmission that might just help us to point you in the right direction.
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Old 10 May 2014, 06:06   #27
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Yeah that is defo my next step and take it from there
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Old 10 May 2014, 12:13   #28
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One test to isolate the problem could be to disconnect everything else and temporarily wire the VHF directly to the battery and gradually put the other equipment back.

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Old 10 May 2014, 12:22   #29
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Should the vhf be direct to battery? I've rigged it up so it's wire to fuse board
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Old 10 May 2014, 14:35   #30
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The manual for my Lowrance VHF shows it connected directly to the battery, but I don't think there are any rules for leisure craft . It may be nice, however, to have an operational VHF even if the electrical system is shorted/burned out. I too have it connected to a fuse box, but I am contemplating the installation of a (small) separate battery for the radio and instruments in my RIB...

Geir
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