RF interference from fridge.

[Leighb]

I have identified the cause of severe RF interference on my H/H VHF radio as being the fridge.

This uses a Danfoss compressor powered by either 12V or 240V, the interference is caused whether mains or 12V is powering the unit.

Any suggestions on how I can suppress this?

 

[Mrnotming]

Maybe put ferrites on the supply cables?
Or call Danfoss as there may be a motor or controller fault?

 

[MM5AHO]

Did it always have this RF interfereing output?
If not something changed? That might be a clue to the issue.
If its 240/12V, it could be that it runs always on 12V, but 240V if supplied is transformed to 12V. (as opposed to other way about).
In such a transformer, its likely that its a switch mode system. These are notoriously noisy (RF wise) but there might be solutions. An RF filter could be fitted to the output. One could be made, involving capacitors and perhaps inductors to remove any residual AC from the 12V supply to the motor etc.
Its also possible that the motor in the compressor is the source. Does it always have the same noise? Listen to the noise on an AM radio, while the compressor cuts in and out. Changed noise? Mostly when motor runs? Maybe motor is source. If noise always there irrespective of load, then maybe power supply system.

 

[Lon nan Gruagach]

Perhaps your motor noise suppression capacitor is goosed. This may also be causing excessive wear to the motor brushes and commutator.

 

[BobnLesley]

...Any suggestions on how I can suppress this?...

Sorry no, but just to say that it'll stop any Navtex broadcasts 'auto-saving' too - they still run unbroken across the screen though? - so if there's one you really can't afford to miss, turn off the fridge a few minutes/hours before it's due.

 

[homer]

After plenty of duff "solutions" (ferrites, capacitors etc.), I found that the ultimate solution was to run new cables (twisted pair) to the VHF directly from the batteries (rather than from the common power suply to the switchboard).

 

[MoodySabre]

After plenty of duff "solutions" (ferrites, capacitors etc.), I found that the ultimate solution was to run new cables (twisted pair) to the VHF directly from the batteries (rather than from the common power suply to the switchboard).

It's on his handheld

 

[Billjratt]

My HF set was bedevilled by noise from the fridge -a Waeco setup using a Danfoss compressor. The noise wasn't motor though, it was a chirp chirp indicating control communication between the various components. I was never aware of a problem with any of the VHF sets -fixed or hand-held.
I'd have a check of the power cabling to the compressor -especially the ground. Can you move the HH round the boat to be sure its from the compressor and not the controller/ thermostat?
Screening of the offending component may help, but I feel it would be papering over a crack.
Out of interest, does your VHF 'hear' the tick of the echosounder as well?

 

[MM5AHO]

It can be amazing what things emit RF and have potential to cause interference with wanted signals.
I can "hear" the chirp of my GPS sending data down its line from the antenna on various HF frequencies. On lower frequencies (2-6 MHz) its a strong signal blocking wanted ones.

But I don't have a fridge to add to that!