[UK-CONTEST] David G4ASR Broadband Box - Maximising RF immunity

[David Ferrington, M0XDF]

Take a look at https://www.merchantamerica.com/kyfilters

fantastic on ADSL - stopped all my RFI into the ADSL

--  
73 de M0XDF

On 23 Mar 2009, at 11:54, David, G3YYD wrote:

> David
>
> You cannot be the only one. So this note will be helpful to others.  
> This
> applies to people using BT and probably Kingston (Hull area) as well  
> for
> the supply of the line.
>
> First I have tried a few different routers for immunity to RF. The  
> best
> I have found is Netgear DG834G.
>
> Second if there is any non-linearity in the phone system then it will
> demodulate the RF envelope along with its harmonics, which will impact
> on the 26KHz to circa 1MHz bandwidth of the ADSL modulation. So if you
> have a crackly phone line get it fixed. You have to be persistent for
> them to accept it.
>
> Third connect your router direct to the master socket box  that is  
> where
> the incoming phone line terminates. Even if you have to reroute the  
> line
> to do so. Use a replacement ADSL filter face plate on the master  
> socket
> - BT sell them among others. This removes any elements of non- 
> linearity
> that have been created by the phones and the extension wiring. It will
> also improve your broadband signal to noise ratio and hence give you a
> higher speed unless you are very close to the exchange ADSL equipment.
>
> Fourth, The standard RSGB ferrite ring will fit into most master  
> socket
> boxes. You need a wire pair but do not use enamel wire (breakdown
> voltage too low) use small plastic covered wire and wrap 14 turns  
> around
> the ring and connect between the outside phone line and the connection
> on the master socket. (If you have breakthrough on your phones put a
> ferrite ring in their connection boxes as well)
>
> Having done the above at full power I have no problem with broadband
> router going down from 160m to 2m for SSB/CW/RTTY/Digital etc. My 80m
> antenna is not far above my overhead phone line so I hate to think how
> much RF there is on that phone line.
>
> Oh do not use the BT boxes they were the worst of the routers, I test
> for RF immunity as well as being the slowest.
>