Stopping Radio Interference (1 Viewer)

[JeanLuc]

Some advice from vehicle electrics experts please.
The SOG motor on our van causes radio interference (standard FM radio). Can I simply fit a 1 microfarad capacitor across the terminals next to the motor, or is it more complicated than that?

 

[tonyidle]

Use a 0.1uF capacitor across the feed as close to the motor as possible (inside the motor housing). It needs to be there because any wire between the motor & capacitor will still act as an aerial to transmit interference. An easier alternative that will be almost as effective is to slip a ferrite sleeve over the feed where it enters the motor. If you have an old wall wart PSU with a moulded bulge in its wire you can cut the ferrite sleeve out of that - otherwise they are readily available.

 

[JeanLuc]

Thanks Tony. Does the ferrite sleeve go around both pos and neg cables, or just the pos?

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[Jaws]

Ferrite would normally go round both
Ideally the wire should go through the ferrite ( ring ) and be would round and back through at least once

 

[Mike800966]

I had the same problem with the SOG Fan and I just fitted 0.1Mf, make sure that it is at least 50v working- 100v would be better across the motor , since its a VHF problem then the ferrite will also help as it will act as a block to the higher frequencies
Mike

 

[JeanLuc]

Many thanks all. That will be a job for the near future once I have fitted the new window locking strips that arrived this morning!

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[Hettie's Crew]

Not the same, but related.
We are in Normandy/Brittany area and have been able to listen to Radio 4 on LW very clear until surrounding campers crank up their dishes, then it's just loud buzzing, and we resort to local French radio.
Is there any way to protect your signal in such circumstances?
Maybe a really good aerial?
I don't what sort of aerial we have apart from a cheap looking one stuck on the side window that is supposed to do Digital.

 

[funman]

Another question about radio interference, in our la Strada Regent MH:
I get interference on long waves when engine off, ignition circuit off, leisure circuit off, radio powered by separate car battery and aerial for testing. As soon as I take the aerial away from the MH, reception is perfect, so it can't be my neighbour's drill or whatever. The only things I can think of are the solar controller or a Battery Master which previous owner must have installed (God knows why). The interference is much reduced after dark so it could be the solar controller switching itself off, though maybe it's just the ionosphere going lower or higher or whatever it is, as it does every night, thus giving a stronger radio signal. Any ideas what the culprit might be, or what I can do? We like to listen to radio 4 in Greece like we used to do in the old camper van!

 

[funman]

Not the same, but related.
We are in Normandy/Brittany area and have been able to listen to Radio 4 on LW very clear until surrounding campers crank up their dishes, then it's just loud buzzing, and we resort to local French radio.
Is there any way to protect your signal in such circumstances?
Maybe a really good aerial?
I don't what sort of aerial we have apart from a cheap looking one stuck on the side window that is supposed to do Digital.

Have you tried connecting a longish wire to your aerial, slinging it up in a tree then across to another tree, in such a way that it points towards Droitwich (near Birmingham)? We've uses this ruse many times all over Europe and it often works to increase the signal, though it may increase the interference from your neighbours too I suppose...

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[Mike800966]

I wouldn't worry too much about which way the Long Wire aerial points but if you had a choice it wants to be at right angles to Droitwich UK. The signal strength will tend to increase after dark, like Radio Luxembourg on 208m MW used to do- showing my age now!

I think that quite a few electronic systems in modern vehicles do not necessarily shut down as the ignition goes off but remain waiting to see if they are needed again. Hence the high noise level close to the vehicle
A mechanic friend was telling me about BMW's who, as soon as the door unlock code is detected, they pressurise the fuel pump so as to ensure an instant start!
Also the digital side of most car radios is far from quiet, not being designed for weak LW signals.
When we were down in the Algarve for several winters, you could hear the start of PM on LW at 1700 but never the six o'clock news as the ionosphere changed the skip distance also changes. That was just on the internal Ferrite rod aerial.
Mike

 

[JeanLuc]

An update on the SOG radio interference issue.

First I tried the ferrite tube option as suggested but that made little or no difference. Then, yesterday, I bought a ceramic 0.1 µFd capacitor (100V dc) from Maplins for the princely sum of 9p. It took me about an hour of fiddly work to make a small cut in the insulation of the rather thin cables feeding the SOG motor and solder the legs of the capacitor in place; then I had to insulate the legs and protect the whole assembly behind a small plastic box with cable cut-outs, screwed to the Thetford door.
Success there is no interference on most channels and perhaps only the suggestion of some slight noise on R4 but I think that is because R4 reception is not very good in the van's position on the drive.

Many thanks to all who gave technical advice