Radio noise

[rovi]

I have fitted a cd radio to my caravan which works fine playing cd's but has a very bad buzz when playing the radio. When I switch off the mains power system ( the 12 volt transformer and charger ) the radio works fine. This is not an ideal solution as the fridge, charger and a socket are all on the one circuit.

The aerial is a Status electronic radio antenna which is powered from the radio output for a powered antenna and as I have already pointed out works ok without the mains power on.

It seems that some sort of suppression is required here but I am totally clueless so can someone who has more idea than me please help out.

Thank you.

 

[FatherTed]

The noise is probably not coming in on the aerial, but from the power. Try getting an in-line supressor for the 12v feed. Any car shop ( Halfords etc ) will sell them and they are quite cheap.

 

[Colinn]

...while we're on the subject guys...

...my Sony radio and CD player has a high pitched background noise - sort of high pitched whistle - that annoyingly my wife can't even hear!!

It's there whether radio is on or off (displaying clock) on both radio and CD. Drives me mad and the only way I can stop it is to remove the fuse...

Any suggestions on this one?

Tks...

 

[rob_jax]

Ivor,

Agree with Father Ted - many caravan 12 Volt power supplies are poor quality - in that they don't fully rectify and smooth the incoming AC supply - resulting in a 12 Volt DC supply with a considerable AC ripple on top on the CD voltage.

This mixed DC and AC supply (when running on mains) doesn't cause any problems with running lights or charging the battery, but will cause all sorts of issues with radio reception.

The solution is to smooth the 12 volt supply to the radio (and the aerial). An in-line suppressor is easy to fix and may work, but if not:

1. Speak with a electronics specialist and fit a pair of smoothing capacitors, one to the 12 volt output from the power pack, and one just before the radio - these should smooth the AC ripple. This smoothing capacitors are cheap (Maplin is a good source)

2. If smoothing capacitors don't work, then fit a 12 volt to 12 volt regulated power supply - this is a more expensive solution - costing

 

[rob_jax]

Colinn,

Can you hear the noise when on battery, or only when the mains is plugged in? Mains only means a noisy / AC ripple on the caravan power supply - either causing a radio component to fail or oscillate.

Disconnect the speakers - can you still hear the noise? Yes - then it's probably a faulty component in the radio - probably an oscillator in the RF circuits. No - then it's probably a power supply fault - and the above advice on power supply ripple suppression needs to be followed.

Suggestions - try a different radio / CD player, try power line suppression

Robert

 

[Colinn]

Colinn,

Can you hear the noise when on battery, or only when the mains is plugged in? Mains only means a noisy / AC ripple on the caravan power supply - either causing a radio component to fail or oscillate.

Disconnect the speakers - can you still hear the noise? Yes - then it's probably a faulty component in the radio - probably an oscillator in the RF circuits. No - then it's probably a power supply fault - and the above advice on power supply ripple suppression needs to be followed.

Suggestions - try a different radio / CD player, try power line suppression

Robert

thanks, rob. I'll experiment...

 

[rovi]

Thanks, I will look into getting an in line suppressor and smoothing capacitors before I go away again and see how we get on as caravan lives in storage.

Ivor