Interference on a Defender 90:(

4x4 CB radio advice and troubleshooting

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hovis_211
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Mon Aug 01, 2011 4:06 pm

Hi Im kinda new here so go easy please :)

I just swapped my Midland CB radio out of my series 3 to my 90. Im getting loads of interence with the engine on and it gets worse with speed. So being a diesel im guess its not points or dissy. So i think its the alternator? Is there a way to get rid of this?

At the moment im straight off the battery (with a inline fuse). I also have good SWR readings.

Hope this is enough information.

Thanks :)

joe jeep
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Mon Aug 01, 2011 4:08 pm

Where abouts have you got your antenna mounted, and are you powering your radio direct from the battery or elsewhere?
Handle:Joe-Jeep
Location: Littlehampton, West Sussex.
On either UK19 or if you cant find me there try UK26.

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stampman
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Mon Aug 01, 2011 4:51 pm

if it is a whine that gets higher as yo race the engine then it is most likely the altinator



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hovis_211
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Mon Aug 01, 2011 10:17 pm

Hi
It is powered straight from the battery and the aerial is at the back on the gutter With a good earth.

The noise does get worse with the engine reving higher. So my guess is the alternator. Is there some way to reduce the interence from this?

Thanks

Offplanet
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Mon Aug 01, 2011 10:34 pm

Like Stampman said, if it's a whine that varies with engine speed, it'll be alternator noise - suppressors are available that fit to the alternator or an inline filter in the power lead to the CB can help (listen if the noise goes away when you unplug the aerial - if the noise is still there, the interference is likely to be coming up the power lead).

If the noise is a crackling or popping sound that varies with engine speed, it could be the diesel injectors - I had the same problem with my van. I tried everything, including adding extra earth wires to the radio, bonnet, exhaust, doors - helped a bit.

In the end, what really cut it down was adding ferrite rings to the injector wires - the clip-on type ferrites didn't help much but these big ring ones really helped :wink:

Try the easy stuff first though

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porky.69
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Sat Sep 03, 2011 9:07 pm

stampman wrote:if it is a whine that gets higher as yo race the engine then it is most likely the altinator



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stampman
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Sun Sep 04, 2011 10:28 am

i thank you now to do the euro millions drinks on me if i win


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