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published2004
Beginner
439 Views
Message 1 of 5

ADSL2+ RFI

I am one of 50 thousand radio amateurs in the UK ... I was licensed 40 years ago by the Home office to operater a transmitting station ... One of the bands I am allowed to transmit on is what we call Top band .. it covers  1.8 to 2 MHz

 

Not long ago BT started using ADSL2+ in this area to overhead lines .... unfortunately ADSL2+ goes up to 2.2 MHz so whenever I transmit even on very very low power it takes out my Broadband connection completely and probably my neighbors as well.

 

I never had a problem with ADSL which only goes up to about 1.1MHz and I gather that ADSL2+ does not cause so much of a problem if the BT lines are underground as they have been on new properties since 1982 but to Roll it out on overhead lines is asking for trouble because there does not seem to be effective notching for Top band .... I wonder if there is Notching on some of the other Amateur bands like 500K Hz or 136 KHz

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4 REPLIES 4
Distinguished Sage
Distinguished Sage
429 Views
Message 2 of 5

Re: ADSL2+ RFI

I gave up on topband years ago, not active at all now on any band, as any sort of transmission plays havoc with the broadband, TV and everything else.

 

Reception is the same, just continual QRM from everything.

 

The only solution for keen amateurs, is to move out into the country, away from everybody.

 

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G3NDI
Aspiring Expert
422 Views
Message 3 of 5

Re: ADSL2+ RFI

The problems of EMC with ADSL have been raised a number of times in the amateur journal, RadCom, over the recent past.   This includes the short-wave interference from the Power Line Ethernet Adapter plugs that are sometimes suggested on the Forum.

published2004 will find in the article by Dr Lauder some comments on ADSL being susceptible to 1.8 and 3.5 MHz transmissions, e.g Oct 2005 and efforst to reduce this susceptibilty.  Investigations were even carried out by BT which included fitting of the new front plate to the master socket.  It was also found necessary to insert a common mode filter between the ADSL router and the microfilter.   He suggests the overhead line should be well balanced at RF compared to the internal house wiring.  Other comments are made, but this forum is not really the place for detailed technical discussion.    If  you are an RSGB member publisher2004 then you will have access to Dr Lauder's' EMC column on the web site.

 

Rodney Fry

G3NDI

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Distinguished Sage
Distinguished Sage
418 Views
Message 4 of 5

Re: ADSL2+ RFI

We will have to leave it like that, as this thread is "off topic" for this forum.

 

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published2004
Beginner
410 Views
Message 5 of 5

Re: ADSL2+ RFI

It is off topic for all the forums because nobody wants address the issue

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