[Gllug] ADSL problem

[Chris Bell]

On Mon 28 Feb, Nix wrote:
> 

> 
> Surely this is only true if you can rewire the phone cabling in your
> house at the same time as you install ADSL, or if you're lucky enough
> to have your master socket close to where you want to put your ADSL device
> so you can run an extension cable?
> 
> In my case, with a pre-wired house, an ADSL router in the furthest phone
> socket from the master socket, and a somewhat battered master soket
> which doesn't work as a phone socket at all (!?), there seemed to be
> little point in going for the theoretical benefits of a master-socket-
> installed microfilter when the practical consequences would be so tricky
> to resolve.
> 
   The old system used to have either a master phone or a master external
sounder to terminate the incoming pair and tap off the ringer circuit. All
sounders were low impedance devices, designed to be connected with up to 6
in series, and secondary phones were connected using 2 pairs, one pair for
the phones in parallel and the other pair for the series connected sounders.
The ringer circuit was routed through an additional pair of contacts on each
secondary phone to prevent bell tinkle during dialling. There was usually
just a connection box that terminated the incoming cable and linked it
directly to the master phone.
   The replacement system uses parallel phones and up to 4 "high impedance"
(about 1K ohms) sounders connected in parallel across the bell circuit
provided by a capacitor at the master box. Some locations were pre-wired,
and fitted with master boxes that meet the BT electrical spec, but were not
supplied by BT and can have different external designs. They will obviously
not accept the BT style front panels.
   The BT style master box and replacement front panel, together with an
ADSL modem located close by, may be noticeably better if you are in a
marginal location or have extensive cabling for local phone extensions. Once
converted, the higher level ethernet signals are much easier to link on to
the rest of your network, although an extra cable may be required.
   In my case, I have dropped a Cat5 cable under the ground floor from the
master box near the front door to the rest of the system, where it pops out
between the floorboards.

-- 
Chris Bell

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