[UK-CONTEST] re ADSL Modem RFI

[Ian Maude]

2009/11/17 David, G3YYD <g3yyd at btinternet.com>

> 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.
>

Several actually, and a clamp.  They are fixed under the floor of the shack
where I ran the lead-in.  Mine is dropwire 10 which is circular and has 4
wires plus 2 steel support wires.


>
> 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.
>

Oh I am not worried about that, they trained me after all :)

>
> 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.
>

For me, the Netgear is useless.  I really do not know why.  The DLink is
absolutely solid.  I got Linda to run 200W on her 80m net yesterday morning
and set off a ping session to bbc.co.uk without a single dropped ping in
over 2000 pings.  It works for me, YMMV :)

73 Ian

-- 
Ian J Maude, G0VGS
SysOp GB7MBC & HB9DRV-9 DX Clusters
Member RSGB, GQRP 9838, FISTS 14077 | K3 #455
http://www.amateurradiotraining.org