The Mystery of the Phantom Whistling Kettle - an Unusual Case of RFI!

One night during recent testing of the revised earthing arrangement of my HF Windom antenna I became aware that I had signs of RF feedback on 7Mhz SSB when running QRO especially with the audio processing switched on in my FT1000MP – a sure sign that all is not well with the earth routing in my newly relocated shack downstairs in the conservatory . I had also heard a few occasional thuds from the loudspeakers of the hi-fi system.

I then became aware that I could hear the electric kettle whistling in the kitchen which has a rather unusual mournful sound as the whistling dies away after the appliance switches off after reaching boiling point. This puzzled me because that apart from myself, I thought that the house was empty.

So I went into the kitchen to investigate thinking perhaps I had an un-announced visitor but the kitchen was empty and what is more,the water in the kettle was cold so it could not have boiled to create the whistle! It was only at this point that I realised that the whistle on this new Morphy-Richards kettle was not in fact driven by steam but was electronic in origin and had a switch underneath to turn the noise on or off! A couple of bursts of QRO on 7Mhz again produced the same mournful wailing again confirming that I had clearly got quite a bit of stray RF getting into the house wiring since the kettle 13A plug in the kitchen was at least 35ft away from the earthing point of the HF rig and Expert 1K-FA linear amp.

Helped by Peter G4FYY, some general re-routing and shortening of the various earth leads ensued and separation of the earth route from the ground point of the in-line choke balun in the feeder to the Windom antenna to the copper ground stake. This seems to have cured the earth problem and now when I hear the kettle whistle I know that a cup of tea is really on its way !

73, de Derek G3GRO