The British DX Club

Shortwave interference from Power Line Modems / Adaptors

There is a new and deadly threat to our hobby of Shortwave DXing and Listening and it comes in the form of a little device designed to distibute broadband and television signals through the mains wiring. Severe interference across the shortwave band from 3-30 MHz is the effect of these units known as "Power Line Modems" or "Power Line Adaptors".

One model in particular currently being supplied to BT Vision customers in the UK seems to be causing the most concern. The models in question are usually made by Comtrend - model DH-10PF. The interference, in the form of a high pitched digital noise, has been noted from such devices 24 hours a day over a wide area, often exceeding 100m.

UK QRM videos

See a demonstration of the interference on Youtube

Demonstration of BT Vision interference

Second video with update

Third video - Know Your Enemy Demonstration of interference from the Comtrend adaptor and how to track down interference.

Reporting the interference to Ofcom

You can report the interference direct to Ofcom either by phoning 0300 123 3333 or by filling in the online form Ofcom Interference Investigation Form

Don't worry about the £50 charge as this will not apply if the source of the interference is outside your property. After you report a complaint, Ofcom will send an engineer to investigate the source of the interference. This will be treated confidentially by Ofcom and if it turns out to be BT Vision adaptor in a neighbouring property, they will ask BT to solve the problem. In most cases BT will be able to replace the Comtrend adaptors with a hard wired or wi-fi link to remove the interference.

New Save Shortwave Petition

The first Save Shortwave petition on the Prime Minister's web site closed on 11 February 2009 having received 3554 signatures. The Government's reply can be read here.

In its reply to the first petition, the Government said that PLT must comply with the 2006 EMC regulations. This new e-petition calls on the authorities to test and remove from the market all PLT devices which fail to comply. Please sign this petition and encourage others to do so. The deadline is 24 October 2009. Sign the new Petition!

UKQRM news group

If you are suffering from this interference from a neighbour or are concerned about the issue, we also recommend you join UKQRM. The group is campaigning to get these devices withdrawn and also offers advice on how you can get Ofcom and BT to resolve a specific interference complaint. UKQRM Yahoo group

For further information see the UK QRM web site