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

[David, G3YYD]

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.

73 David G3YYD

David G4ASR Wrote

The 100W totally obliterated my broadband access. Son not impressed!
Presumably you just wind the telephone lead (before the router) around a suitable ferrite core.
Or is there a better way?

73 David G4ASR - VHF Manager!