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Router RFI (interference)

oldskooldaze
Dabbler
Posts: 13
Registered: 03-04-2012

Router RFI (interference)

Got online today for the first time no problems............ Smiley
Anyway i use amateur radio and the router interferes causes white noise with a certain radio frequency 10Mhz
The O2 router was fine , so what happens next as this does not comply  within  the law and is not so good ?
12 REPLIES
Community Veteran
Posts: 5,472
Thanks: 291
Fixes: 4
Registered: 11-08-2007

Re: Router RFI (interference)

Can you use the O2 router instead ?
itsme
Grafter
Posts: 5,924
Thanks: 1
Registered: 07-04-2007

Re: Router RFI (interference)

It's been several years since I designed and submitted devices to test house but I believe the Emissions part of the EMC directive don't cover 30MHz and below.
Community Veteran
Posts: 5,472
Thanks: 291
Fixes: 4
Registered: 11-08-2007

Re: Router RFI (interference)

As far as I remember, EMC testing below 30MHz is only for military applications (MIL-STD-461).
oldskooldaze
Dabbler
Posts: 13
Registered: 03-04-2012

Re: Router RFI (interference)

Quote from: purleigh
As far as I remember, EMC testing below 30MHz is only for military applications (MIL-STD-461).

I can assure you it covers all amateur bands they should be notched in between frequency's  Wink
As for the O2 router i have to send it back !
itsme
Grafter
Posts: 5,924
Thanks: 1
Registered: 07-04-2007

Re: Router RFI (interference)

Are you aware how they test for radiated emissions and the Open Site test setup? I can't remember testing below 30MHz
knowdice
Grafter
Posts: 328
Registered: 25-04-2008

Re: Router RFI (interference)

Do you have any idea where the interference is coming from?
PSU?
Mains Cable?
ADSL Cable?
LAN Cable?
Problem is that router should meet certain specifications on its own, but may fail to meet these once it's installed due to how it's installed and which cables are used.
And the cables supplied with the unit may not be exactly the same type and specification of cable that it was tested with...
mattturner
Grafter
Posts: 246
Thanks: 2
Registered: 25-06-2009

Re: Router RFI (interference)

Quote from: oldskooldaze
Anyway i use amateur radio and the router interferes causes white noise with a certain radio frequency 10Mhz

Hi,
From experience I suspect that this is caused by the switch mode power supply we use, do you have any way of testing this? It would be hard to pin it down to the PSU as the switching frequency would change depending on the load (so powering down the router would cause the PSU switching frequency to drop).
Matt
oldskooldaze
Dabbler
Posts: 13
Registered: 03-04-2012

Re: Router RFI (interference)

Quote from: Matt
Quote from: oldskooldaze
Anyway i use amateur radio and the router interferes causes white noise with a certain radio frequency 10Mhz

Hi,
From experience I suspect that this is caused by the switch mode power supply we use, do you have any way of testing this? It would be hard to pin it down to the PSU as the switching frequency would change depending on the load (so powering down the router would cause the PSU switching frequency to drop).
Matt

Its definitely the power supply , i have tried ferrite rings ballun etc but to no avail , any ideas as its causing me grief ?
You were right about  powering down the router would cause the PSU switching frequency to drop.  Wink
knowdice
Grafter
Posts: 328
Registered: 25-04-2008

Re: Router RFI (interference)

If it's a "wall wart" style may be change for one which has a mains lead, then you can put additional ferrite rings on both input and output.
Also, the actual rings seem to work better than the split cores, especially if you can get a couple of turns on them.
oldskooldaze
Dabbler
Posts: 13
Registered: 03-04-2012

Re: Router RFI (interference)

Quote from: knowdice
If it's a "wall wart" style may be change for one which has a mains lead, then you can put additional ferrite rings on both input and output.
Also, the actual rings seem to work better than the split cores, especially if you can get a couple of turns on them.

All good advice but i don't see why i should pay for another supply   Huh
knowdice
Grafter
Posts: 328
Registered: 25-04-2008

Re: Router RFI (interference)

Agreed...
But sometimes it's easiest to go for the pragmatic solution and just fix things... Embarrassed
mattturner
Grafter
Posts: 246
Thanks: 2
Registered: 25-06-2009

Re: Router RFI (interference)

Hi oldskooldaze,
I'm afraid we don't have any alternative PSUs available that you could use. I've gone back to our supplier and they've not seen this before, nor do they have alternative PSUs available.
We'll look into this a little more next week when their technical expert is back in the office.
Thanks,
Matt