[UK-CONTEST] re ADSL Modem RFI

[David, G3YYD]

Ian

Did you try a ferrite ring (one of those the RSGB sells works well) on 
the drop wire pair running into the BT master socket. In my case it fits 
inside the master socket. You need a minimum of 14 turns. This will then 
force the RF on the line at HF to be equal on both legs of the drop 
wire. When the RF reaches the balanced input of the router it will 
maximise the cancellation of the RX signal. By the way do not wind the 
toroid with enamelled copper wire it does not have a high enough voltage 
rating. I used internal phone cable with the outer sheath stripped off.

I do not have any added  filtering on the power lead supplying the router.

In theory you should not alter anything between the master socket and 
BTs line but they are not going to throw away your custom (£notes) so in 
practice that regulation is not enforceable in this context.

I use a DG834G  with the drop wire ferrite in place plus a ADSL 
faceplate in the master socket to isolate the extension wiring from the 
router. I run full power on all bands 160-10 plus 2m without any 
degradation in the broadband signal to noise. One leg of my 80m dipole 
and my 160m vertical top loading wire run above and to once side of the 
BT drop wire. The BT supplied modem router was very poor on RF immunity 
compared to the Netgear.

David G3YYD

Ian Maude wrote:
> This has been an interesting thread for me for several reasons.  Firstly,
> *both* my routers (main and spare) expired with different faults at the same
> time and it had to be a Sunday!  I nipped out and bought a Netgear router.
>  I should have known better due to past difficulties but I needed to keep
> the cluster running :)
> The Netgear hates 80m.  This newer model was better and could stand 50W
> without dropping the connection.  Anything toward 100W and a reasonable over
> and the connection would drop due to queue length.
> I bought a DLink G624T online and connected that up.  This is the same as
> the router that died and has no such problems.  I can run 400W without
> losing a single ping!
> I was a BT engineer for most of my working life and the dropwire crosses the
> trap dipole but at right angles and well away from the current maximum.  The
> line then comes straight into the shack and on to a filtered NTE.  I have
> done many tests, moving the router and reconnecting wiring etc.  The DLink
> works every time without issues.
> Now I know of other people who have the opposite experience and I have yet
> to discover why.  I cannot imagine why one router would be so much better
> than another in this regard.  I used the same line cord with both routers
> using 2 ferrite cores at each end of the cord with about 8 turns on each
> one.
>
> 73 Ian
>
>