>ipal.net> wrote in message
>news:fqma4m1ier@news3.newsguy.com
>
>[snip]
>
>: : I've seen cables, including CAT5, with both twisting
>: : _and_ shielding around the whole cable assembly. I
>: : don't know how much the effectiveness works together.
>: : I have not had a case where I would consider using it.
>
>That's STP (shielded twisted pair) and is not really worth it for most
>applications. There is a military spec. for it somewhere, I believe.
>
>It's also a different impedance to UTP so may not work correctly with all
>equipment.

> What do you
> mean when you say "flex". I suspect you'll be amused to learn that in the
> USA that word is electricians short hand for flexible metallic conduit. I
> doubt that United Kingdom "flex" is anything like Flexible Metallic
> Conduit a photograph of which can be found at
> <http://www.tradexpro.com/product_catalogs/machinery_electronics/cable_wire/in-co...-->.

> There is obviously a significant difference in the phone systems in the
> two
> countries. Our phones have the bells in parallel and if thee are too many
> the wrong impedance is presented to the exchange, and no ringing voltage
> will get sent. I have never seen a UK approved phone with a REN less than
> 1, but there were plenty of 2s & 3s about at one time.
>
> You can buy a REN booster ( a mains powered device) which allows many more
> phones.

>

>
> For the North Americans)
> What is unusual with the UK system apart from our "special" plug
> and receptacle instead of an RJ11, is the fact that we use a
> third wire which couples all the ringers in parallel to a
> capacitor in the master socket to which the incommer is connected.
> Many modern phones do not even use this "bell wire" and just use
> the A and B wires (tip & ring).

> ipal.net> wrote:
>
> [snip]
>

>> I've seen cables, including CAT5, with both twisting _and_
>> shielding around the whole cable assembly. I don't know how
>> much the effectiveness works together. I have not had a case
>> where I would consider using it.

>
> That's STP (shielded twisted pair) and is not really worth it for
> most applications. There is a military spec. for it somewhere, I
> believe.
>
> It's also a different impedance to UTP so may not work correctly
> with all equipment.

>In North America again (I don't know about elsewhere) the normal
>phone uses 3 wires to connect to the two wires of the phone
>circuit. The yellow wire carries the ring signal. Just disconnect
>that and the phone won't ring, and the load is zero.

> Foxtrot wrote:

>>

> ... snip ...

>>
>> Is there is a greaterlikelihood of hum if I connect a "2 wire"
>> phone extension by using one wire from a twisted pair and taking
>> the second wire from a different twisted pair?

>
> Yes. The idea of twisted pairs is that an interference appears on
> both lines, and thus tends to cancel itself. Separating the lines
> makes it easy for unequal induction.

>"CBFalconer" yahoo.com> wrote in message
>news:47CF3D42.810AA5C9@yahoo.com
>: : Ivor Jones wrote:
>
>[snip]
>
>: : I replaced your non-standard (: :) quote markers with
>: : the normal '>'. Please don't use thos non-standard
>: : characters. They foul up other software.
>
>With respect, and without wishing to start a row, that's *your* problem. I
>use non-standard quote marks for a purpose. If your system can't cope with
>that, then it's up to *you* to do something about it. I have been using
>the quote marks I use for several years and you are the first to complain.

>In article <47CDEAD6.2D67BCF3@yahoo.com>, cbfalconer@yahoo.com
>says...

>> Foxtrot wrote:

>>>

>> ... snip ...

>>>
>>> Is there is a greaterlikelihood of hum if I connect a "2 wire"
>>> phone extension by using one wire from a twisted pair and taking
>>> the second wire from a different twisted pair?

>>
>> Yes. The idea of twisted pairs is that an interference appears on
>> both lines, and thus tends to cancel itself. Separating the lines
>> makes it easy for unequal induction.

>
>Twisting also makes the loop area low (average over a long stretch
>is nil). Separating them makes a large loop, increasing the size of
>the antenna.